coreos-cloudinit: bump to 0.10.4

Merge pull request #240 from epankala/euca4_compat_fix
AWS: Eucalyptus 4.x compatibility fix
2014-09-24 19:25:34 -07:00 · 2014-09-24 10:55:39 -07:00 · 2014-09-24 20:33:29 +03:00 · 2014-09-24 07:42:09 -07:00 · 2014-09-23 17:59:32 -07:00 · 2014-09-23 17:59:19 -07:00
143 changed files with 10552 additions and 1801 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 *.swp
 bin/
-pkg/
+coverage/
+gopath/
--- a/.travis.yml
+++ b/.travis.yml
@@ -0,0 +1,10 @@
+language: go
+go:
+  - 1.3
+  - 1.2
+
+install:
+ - go get code.google.com/p/go.tools/cmd/cover
+
+script:
+ - ./test
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -39,22 +39,25 @@ Thanks for your contributions!

 ### Format of the Commit Message

-We follow a rough convention for commit messages borrowed from AngularJS. This
-is an example of a commit:
+We follow a rough convention for commit messages that is designed to answer two
+questions: what changed and why. The subject line should feature the what and
+the body of the commit should describe the why.

 ```
-    feat(scripts/test-cluster): add a cluster test command
+environment: write new keys in consistent order

-    this uses tmux to setup a test cluster that you can easily kill and
-    start for debugging.
+Go 1.3 randomizes the ordering of keys when iterating over a map.
+Sort the keys to make this ordering consistent.
+
+Fixes #38
 ```

 The format can be described more formally as follows:

 ```
-<type>(<scope>): <subject>
+<subsystem>: <what changed>
 <BLANK LINE>
-<body>
+<why this change was made>
 <BLANK LINE>
 <footer>
 ```
@@ -63,25 +66,3 @@ The first line is the subject and should be no longer than 70 characters, the
 second line is always blank, and other lines should be wrapped at 80 characters.
 This allows the message to be easier to read on GitHub as well as in various
 git tools.
-
-#### Subject Line
-
-The subject line contains a succinct description of the change.
-
-#### Allowed `<type>`s
- *feat* (feature)
- *fix* (bug fix)
- *docs* (documentation)
- *style* (formatting, missing semi colons, …)
- *refactor*
- *test* (when adding missing tests)
- *chore* (maintain)
-
-#### Allowed `<scope>`s
-
-Scopes can anything specifying the place of the commit change in the code base - 
-for example, "api", "store", etc.
-
-
-For more details on the commit format, see the [AngularJS commit style
-guide](https://docs.google.com/a/coreos.com/document/d/1QrDFcIiPjSLDn3EL15IJygNPiHORgU1_OOAqWjiDU5Y/edit#).
--- a/Documentation/cloud-config-oem.md
+++ b/Documentation/cloud-config-oem.md
@@ -0,0 +1,37 @@
+## OEM configuration
+
+The `coreos.oem.*` parameters follow the [os-release spec][os-release], but have been repurposed as a way for coreos-cloudinit to know about the OEM partition on this machine. Customizing this section is only needed when generating a new OEM of CoreOS from the SDK. The fields include:
+
+- **id**: Lowercase string identifying the OEM
+- **name**: Human-friendly string representing the OEM
+- **version-id**: Lowercase string identifying the version of the OEM
+- **home-url**: Link to the homepage of the provider or OEM
+- **bug-report-url**: Link to a place to file bug reports about this OEM
+
+coreos-cloudinit renders these fields to `/etc/oem-release`.
+If no **id** field is provided, coreos-cloudinit will ignore this section.
+
+For example, the following cloud-config document...
+
+```yaml
+#cloud-config
+coreos:
+  oem:
+    id: rackspace
+    name: Rackspace Cloud Servers
+    version-id: 168.0.0
+    home-url: https://www.rackspace.com/cloud/servers/
+    bug-report-url: https://github.com/coreos/coreos-overlay
+```
+
+...would be rendered to the following `/etc/oem-release`:
+
+```yaml
+ID=rackspace
+NAME="Rackspace Cloud Servers"
+VERSION_ID=168.0.0
+HOME_URL="https://www.rackspace.com/cloud/servers/"
+BUG_REPORT_URL="https://github.com/coreos/coreos-overlay"
+```
+
+[os-release]: http://www.freedesktop.org/software/systemd/man/os-release.html
--- a/Documentation/cloud-config.md
+++ b/Documentation/cloud-config.md
@@ -1,10 +1,10 @@
 # Using Cloud-Config

-CoreOS allows you to declaratively customize various OS-level items, such as network configuration, user accounts, and systemd units. This document describes the full list of items we can configure. The `coreos-cloudinit` program uses these files as it configures the OS after startup or during runtime. 
+CoreOS allows you to declaratively customize various OS-level items, such as network configuration, user accounts, and systemd units. This document describes the full list of items we can configure. The `coreos-cloudinit` program uses these files as it configures the OS after startup or during runtime. Your cloud-config is processed during each boot.

 ## Configuration File

-The file used by this system initialization program is called a "cloud-config" file. It is inspired by the [cloud-init][cloud-init] project's [cloud-config][cloud-config] file. which is "the defacto multi-distribution package that handles early initialization of a cloud instance" ([cloud-init docs][cloud-init-docs]). Because the cloud-init project includes tools which aren't used by CoreOS, only the relevant subset of its configuration items will be implemented in our cloud-config file. In addition to those, we added a few CoreOS-specific items, such as etcd configuration, OEM definition, and systemd units.
+The file used by this system initialization program is called a "cloud-config" file. It is inspired by the [cloud-init][cloud-init] project's [cloud-config][cloud-config] file, which is "the defacto multi-distribution package that handles early initialization of a cloud instance" ([cloud-init docs][cloud-init-docs]). Because the cloud-init project includes tools which aren't used by CoreOS, only the relevant subset of its configuration items will be implemented in our cloud-config file. In addition to those, we added a few CoreOS-specific items, such as etcd configuration, OEM definition, and systemd units.

 We've designed our implementation to allow the same cloud-config file to work across all of our supported platforms.

@@ -16,7 +16,7 @@ We've designed our implementation to allow the same cloud-config file to work ac

 The cloud-config file uses the [YAML][yaml] file format, which uses whitespace and new-lines to delimit lists, associative arrays, and values.

-A cloud-config file should contain an associative array which has zero or more of the following keys:
+A cloud-config file should contain `#cloud-config`, followed by an associative array which has zero or more of the following keys:

 - `coreos`
 - `ssh_authorized_keys`
@@ -40,9 +40,9 @@ CoreOS tries to conform to each platform's native method to provide user data. E
 #### etcd

 The `coreos.etcd.*` parameters will be translated to a partial systemd unit acting as an etcd configuration file.
-We can use the templating feature of coreos-cloudinit to automate etcd configuration with the `$private_ipv4` and `$public_ipv4` fields. For example, the following cloud-config document...
+If the platform environment supports the templating feature of coreos-cloudinit it is possible to automate etcd configuration with the `$private_ipv4` and `$public_ipv4` fields. For example, the following cloud-config document...

-```
+```yaml
 #cloud-config

 coreos:
@@ -57,7 +57,7 @@ coreos:

 ...will generate a systemd unit drop-in like this:

-```
+```yaml
 [Service]
 Environment="ETCD_NAME=node001"
 Environment="ETCD_DISCOVERY=https://discovery.etcd.io/<token>"
@@ -68,72 +68,73 @@ Environment="ETCD_PEER_ADDR=192.0.2.13:7001"
 For more information about the available configuration parameters, see the [etcd documentation][etcd-config].
 Note that hyphens in the coreos.etcd.* keys are mapped to underscores.

+_Note: The `$private_ipv4` and `$public_ipv4` substitution variables referenced in other documents are only supported on Amazon EC2, Google Compute Engine, OpenStack, Rackspace, DigitalOcean, and Vagrant._
+
 [etcd-config]: https://github.com/coreos/etcd/blob/master/Documentation/configuration.md

+#### fleet
+
+The `coreos.fleet.*` parameters work very similarly to `coreos.etcd.*`, and allow for the configuration of fleet through environment variables. For example, the following cloud-config document...
+
+```yaml
+#cloud-config
+
+coreos:
+    fleet:
+        public-ip: $public_ipv4
+        metadata: region=us-west
+```
+
+...will generate a systemd unit drop-in like this:
+
+```yaml
+[Service]
+Environment="FLEET_PUBLIC_IP=203.0.113.29"
+Environment="FLEET_METADATA=region=us-west"
+```
+
+For more information on fleet configuration, see the [fleet documentation][fleet-config].
+
+[fleet-config]: https://github.com/coreos/fleet/blob/master/Documentation/deployment-and-configuration.md#configuration
+
 #### update

 The `coreos.update.*` parameters manipulate settings related to how CoreOS instances are updated.

+These fields will be written out to and replace `/etc/coreos/update.conf`. If only one of the parameters is given it will only overwrite the given field. 
+The `reboot-strategy` parameter also affects the behaviour of [locksmith](https://github.com/coreos/locksmith). 
+
 - **reboot-strategy**: One of "reboot", "etcd-lock", "best-effort" or "off" for controlling when reboots are issued after an update is performed.
  - _reboot_: Reboot immediately after an update is applied.
  - _etcd-lock_: Reboot after first taking a distributed lock in etcd, this guarantees that only one host will reboot concurrently and that the cluster will remain available during the update.
  - _best-effort_ - If etcd is running, "etcd-lock", otherwise simply "reboot".
  - _off_ - Disable rebooting after updates are applied (not recommended).
+- **server**: is the omaha endpoint URL which will be queried for updates.
+- **group**:  signifies the channel which should be used for automatic updates.  This value defaults to the version of the image initially downloaded. (one of "master", "alpha", "beta", "stable")

-```
+*Note: cloudinit will only manipulate the locksmith unit file in the systemd runtime directory (`/run/systemd/system/locksmithd.service`). If any manual modifications are made to an overriding unit configuration file (e.g. `/etc/systemd/system/locksmithd.service`), cloudinit will no longer be able to control the locksmith service unit.*
+
+##### Example
+
+```yaml
 #cloud-config
 coreos:
  update:
    reboot-strategy: etcd-lock
 ```

-#### oem
-
-The `coreos.oem.*` parameters follow the [os-release spec][os-release], but have been repurposed as a way for coreos-cloudinit to know about the OEM partition on this machine:
-
- **id**: Lowercase string identifying the OEM
- **name**: Human-friendly string representing the OEM
- **version-id**: Lowercase string identifying the version of the OEM
- **home-url**: Link to the homepage of the provider or OEM
- **bug-report-url**: Link to a place to file bug reports about this OEM
-
-coreos-cloudinit renders these fields to `/etc/oem-release`.
-If no **id** field is provided, coreos-cloudinit will ignore this section.
-
-For example, the following cloud-config document...
-
-```
-#cloud-config
-coreos:
-  oem:
-    id: rackspace
-    name: Rackspace Cloud Servers
-    version-id: 168.0.0
-    home-url: https://www.rackspace.com/cloud/servers/
-    bug-report-url: https://github.com/coreos/coreos-overlay
-```
-
-...would be rendered to the following `/etc/oem-release`:
-
-```
-ID=rackspace
-NAME="Rackspace Cloud Servers"
-VERSION_ID=168.0.0
-HOME_URL="https://www.rackspace.com/cloud/servers/"
-BUG_REPORT_URL="https://github.com/coreos/coreos-overlay"
-```
-
-[os-release]: http://www.freedesktop.org/software/systemd/man/os-release.html
-
 #### units

-The `coreos.units.*` parameters define a list of arbitrary systemd units to start. Each item is an object with the following fields:
+The `coreos.units.*` parameters define a list of arbitrary systemd units to start after booting. This feature is intended to help you start essential services required to mount storage and configure networking in order to join the CoreOS cluster. It is not intended to be a Chef/Puppet replacement.
+
+Each item is an object with the following fields:

 - **name**: String representing unit's name. Required.
- **runtime**: Boolean indicating whether or not to persist the unit across reboots. This is analagous to the `--runtime` argument to `systemd enable`. Default value is false.
- **enable**: Boolean indicating whether or not to handle the [Install] section of the unit file. This is similar to running `systemctl enable <name>`. Default value is false.
+- **runtime**: Boolean indicating whether or not to persist the unit across reboots. This is analogous to the `--runtime` argument to `systemctl enable`. The default value is false.
+- **enable**: Boolean indicating whether or not to handle the [Install] section of the unit file. This is similar to running `systemctl enable <name>`. The default value is false.
 - **content**: Plaintext string representing entire unit file. If no value is provided, the unit is assumed to exist already.
- **command**: Command to execute on unit: start, stop, reload, restart, try-restart, reload-or-restart, reload-or-try-restart. Default value is restart.
+- **command**: Command to execute on unit: start, stop, reload, restart, try-restart, reload-or-restart, reload-or-try-restart. The default behavior is to not execute any commands.
+- **mask**: Whether to mask the unit file by symlinking it to `/dev/null` (analogous to `systemctl mask <name>`). Note that unlike `systemctl mask`, **this will destructively remove any existing unit file** located at `/etc/systemd/system/<unit>`, to ensure that the mask succeeds. The default value is false.

 **NOTE:** The command field is ignored for all network, netdev, and link units. The systemd-networkd.service unit will be restarted in their place.

@@ -141,7 +142,7 @@ The `coreos.units.*` parameters define a list of arbitrary systemd units to star

 Write a unit to disk, automatically starting it.

-```
+```yaml
 #cloud-config

 coreos:
@@ -158,15 +159,12 @@ coreos:
          Restart=always
          ExecStart=/usr/bin/docker start -a redis_server
          ExecStop=/usr/bin/docker stop -t 2 redis_server
-          
-          [Install]
-          WantedBy=local.target
 ```

-Start the builtin `etcd` and `fleet` services:
+Start the built-in `etcd` and `fleet` services:

-```
-# cloud-config
+```yaml
+#cloud-config

 coreos:
    units:
@@ -183,7 +181,7 @@ The `ssh_authorized_keys` parameter adds public SSH keys which will be authorize
 The keys will be named "coreos-cloudinit" by default.
 Override this by using the `--ssh-key-name` flag when calling `coreos-cloudinit`.

-```
+```yaml
 #cloud-config

 ssh_authorized_keys:
@@ -195,7 +193,7 @@ ssh_authorized_keys:
 The `hostname` parameter defines the system's hostname.
 This is the local part of a fully-qualified domain name (i.e. `foo` in `foo.example.com`).

-```
+```yaml
 #cloud-config

 hostname: coreos1
@@ -209,7 +207,7 @@ All but the `passwd` and `ssh-authorized-keys` fields will be ignored if the use
 - **name**: Required. Login name of user
 - **gecos**: GECOS comment of user
 - **passwd**: Hash of the password to use for this user
- **homedir**: User's home directory. Defaults to /home/<name>
+- **homedir**: User's home directory. Defaults to /home/\<name\>
 - **no-create-home**: Boolean. Skip home directory creation.
 - **primary-group**: Default group for the user. Defaults to a new group created named after the user.
 - **groups**: Add user to these additional groups
@@ -228,7 +226,7 @@ The following fields are not yet implemented:
 - **selinux-user**: Corresponding SELinux user
 - **ssh-import-id**: Import SSH keys by ID from Launchpad.

-```
+```yaml
 #cloud-config

 users:
@@ -267,7 +265,7 @@ Using a higher number of rounds will help create more secure passwords, but give

 Using the `coreos-ssh-import-github` field, we can import public SSH keys from a GitHub user to use as authorized keys to a server.

-```
+```yaml
 #cloud-config

 users:
@@ -280,17 +278,17 @@ users:
 We can also pull public SSH keys from any HTTP endpoint which matches [GitHub's API response format](https://developer.github.com/v3/users/keys/#list-public-keys-for-a-user).
 For example, if you have an installation of GitHub Enterprise, you can provide a complete URL with an authentication token:

-```
+```yaml
 #cloud-config

 users:
  - name: elroy
-    coreos-ssh-import-url: https://token:<OAUTH-TOKEN>@github-enterprise.example.com/users/elroy/keys
+    coreos-ssh-import-url: https://github-enterprise.example.com/api/v3/users/elroy/keys?access_token=<TOKEN>
 ```

 You can also specify any URL whose response matches the JSON format for public keys:

-```
+```yaml
 #cloud-config

 users:
@@ -300,7 +298,8 @@ users:

 ### write_files

-The `write-file` parameter defines a list of files to create on the local filesystem. Each file is represented as an associative array which has the following keys:
+The `write_files` directive defines a set of files to create on the local filesystem.
+Each item in the list may have the following keys:

 - **path**: Absolute location on disk where contents should be written
 - **content**: Data to write at the provided `path`
@@ -310,14 +309,19 @@ The `write-file` parameter defines a list of files to create on the local filesy
 Explicitly not implemented is the **encoding** attribute.
 The **content** field must represent exactly what should be written to disk.

-```
+```yaml
 #cloud-config
 write_files:
-  - path: /etc/fleet/fleet.conf
+  - path: /etc/resolv.conf
    permissions: 0644
+    owner: root
    content: |
-      verbosity=1
-      metadata="region=us-west,type=ssd"
+      nameserver 8.8.8.8
+  - path: /etc/motd
+    permissions: 0644
+    owner: root
+    content: |
+      Good news, everyone!
 ```

 ### manage_etc_hosts
@@ -327,7 +331,7 @@ Currently, the only supported value is "localhost" which will cause your system'
 to resolve to "127.0.0.1".  This is helpful when the host does not have DNS
 infrastructure in place to resolve its own hostname, for example, when using Vagrant.

-```
+```yaml
 #cloud-config

 manage_etc_hosts: localhost
--- a/Documentation/config-drive.md
+++ b/Documentation/config-drive.md
@@ -14,17 +14,21 @@ The image should be a single FAT or ISO9660 file system with the label

 For example, to wrap up a config named `user_data` in a config drive image:

-    mkdir -p /tmp/new-drive/openstack/latest
-    cp user_data /tmp/new-drive/openstack/latest/user_data
-    mkisofs -R -V config-2 -o configdrive.iso /tmp/new-drive
-    rm -r /tmp/new-drive
+```sh
+mkdir -p /tmp/new-drive/openstack/latest
+cp user_data /tmp/new-drive/openstack/latest/user_data
+mkisofs -R -V config-2 -o configdrive.iso /tmp/new-drive
+rm -r /tmp/new-drive
+```

 ## QEMU virtfs

 One exception to the above, when using QEMU it is possible to skip creating an
 image and use a plain directory containing the same contents:

-    qemu-system-x86_64 \
+```sh
+qemu-system-x86_64 \
    -fsdev local,id=conf,security_model=none,readonly,path=/tmp/new-drive \
    -device virtio-9p-pci,fsdev=conf,mount_tag=config-2 \
    [usual qemu options here...]
+```
--- a/Documentation/debian-interfaces.md
+++ b/Documentation/debian-interfaces.md
@@ -0,0 +1,27 @@
+#Debian Interfaces#
+**WARNING**: This option is EXPERIMENTAL and may change or be removed at any
+point.  
+There is basic support for converting from a Debian network configuration to
+networkd unit files. The -convert-netconf=debian option is used to activate
+this feature.
+
+#convert-netconf#
+Default: ""  
+Read the network config provided in cloud-drive and translate it from the
+specified format into networkd unit files (requires the -from-configdrive
+flag). Currently only supports "debian" which provides support for a small
+subset of the [Debian network configuration]
+(https://wiki.debian.org/NetworkConfiguration). These options include:
+
+- interface config methods
+	- static
+		- address/netmask
+		- gateway
+		- hwaddress
+		- dns-nameservers
+	- dhcp
+		- hwaddress
+	- manual
+	- loopback
+- vlan_raw_device
+- bond-slaves
--- a/3
+++ b/3
@@ -0,0 +1,3 @@
+Alex Crawford <alex.crawford@coreos.com> (@crawford)
+Jonathan Boulle <jonathan.boulle@coreos.com> (@jonboulle)
+Brian Waldon <brian.waldon@coreos.com> (@bcwaldon)
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# coreos-cloudinit
+# coreos-cloudinit [![Build Status](https://travis-ci.org/coreos/coreos-cloudinit.png?branch=master)](https://travis-ci.org/coreos/coreos-cloudinit)

 coreos-cloudinit enables a user to customize CoreOS machines by providing either a cloud-config document or an executable script through user-data.

--- a/14
+++ b/14
@@ -1,6 +1,14 @@
 #!/bin/bash -e

-export GOBIN=${PWD}/bin
-export GOPATH=${PWD}
+ORG_PATH="github.com/coreos"
+REPO_PATH="${ORG_PATH}/coreos-cloudinit"

-go build -o bin/coreos-cloudinit github.com/coreos/coreos-cloudinit
+if [ ! -h gopath/src/${REPO_PATH} ]; then
+	mkdir -p gopath/src/${ORG_PATH}
+	ln -s ../../../.. gopath/src/${REPO_PATH} || exit 255
+fi
+
+export GOBIN=${PWD}/bin
+export GOPATH=${PWD}/gopath
+
+go build -o bin/coreos-cloudinit ${REPO_PATH}
--- a/config/config.go
+++ b/config/config.go
@@ -0,0 +1,198 @@
+package config
+
+import (
+	"fmt"
+	"log"
+	"reflect"
+	"strings"
+
+	"github.com/coreos/coreos-cloudinit/third_party/gopkg.in/yaml.v1"
+)
+
+// CloudConfig encapsulates the entire cloud-config configuration file and maps
+// directly to YAML. Fields that cannot be set in the cloud-config (fields
+// used for internal use) have the YAML tag '-' so that they aren't marshalled.
+type CloudConfig struct {
+	SSHAuthorizedKeys []string `yaml:"ssh_authorized_keys"`
+	Coreos            struct {
+		Etcd   Etcd   `yaml:"etcd"`
+		Fleet  Fleet  `yaml:"fleet"`
+		OEM    OEM    `yaml:"oem"`
+		Update Update `yaml:"update"`
+		Units  []Unit `yaml:"units"`
+	} `yaml:"coreos"`
+	WriteFiles        []File   `yaml:"write_files"`
+	Hostname          string   `yaml:"hostname"`
+	Users             []User   `yaml:"users"`
+	ManageEtcHosts    EtcHosts `yaml:"manage_etc_hosts"`
+	NetworkConfigPath string   `yaml:"-"`
+	NetworkConfig     string   `yaml:"-"`
+}
+
+// NewCloudConfig instantiates a new CloudConfig from the given contents (a
+// string of YAML), returning any error encountered. It will ignore unknown
+// fields but log encountering them.
+func NewCloudConfig(contents string) (*CloudConfig, error) {
+	var cfg CloudConfig
+	err := yaml.Unmarshal([]byte(contents), &cfg)
+	if err != nil {
+		return &cfg, err
+	}
+	warnOnUnrecognizedKeys(contents, log.Printf)
+	return &cfg, nil
+}
+
+func (cc CloudConfig) String() string {
+	bytes, err := yaml.Marshal(cc)
+	if err != nil {
+		return ""
+	}
+
+	stringified := string(bytes)
+	stringified = fmt.Sprintf("#cloud-config\n%s", stringified)
+
+	return stringified
+}
+
+// IsZero returns whether or not the parameter is the zero value for its type.
+// If the parameter is a struct, only the exported fields are considered.
+func IsZero(c interface{}) bool {
+	return isZero(reflect.ValueOf(c))
+}
+
+// AssertValid checks the fields in the structure and makes sure that they
+// contain valid values as specified by the 'valid' flag. Empty fields are
+// implicitly valid.
+func AssertValid(c interface{}) error {
+	ct := reflect.TypeOf(c)
+	cv := reflect.ValueOf(c)
+	for i := 0; i < ct.NumField(); i++ {
+		ft := ct.Field(i)
+		if !isFieldExported(ft) {
+			continue
+		}
+
+		valid := ft.Tag.Get("valid")
+		val := cv.Field(i)
+		if !isValid(val, valid) {
+			return fmt.Errorf("invalid value \"%v\" for option %q (valid options: %q)", val.Interface(), ft.Name, valid)
+		}
+	}
+	return nil
+}
+
+func isZero(v reflect.Value) bool {
+	switch v.Kind() {
+	case reflect.Struct:
+		vt := v.Type()
+		for i := 0; i < v.NumField(); i++ {
+			if isFieldExported(vt.Field(i)) && !isZero(v.Field(i)) {
+				return false
+			}
+		}
+		return true
+	default:
+		return v.Interface() == reflect.Zero(v.Type()).Interface()
+	}
+}
+
+func isFieldExported(f reflect.StructField) bool {
+	return f.PkgPath == ""
+}
+
+func isValid(v reflect.Value, valid string) bool {
+	if valid == "" || isZero(v) {
+		return true
+	}
+	vs := fmt.Sprintf("%v", v.Interface())
+	for _, valid := range strings.Split(valid, ",") {
+		if vs == valid {
+			return true
+		}
+	}
+	return false
+}
+
+type warner func(format string, v ...interface{})
+
+// warnOnUnrecognizedKeys parses the contents of a cloud-config file and calls
+// warn(msg, key) for every unrecognized key (i.e. those not present in CloudConfig)
+func warnOnUnrecognizedKeys(contents string, warn warner) {
+	// Generate a map of all understood cloud config options
+	var cc map[string]interface{}
+	b, _ := yaml.Marshal(&CloudConfig{})
+	yaml.Unmarshal(b, &cc)
+
+	// Now unmarshal the entire provided contents
+	var c map[string]interface{}
+	yaml.Unmarshal([]byte(contents), &c)
+
+	// Check that every key in the contents exists in the cloud config
+	for k, _ := range c {
+		if _, ok := cc[k]; !ok {
+			warn("Warning: unrecognized key %q in provided cloud config - ignoring section", k)
+		}
+	}
+
+	// Check for unrecognized coreos options, if any are set
+	if coreos, ok := c["coreos"]; ok {
+		if set, ok := coreos.(map[interface{}]interface{}); ok {
+			known := cc["coreos"].(map[interface{}]interface{})
+			for k, _ := range set {
+				if key, ok := k.(string); ok {
+					if _, ok := known[key]; !ok {
+						warn("Warning: unrecognized key %q in coreos section of provided cloud config - ignoring", key)
+					}
+				} else {
+					warn("Warning: unrecognized key %q in coreos section of provided cloud config - ignoring", k)
+				}
+			}
+		}
+	}
+
+	// Check for any badly-specified users, if any are set
+	if users, ok := c["users"]; ok {
+		var known map[string]interface{}
+		b, _ := yaml.Marshal(&User{})
+		yaml.Unmarshal(b, &known)
+
+		if set, ok := users.([]interface{}); ok {
+			for _, u := range set {
+				if user, ok := u.(map[interface{}]interface{}); ok {
+					for k, _ := range user {
+						if key, ok := k.(string); ok {
+							if _, ok := known[key]; !ok {
+								warn("Warning: unrecognized key %q in user section of cloud config - ignoring", key)
+							}
+						} else {
+							warn("Warning: unrecognized key %q in user section of cloud config - ignoring", k)
+						}
+					}
+				}
+			}
+		}
+	}
+
+	// Check for any badly-specified files, if any are set
+	if files, ok := c["write_files"]; ok {
+		var known map[string]interface{}
+		b, _ := yaml.Marshal(&File{})
+		yaml.Unmarshal(b, &known)
+
+		if set, ok := files.([]interface{}); ok {
+			for _, f := range set {
+				if file, ok := f.(map[interface{}]interface{}); ok {
+					for k, _ := range file {
+						if key, ok := k.(string); ok {
+							if _, ok := known[key]; !ok {
+								warn("Warning: unrecognized key %q in file section of cloud config - ignoring", key)
+							}
+						} else {
+							warn("Warning: unrecognized key %q in file section of cloud config - ignoring", k)
+						}
+					}
+				}
+			}
+		}
+	}
+}
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -0,0 +1,473 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestIsZero(t *testing.T) {
+	for _, tt := range []struct {
+		c     interface{}
+		empty bool
+	}{
+		{struct{}{}, true},
+		{struct{ a, b string }{}, true},
+		{struct{ A, b string }{}, true},
+		{struct{ A, B string }{}, true},
+		{struct{ A string }{A: "hello"}, false},
+		{struct{ A int }{}, true},
+		{struct{ A int }{A: 1}, false},
+	} {
+		if empty := IsZero(tt.c); tt.empty != empty {
+			t.Errorf("bad result (%q): want %q, got %q", tt.c, tt.empty, empty)
+		}
+	}
+}
+
+func TestAssertValid(t *testing.T) {
+	for _, tt := range []struct {
+		c   interface{}
+		err error
+	}{
+		{struct{}{}, nil},
+		{struct {
+			A, b string `valid:"1,2"`
+		}{}, nil},
+		{struct {
+			A, b string `valid:"1,2"`
+		}{A: "1", b: "2"}, nil},
+		{struct {
+			A, b string `valid:"1,2"`
+		}{A: "1", b: "hello"}, nil},
+		{struct {
+			A, b string `valid:"1,2"`
+		}{A: "hello", b: "2"}, errors.New("invalid value \"hello\" for option \"A\" (valid options: \"1,2\")")},
+		{struct {
+			A, b int `valid:"1,2"`
+		}{}, nil},
+		{struct {
+			A, b int `valid:"1,2"`
+		}{A: 1, b: 2}, nil},
+		{struct {
+			A, b int `valid:"1,2"`
+		}{A: 1, b: 9}, nil},
+		{struct {
+			A, b int `valid:"1,2"`
+		}{A: 9, b: 2}, errors.New("invalid value \"9\" for option \"A\" (valid options: \"1,2\")")},
+	} {
+		if err := AssertValid(tt.c); !reflect.DeepEqual(tt.err, err) {
+			t.Errorf("bad result (%q): want %q, got %q", tt.c, tt.err, err)
+		}
+	}
+}
+
+func TestCloudConfigInvalidKeys(t *testing.T) {
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("panic while instantiating CloudConfig with nil keys: %v", r)
+		}
+	}()
+
+	for _, tt := range []struct {
+		contents string
+	}{
+		{"coreos:"},
+		{"ssh_authorized_keys:"},
+		{"ssh_authorized_keys:\n  -"},
+		{"ssh_authorized_keys:\n  - 0:"},
+		{"write_files:"},
+		{"write_files:\n  -"},
+		{"write_files:\n  - 0:"},
+		{"users:"},
+		{"users:\n  -"},
+		{"users:\n  - 0:"},
+	} {
+		_, err := NewCloudConfig(tt.contents)
+		if err != nil {
+			t.Fatalf("error instantiating CloudConfig with invalid keys: %v", err)
+		}
+	}
+}
+
+func TestCloudConfigUnknownKeys(t *testing.T) {
+	contents := `
+coreos: 
+  etcd:
+    discovery: "https://discovery.etcd.io/827c73219eeb2fa5530027c37bf18877"
+  coreos_unknown:
+    foo: "bar"
+section_unknown:
+  dunno:
+    something
+bare_unknown:
+  bar
+write_files:
+  - content: fun
+    path: /var/party
+    file_unknown: nofun
+users:
+  - name: fry
+    passwd: somehash
+    user_unknown: philip
+hostname:
+  foo
+`
+	cfg, err := NewCloudConfig(contents)
+	if err != nil {
+		t.Fatalf("error instantiating CloudConfig with unknown keys: %v", err)
+	}
+	if cfg.Hostname != "foo" {
+		t.Fatalf("hostname not correctly set when invalid keys are present")
+	}
+	if cfg.Coreos.Etcd.Discovery != "https://discovery.etcd.io/827c73219eeb2fa5530027c37bf18877" {
+		t.Fatalf("etcd section not correctly set when invalid keys are present")
+	}
+	if len(cfg.WriteFiles) < 1 || cfg.WriteFiles[0].Content != "fun" || cfg.WriteFiles[0].Path != "/var/party" {
+		t.Fatalf("write_files section not correctly set when invalid keys are present")
+	}
+	if len(cfg.Users) < 1 || cfg.Users[0].Name != "fry" || cfg.Users[0].PasswordHash != "somehash" {
+		t.Fatalf("users section not correctly set when invalid keys are present")
+	}
+
+	var warnings string
+	catchWarn := func(f string, v ...interface{}) {
+		warnings += fmt.Sprintf(f, v...)
+	}
+
+	warnOnUnrecognizedKeys(contents, catchWarn)
+
+	if !strings.Contains(warnings, "coreos_unknown") {
+		t.Errorf("warnings did not catch unrecognized coreos option coreos_unknown")
+	}
+	if !strings.Contains(warnings, "bare_unknown") {
+		t.Errorf("warnings did not catch unrecognized key bare_unknown")
+	}
+	if !strings.Contains(warnings, "section_unknown") {
+		t.Errorf("warnings did not catch unrecognized key section_unknown")
+	}
+	if !strings.Contains(warnings, "user_unknown") {
+		t.Errorf("warnings did not catch unrecognized user key user_unknown")
+	}
+	if !strings.Contains(warnings, "file_unknown") {
+		t.Errorf("warnings did not catch unrecognized file key file_unknown")
+	}
+}
+
+// Assert that the parsing of a cloud config file "generally works"
+func TestCloudConfigEmpty(t *testing.T) {
+	cfg, err := NewCloudConfig("")
+	if err != nil {
+		t.Fatalf("Encountered unexpected error :%v", err)
+	}
+
+	keys := cfg.SSHAuthorizedKeys
+	if len(keys) != 0 {
+		t.Error("Parsed incorrect number of SSH keys")
+	}
+
+	if len(cfg.WriteFiles) != 0 {
+		t.Error("Expected zero WriteFiles")
+	}
+
+	if cfg.Hostname != "" {
+		t.Errorf("Expected hostname to be empty, got '%s'", cfg.Hostname)
+	}
+}
+
+// Assert that the parsing of a cloud config file "generally works"
+func TestCloudConfig(t *testing.T) {
+	contents := `
+coreos: 
+  etcd:
+    discovery: "https://discovery.etcd.io/827c73219eeb2fa5530027c37bf18877"
+  update:
+    reboot-strategy: reboot
+  units:
+    - name: 50-eth0.network
+      runtime: yes
+      content: '[Match]
+ 
+    Name=eth47
+ 
+ 
+    [Network]
+ 
+    Address=10.209.171.177/19
+ 
+'
+  oem:
+    id: rackspace
+    name: Rackspace Cloud Servers
+    version-id: 168.0.0
+    home-url: https://www.rackspace.com/cloud/servers/
+    bug-report-url: https://github.com/coreos/coreos-overlay
+ssh_authorized_keys:
+  - foobar
+  - foobaz
+write_files:
+  - content: |
+      penny
+      elroy
+    path: /etc/dogepack.conf
+    permissions: '0644'
+    owner: root:dogepack
+hostname: trontastic
+`
+	cfg, err := NewCloudConfig(contents)
+	if err != nil {
+		t.Fatalf("Encountered unexpected error :%v", err)
+	}
+
+	keys := cfg.SSHAuthorizedKeys
+	if len(keys) != 2 {
+		t.Error("Parsed incorrect number of SSH keys")
+	} else if keys[0] != "foobar" {
+		t.Error("Expected first SSH key to be 'foobar'")
+	} else if keys[1] != "foobaz" {
+		t.Error("Expected first SSH key to be 'foobaz'")
+	}
+
+	if len(cfg.WriteFiles) != 1 {
+		t.Error("Failed to parse correct number of write_files")
+	} else {
+		wf := cfg.WriteFiles[0]
+		if wf.Content != "penny\nelroy\n" {
+			t.Errorf("WriteFile has incorrect contents '%s'", wf.Content)
+		}
+		if wf.Encoding != "" {
+			t.Errorf("WriteFile has incorrect encoding %s", wf.Encoding)
+		}
+		if wf.RawFilePermissions != "0644" {
+			t.Errorf("WriteFile has incorrect permissions %s", wf.RawFilePermissions)
+		}
+		if wf.Path != "/etc/dogepack.conf" {
+			t.Errorf("WriteFile has incorrect path %s", wf.Path)
+		}
+		if wf.Owner != "root:dogepack" {
+			t.Errorf("WriteFile has incorrect owner %s", wf.Owner)
+		}
+	}
+
+	if len(cfg.Coreos.Units) != 1 {
+		t.Error("Failed to parse correct number of units")
+	} else {
+		u := cfg.Coreos.Units[0]
+		expect := `[Match]
+Name=eth47
+
+[Network]
+Address=10.209.171.177/19
+`
+		if u.Content != expect {
+			t.Errorf("Unit has incorrect contents '%s'.\nExpected '%s'.", u.Content, expect)
+		}
+		if u.Runtime != true {
+			t.Errorf("Unit has incorrect runtime value")
+		}
+		if u.Name != "50-eth0.network" {
+			t.Errorf("Unit has incorrect name %s", u.Name)
+		}
+		if u.Type() != "network" {
+			t.Errorf("Unit has incorrect type '%s'", u.Type())
+		}
+	}
+
+	if cfg.Coreos.OEM.ID != "rackspace" {
+		t.Errorf("Failed parsing coreos.oem. Expected ID 'rackspace', got %q.", cfg.Coreos.OEM.ID)
+	}
+
+	if cfg.Hostname != "trontastic" {
+		t.Errorf("Failed to parse hostname")
+	}
+	if cfg.Coreos.Update.RebootStrategy != "reboot" {
+		t.Errorf("Failed to parse locksmith strategy")
+	}
+}
+
+// Assert that our interface conversion doesn't panic
+func TestCloudConfigKeysNotList(t *testing.T) {
+	contents := `
+ssh_authorized_keys:
+  - foo: bar
+`
+	cfg, err := NewCloudConfig(contents)
+	if err != nil {
+		t.Fatalf("Encountered unexpected error: %v", err)
+	}
+
+	keys := cfg.SSHAuthorizedKeys
+	if len(keys) != 0 {
+		t.Error("Parsed incorrect number of SSH keys")
+	}
+}
+
+func TestCloudConfigSerializationHeader(t *testing.T) {
+	cfg, _ := NewCloudConfig("")
+	contents := cfg.String()
+	header := strings.SplitN(contents, "\n", 2)[0]
+	if header != "#cloud-config" {
+		t.Fatalf("Serialized config did not have expected header")
+	}
+}
+
+// TestDropInIgnored asserts that users are unable to set DropIn=True on units
+func TestDropInIgnored(t *testing.T) {
+	contents := `
+coreos:
+  units:
+    - name: test
+      dropin: true
+`
+	cfg, err := NewCloudConfig(contents)
+	if err != nil || len(cfg.Coreos.Units) != 1 {
+		t.Fatalf("Encountered unexpected error: %v", err)
+	}
+	if len(cfg.Coreos.Units) != 1 || cfg.Coreos.Units[0].Name != "test" {
+		t.Fatalf("Expected 1 unit, but got %d: %v", len(cfg.Coreos.Units), cfg.Coreos.Units)
+	}
+	if cfg.Coreos.Units[0].DropIn {
+		t.Errorf("dropin option on unit in cloud-config was not ignored!")
+	}
+}
+
+func TestCloudConfigUsers(t *testing.T) {
+	contents := `
+users:
+  - name: elroy
+    passwd: somehash
+    ssh-authorized-keys:
+      - somekey
+    gecos: arbitrary comment
+    homedir: /home/place
+    no-create-home: yes
+    primary-group: things
+    groups:
+      - ping
+      - pong
+    no-user-group: true
+    system: y
+    no-log-init: True
+`
+	cfg, err := NewCloudConfig(contents)
+	if err != nil {
+		t.Fatalf("Encountered unexpected error: %v", err)
+	}
+
+	if len(cfg.Users) != 1 {
+		t.Fatalf("Parsed %d users, expected 1", cfg.Users)
+	}
+
+	user := cfg.Users[0]
+
+	if user.Name != "elroy" {
+		t.Errorf("User name is %q, expected 'elroy'", user.Name)
+	}
+
+	if user.PasswordHash != "somehash" {
+		t.Errorf("User passwd is %q, expected 'somehash'", user.PasswordHash)
+	}
+
+	if keys := user.SSHAuthorizedKeys; len(keys) != 1 {
+		t.Errorf("Parsed %d ssh keys, expected 1", len(keys))
+	} else {
+		key := user.SSHAuthorizedKeys[0]
+		if key != "somekey" {
+			t.Errorf("User SSH key is %q, expected 'somekey'", key)
+		}
+	}
+
+	if user.GECOS != "arbitrary comment" {
+		t.Errorf("Failed to parse gecos field, got %q", user.GECOS)
+	}
+
+	if user.Homedir != "/home/place" {
+		t.Errorf("Failed to parse homedir field, got %q", user.Homedir)
+	}
+
+	if !user.NoCreateHome {
+		t.Errorf("Failed to parse no-create-home field")
+	}
+
+	if user.PrimaryGroup != "things" {
+		t.Errorf("Failed to parse primary-group field, got %q", user.PrimaryGroup)
+	}
+
+	if len(user.Groups) != 2 {
+		t.Errorf("Failed to parse 2 goups, got %d", len(user.Groups))
+	} else {
+		if user.Groups[0] != "ping" {
+			t.Errorf("First group was %q, not expected value 'ping'", user.Groups[0])
+		}
+		if user.Groups[1] != "pong" {
+			t.Errorf("First group was %q, not expected value 'pong'", user.Groups[1])
+		}
+	}
+
+	if !user.NoUserGroup {
+		t.Errorf("Failed to parse no-user-group field")
+	}
+
+	if !user.System {
+		t.Errorf("Failed to parse system field")
+	}
+
+	if !user.NoLogInit {
+		t.Errorf("Failed to parse no-log-init field")
+	}
+}
+
+func TestCloudConfigUsersGithubUser(t *testing.T) {
+
+	contents := `
+users:
+  - name: elroy
+    coreos-ssh-import-github: bcwaldon
+`
+	cfg, err := NewCloudConfig(contents)
+	if err != nil {
+		t.Fatalf("Encountered unexpected error: %v", err)
+	}
+
+	if len(cfg.Users) != 1 {
+		t.Fatalf("Parsed %d users, expected 1", cfg.Users)
+	}
+
+	user := cfg.Users[0]
+
+	if user.Name != "elroy" {
+		t.Errorf("User name is %q, expected 'elroy'", user.Name)
+	}
+
+	if user.SSHImportGithubUser != "bcwaldon" {
+		t.Errorf("github user is %q, expected 'bcwaldon'", user.SSHImportGithubUser)
+	}
+}
+
+func TestCloudConfigUsersSSHImportURL(t *testing.T) {
+	contents := `
+users:
+  - name: elroy
+    coreos-ssh-import-url: https://token:x-auth-token@github.enterprise.com/api/v3/polvi/keys
+`
+	cfg, err := NewCloudConfig(contents)
+	if err != nil {
+		t.Fatalf("Encountered unexpected error: %v", err)
+	}
+
+	if len(cfg.Users) != 1 {
+		t.Fatalf("Parsed %d users, expected 1", cfg.Users)
+	}
+
+	user := cfg.Users[0]
+
+	if user.Name != "elroy" {
+		t.Errorf("User name is %q, expected 'elroy'", user.Name)
+	}
+
+	if user.SSHImportURL != "https://token:x-auth-token@github.enterprise.com/api/v3/polvi/keys" {
+		t.Errorf("ssh import url is %q, expected 'https://token:x-auth-token@github.enterprise.com/api/v3/polvi/keys'", user.SSHImportURL)
+	}
+}
--- a/config/etc_hosts.go
+++ b/config/etc_hosts.go
@@ -0,0 +1,3 @@
+package config
+
+type EtcHosts string
--- a/config/etcd.go
+++ b/config/etcd.go
@@ -0,0 +1,32 @@
+package config
+
+type Etcd struct {
+	Addr                string `yaml:"addr"                  env:"ETCD_ADDR"`
+	BindAddr            string `yaml:"bind-addr"             env:"ETCD_BIND_ADDR"`
+	CAFile              string `yaml:"ca-file"               env:"ETCD_CA_FILE"`
+	CertFile            string `yaml:"cert-file"             env:"ETCD_CERT_FILE"`
+	ClusterActiveSize   string `yaml:"cluster-active-size"   env:"ETCD_CLUSTER_ACTIVE_SIZE"`
+	ClusterRemoveDelay  string `yaml:"cluster-remove-delay"  env:"ETCD_CLUSTER_REMOVE_DELAY"`
+	ClusterSyncInterval string `yaml:"cluster-sync-interval" env:"ETCD_CLUSTER_SYNC_INTERVAL"`
+	Cors                string `yaml:"cors"                  env:"ETCD_CORS"`
+	CPUProfileFile      string `yaml:"cpu-profile-file"      env:"ETCD_CPU_PROFILE_FILE"`
+	DataDir             string `yaml:"data-dir"              env:"ETCD_DATA_DIR"`
+	Discovery           string `yaml:"discovery"             env:"ETCD_DISCOVERY"`
+	HTTPReadTimeout     string `yaml:"http-read-timeout"     env:"ETCD_HTTP_READ_TIMEOUT"`
+	HTTPWriteTimeout    string `yaml:"http-write-timeout"    env:"ETCD_HTTP_WRITE_TIMEOUT"`
+	KeyFile             string `yaml:"key-file"              env:"ETCD_KEY_FILE"`
+	MaxClusterSize      string `yaml:"max-cluster-size"      env:"ETCD_MAX_CLUSTER_SIZE"`
+	MaxResultBuffer     string `yaml:"max-result-buffer"     env:"ETCD_MAX_RESULT_BUFFER"`
+	MaxRetryAttempts    string `yaml:"max-retry-attempts"    env:"ETCD_MAX_RETRY_ATTEMPTS"`
+	Name                string `yaml:"name"                  env:"ETCD_NAME"`
+	PeerAddr            string `yaml:"peer-addr"             env:"ETCD_PEER_ADDR"`
+	PeerBindAddr        string `yaml:"peer-bind-addr"        env:"ETCD_PEER_BIND_ADDR"`
+	PeerCAFile          string `yaml:"peer-ca-file"          env:"ETCD_PEER_CA_FILE"`
+	PeerCertFile        string `yaml:"peer-cert-file"        env:"ETCD_PEER_CERT_FILE"`
+	PeerKeyFile         string `yaml:"peer-key-file"         env:"ETCD_PEER_KEY_FILE"`
+	Peers               string `yaml:"peers"                 env:"ETCD_PEERS"`
+	PeersFile           string `yaml:"peers-file"            env:"ETCD_PEERS_FILE"`
+	Snapshot            string `yaml:"snapshot"              env:"ETCD_SNAPSHOT"`
+	Verbose             string `yaml:"verbose"               env:"ETCD_VERBOSE"`
+	VeryVerbose         string `yaml:"very-verbose"          env:"ETCD_VERY_VERBOSE"`
+}
--- a/config/file.go
+++ b/config/file.go
@@ -0,0 +1,9 @@
+package config
+
+type File struct {
+	Encoding           string `yaml:"-"`
+	Content            string `yaml:"content"`
+	Owner              string `yaml:"owner"`
+	Path               string `yaml:"path"`
+	RawFilePermissions string `yaml:"permissions"`
+}
--- a/config/fleet.go
+++ b/config/fleet.go
@@ -0,0 +1,14 @@
+package config
+
+type Fleet struct {
+	AgentTTL                string `yaml:"agent-ttl"                 env:"FLEET_AGENT_TTL"`
+	EngineReconcileInterval string `yaml:"engine-reconcile-interval" env:"FLEET_ENGINE_RECONCILE_INTERVAL"`
+	EtcdCAFile              string `yaml:"etcd-cafile"               env:"FLEET_ETCD_CAFILE"`
+	EtcdCertFile            string `yaml:"etcd-certfile"             env:"FLEET_ETCD_CERTFILE"`
+	EtcdKeyFile             string `yaml:"etcd-keyfile"              env:"FLEET_ETCD_KEYFILE"`
+	EtcdRequestTimeout      string `yaml:"etcd-request-timeout"      env:"FLEET_ETCD_REQUEST_TIMEOUT"`
+	EtcdServers             string `yaml:"etcd-servers"              env:"FLEET_ETCD_SERVERS"`
+	Metadata                string `yaml:"metadata"                  env:"FLEET_METADATA"`
+	PublicIP                string `yaml:"public-ip"                 env:"FLEET_PUBLIC_IP"`
+	Verbosity               string `yaml:"verbosity"                 env:"FLEET_VERBOSITY"`
+}
--- a/config/oem.go
+++ b/config/oem.go
@@ -0,0 +1,9 @@
+package config
+
+type OEM struct {
+	ID           string `yaml:"id"`
+	Name         string `yaml:"name"`
+	VersionID    string `yaml:"version-id"`
+	HomeURL      string `yaml:"home-url"`
+	BugReportURL string `yaml:"bug-report-url"`
+}
--- a/config/unit.go
+++ b/config/unit.go
@@ -0,0 +1,34 @@
+package config
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+type Unit struct {
+	Name    string `yaml:"name"`
+	Mask    bool   `yaml:"mask"`
+	Enable  bool   `yaml:"enable"`
+	Runtime bool   `yaml:"runtime"`
+	Content string `yaml:"content"`
+	Command string `yaml:"command"`
+
+	// For drop-in units, a cloudinit.conf is generated.
+	// This is currently unbound in YAML (and hence unsettable in cloud-config files)
+	// until the correct behaviour for multiple drop-in units is determined.
+	DropIn bool `yaml:"-"`
+}
+
+func (u *Unit) Type() string {
+	ext := filepath.Ext(u.Name)
+	return strings.TrimLeft(ext, ".")
+}
+
+func (u *Unit) Group() string {
+	switch u.Type() {
+	case "network", "netdev", "link":
+		return "network"
+	default:
+		return "system"
+	}
+}
--- a/config/update.go
+++ b/config/update.go
@@ -0,0 +1,7 @@
+package config
+
+type Update struct {
+	RebootStrategy string `yaml:"reboot-strategy" env:"REBOOT_STRATEGY" valid:"best-effort,etcd-lock,reboot,off"`
+	Group          string `yaml:"group"           env:"GROUP"`
+	Server         string `yaml:"server"          env:"SERVER"`
+}
--- a/config/user.go
+++ b/config/user.go
@@ -0,0 +1,17 @@
+package config
+
+type User struct {
+	Name                string   `yaml:"name"`
+	PasswordHash        string   `yaml:"passwd"`
+	SSHAuthorizedKeys   []string `yaml:"ssh-authorized-keys"`
+	SSHImportGithubUser string   `yaml:"coreos-ssh-import-github"`
+	SSHImportURL        string   `yaml:"coreos-ssh-import-url"`
+	GECOS               string   `yaml:"gecos"`
+	Homedir             string   `yaml:"homedir"`
+	NoCreateHome        bool     `yaml:"no-create-home"`
+	PrimaryGroup        string   `yaml:"primary-group"`
+	Groups              []string `yaml:"groups"`
+	NoUserGroup         bool     `yaml:"no-user-group"`
+	System              bool     `yaml:"system"`
+	NoLogInit           bool     `yaml:"no-log-init"`
+}
--- a/coreos-cloudinit.go
+++ b/coreos-cloudinit.go
@@ -3,112 +3,351 @@ package main
 import (
 	"flag"
 	"fmt"
-	"log"
 	"os"
+	"sync"
+	"time"

+	"github.com/coreos/coreos-cloudinit/config"
 	"github.com/coreos/coreos-cloudinit/datasource"
+	"github.com/coreos/coreos-cloudinit/datasource/configdrive"
+	"github.com/coreos/coreos-cloudinit/datasource/file"
+	"github.com/coreos/coreos-cloudinit/datasource/metadata/cloudsigma"
+	"github.com/coreos/coreos-cloudinit/datasource/metadata/digitalocean"
+	"github.com/coreos/coreos-cloudinit/datasource/metadata/ec2"
+	"github.com/coreos/coreos-cloudinit/datasource/proc_cmdline"
+	"github.com/coreos/coreos-cloudinit/datasource/url"
 	"github.com/coreos/coreos-cloudinit/initialize"
+	"github.com/coreos/coreos-cloudinit/pkg"
 	"github.com/coreos/coreos-cloudinit/system"
 )

-const version = "0.6.0"
+const (
+	version               = "0.10.4"
+	datasourceInterval    = 100 * time.Millisecond
+	datasourceMaxInterval = 30 * time.Second
+	datasourceTimeout     = 5 * time.Minute
+)
+
+var (
+	flags = struct {
+		printVersion  bool
+		ignoreFailure bool
+		sources       struct {
+			file                        string
+			configDrive                 string
+			metadataService             bool
+			ec2MetadataService          string
+			cloudSigmaMetadataService   bool
+			digitalOceanMetadataService string
+			url                         string
+			procCmdLine                 bool
+		}
+		convertNetconf string
+		workspace      string
+		sshKeyName     string
+		oem            string
+	}{}
+)
+
+func init() {
+	flag.BoolVar(&flags.printVersion, "version", false, "Print the version and exit")
+	flag.BoolVar(&flags.ignoreFailure, "ignore-failure", false, "Exits with 0 status in the event of malformed input from user-data")
+	flag.StringVar(&flags.sources.file, "from-file", "", "Read user-data from provided file")
+	flag.StringVar(&flags.sources.configDrive, "from-configdrive", "", "Read data from provided cloud-drive directory")
+	flag.BoolVar(&flags.sources.metadataService, "from-metadata-service", false, "[DEPRECATED - Use -from-ec2-metadata] Download data from metadata service")
+	flag.StringVar(&flags.sources.ec2MetadataService, "from-ec2-metadata", "", "Download EC2 data from the provided url")
+	flag.BoolVar(&flags.sources.cloudSigmaMetadataService, "from-cloudsigma-metadata", false, "Download data from CloudSigma server context")
+	flag.StringVar(&flags.sources.digitalOceanMetadataService, "from-digitalocean-metadata", "", "Download DigitalOcean data from the provided url")
+	flag.StringVar(&flags.sources.url, "from-url", "", "Download user-data from provided url")
+	flag.BoolVar(&flags.sources.procCmdLine, "from-proc-cmdline", false, fmt.Sprintf("Parse %s for '%s=<url>', using the cloud-config served by an HTTP GET to <url>", proc_cmdline.ProcCmdlineLocation, proc_cmdline.ProcCmdlineCloudConfigFlag))
+	flag.StringVar(&flags.oem, "oem", "", "Use the settings specific to the provided OEM")
+	flag.StringVar(&flags.convertNetconf, "convert-netconf", "", "Read the network config provided in cloud-drive and translate it from the specified format into networkd unit files")
+	flag.StringVar(&flags.workspace, "workspace", "/var/lib/coreos-cloudinit", "Base directory coreos-cloudinit should use to store data")
+	flag.StringVar(&flags.sshKeyName, "ssh-key-name", initialize.DefaultSSHKeyName, "Add SSH keys to the system with the given name")
+}
+
+type oemConfig map[string]string
+
+var (
+	oemConfigs = map[string]oemConfig{
+		"digitalocean": oemConfig{
+			"from-digitalocean-metadata": "http://169.254.169.254/",
+			"convert-netconf":            "digitalocean",
+		},
+		"ec2-compat": oemConfig{
+			"from-ec2-metadata": "http://169.254.169.254/",
+			"from-configdrive":  "/media/configdrive",
+		},
+		"rackspace-onmetal": oemConfig{
+			"from-configdrive": "/media/configdrive",
+			"convert-netconf":  "debian",
+		},
+	}
+)

 func main() {
-	var printVersion bool
-	flag.BoolVar(&printVersion, "version", false, "Print the version and exit")
-
-	var ignoreFailure bool
-	flag.BoolVar(&ignoreFailure, "ignore-failure", false, "Exits with 0 status in the event of malformed input from user-data")
-
-	var file string
-	flag.StringVar(&file, "from-file", "", "Read user-data from provided file")
-
-	var url string
-	flag.StringVar(&url, "from-url", "", "Download user-data from provided url")
-
-	var useProcCmdline bool
-	flag.BoolVar(&useProcCmdline, "from-proc-cmdline", false, fmt.Sprintf("Parse %s for '%s=<url>', using the cloud-config served by an HTTP GET to <url>", datasource.ProcCmdlineLocation, datasource.ProcCmdlineCloudConfigFlag))
-
-	var workspace string
-	flag.StringVar(&workspace, "workspace", "/var/lib/coreos-cloudinit", "Base directory coreos-cloudinit should use to store data")
-
-	var sshKeyName string
-	flag.StringVar(&sshKeyName, "ssh-key-name", initialize.DefaultSSHKeyName, "Add SSH keys to the system with the given name")
+	failure := false

 	flag.Parse()

-	if printVersion == true {
+	if c, ok := oemConfigs[flags.oem]; ok {
+		for k, v := range c {
+			flag.Set(k, v)
+		}
+	} else if flags.oem != "" {
+		oems := make([]string, 0, len(oemConfigs))
+		for k := range oemConfigs {
+			oems = append(oems, k)
+		}
+		fmt.Printf("Invalid option to --oem: %q. Supported options: %q\n", flags.oem, oems)
+		os.Exit(2)
+	}
+
+	if flags.printVersion == true {
 		fmt.Printf("coreos-cloudinit version %s\n", version)
 		os.Exit(0)
 	}

-	if file != "" && url != "" && !useProcCmdline {
-		fmt.Println("Provide one of --from-file, --from-url or --from-proc-cmdline")
+	switch flags.convertNetconf {
+	case "":
+	case "debian":
+	case "digitalocean":
+	default:
+		fmt.Printf("Invalid option to -convert-netconf: '%s'. Supported options: 'debian, digitalocean'\n", flags.convertNetconf)
+		os.Exit(2)
+	}
+
+	dss := getDatasources()
+	if len(dss) == 0 {
+		fmt.Println("Provide at least one of --from-file, --from-configdrive, --from-ec2-metadata, --from-cloudsigma-metadata, --from-url or --from-proc-cmdline")
+		os.Exit(2)
+	}
+
+	ds := selectDatasource(dss)
+	if ds == nil {
+		fmt.Println("No datasources available in time")
 		os.Exit(1)
 	}

-	var ds datasource.Datasource
-	if file != "" {
-		ds = datasource.NewLocalFile(file)
-	} else if url != "" {
-		ds = datasource.NewMetadataService(url)
-	} else if useProcCmdline {
-		ds = datasource.NewProcCmdline()
-	} else {
-		fmt.Println("Provide one of --from-file, --from-url or --from-proc-cmdline")
-		os.Exit(1)
-	}
-
-	log.Printf("Fetching user-data from datasource of type %q", ds.Type())
-	userdataBytes, err := ds.Fetch()
+	fmt.Printf("Fetching user-data from datasource of type %q\n", ds.Type())
+	userdataBytes, err := ds.FetchUserdata()
 	if err != nil {
-		log.Printf("Failed fetching user-data from datasource: %v", err)
-		if ignoreFailure {
-			os.Exit(0)
-		} else {
+		fmt.Printf("Failed fetching user-data from datasource: %v\nContinuing...\n", err)
+		failure = true
+	}
+
+	fmt.Printf("Fetching meta-data from datasource of type %q\n", ds.Type())
+	metadataBytes, err := ds.FetchMetadata()
+	if err != nil {
+		fmt.Printf("Failed fetching meta-data from datasource: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Extract IPv4 addresses from metadata if possible
+	var subs map[string]string
+	if len(metadataBytes) > 0 {
+		subs, err = initialize.ExtractIPsFromMetadata(metadataBytes)
+		if err != nil {
+			fmt.Printf("Failed extracting IPs from meta-data: %v\n", err)
 			os.Exit(1)
 		}
 	}

-	if len(userdataBytes) == 0 {
-		log.Printf("No user data to handle, exiting.")
-		os.Exit(0)
-	}
+	// Apply environment to user-data
+	env := initialize.NewEnvironment("/", ds.ConfigRoot(), flags.workspace, flags.convertNetconf, flags.sshKeyName, subs)
+	userdata := env.Apply(string(userdataBytes))

-	env := initialize.NewEnvironment("/", workspace)
-
-	userdata := string(userdataBytes)
-	userdata = env.Apply(userdata)
-
-	parsed, err := initialize.ParseUserData(userdata)
-	if err != nil {
-		log.Printf("Failed parsing user-data: %v", err)
-		if ignoreFailure {
-			os.Exit(0)
-		} else {
+	var ccm, ccu *config.CloudConfig
+	var script *system.Script
+	if ccm, err = initialize.ParseMetaData(string(metadataBytes)); err != nil {
+		fmt.Printf("Failed to parse meta-data: %v\n", err)
 		os.Exit(1)
 	}
-	}

-	err = initialize.PrepWorkspace(env.Workspace())
+	if ccm != nil && flags.convertNetconf != "" {
+		fmt.Printf("Fetching network config from datasource of type %q\n", ds.Type())
+		netconfBytes, err := ds.FetchNetworkConfig(ccm.NetworkConfigPath)
 		if err != nil {
-		log.Fatalf("Failed preparing workspace: %v", err)
+			fmt.Printf("Failed fetching network config from datasource: %v\n", err)
+			os.Exit(1)
+		}
+		ccm.NetworkConfig = string(netconfBytes)
 	}

-	switch t := parsed.(type) {
-	case initialize.CloudConfig:
-		err = initialize.Apply(t, env)
+	if ud, err := initialize.ParseUserData(userdata); err != nil {
+		fmt.Printf("Failed to parse user-data: %v\nContinuing...\n", err)
+		failure = true
+	} else {
+		switch t := ud.(type) {
+		case *config.CloudConfig:
+			ccu = t
 		case system.Script:
-		var path string
-		path, err = initialize.PersistScriptInWorkspace(t, env.Workspace())
+			script = &t
+		}
+	}
+
+	var cc *config.CloudConfig
+	if ccm != nil && ccu != nil {
+		fmt.Println("Merging cloud-config from meta-data and user-data")
+		merged := mergeCloudConfig(*ccm, *ccu)
+		cc = &merged
+	} else if ccm != nil && ccu == nil {
+		fmt.Println("Processing cloud-config from meta-data")
+		cc = ccm
+	} else if ccm == nil && ccu != nil {
+		fmt.Println("Processing cloud-config from user-data")
+		cc = ccu
+	} else {
+		fmt.Println("No cloud-config data to handle.")
+	}
+
+	if cc != nil {
+		if err = initialize.Apply(*cc, env); err != nil {
+			fmt.Printf("Failed to apply cloud-config: %v\n", err)
+			os.Exit(1)
+		}
+	}
+
+	if script != nil {
+		if err = runScript(*script, env); err != nil {
+			fmt.Printf("Failed to run script: %v\n", err)
+			os.Exit(1)
+		}
+	}
+
+	if failure && !flags.ignoreFailure {
+		os.Exit(1)
+	}
+}
+
+// mergeCloudConfig merges certain options from mdcc (a CloudConfig derived from
+// meta-data) onto udcc (a CloudConfig derived from user-data), if they are
+// not already set on udcc (i.e. user-data always takes precedence)
+// NB: This needs to be kept in sync with ParseMetadata so that it tracks all
+// elements of a CloudConfig which that function can populate.
+func mergeCloudConfig(mdcc, udcc config.CloudConfig) (cc config.CloudConfig) {
+	if mdcc.Hostname != "" {
+		if udcc.Hostname != "" {
+			fmt.Printf("Warning: user-data hostname (%s) overrides metadata hostname (%s)\n", udcc.Hostname, mdcc.Hostname)
+		} else {
+			udcc.Hostname = mdcc.Hostname
+		}
+
+	}
+	for _, key := range mdcc.SSHAuthorizedKeys {
+		udcc.SSHAuthorizedKeys = append(udcc.SSHAuthorizedKeys, key)
+	}
+	if mdcc.NetworkConfigPath != "" {
+		if udcc.NetworkConfigPath != "" {
+			fmt.Printf("Warning: user-data NetworkConfigPath %s overrides metadata NetworkConfigPath %s\n", udcc.NetworkConfigPath, mdcc.NetworkConfigPath)
+		} else {
+			udcc.NetworkConfigPath = mdcc.NetworkConfigPath
+		}
+	}
+	if mdcc.NetworkConfig != "" {
+		if udcc.NetworkConfig != "" {
+			fmt.Printf("Warning: user-data NetworkConfig %s overrides metadata NetworkConfig %s\n", udcc.NetworkConfig, mdcc.NetworkConfig)
+		} else {
+			udcc.NetworkConfig = mdcc.NetworkConfig
+		}
+	}
+	return udcc
+}
+
+// getDatasources creates a slice of possible Datasources for cloudinit based
+// on the different source command-line flags.
+func getDatasources() []datasource.Datasource {
+	dss := make([]datasource.Datasource, 0, 5)
+	if flags.sources.file != "" {
+		dss = append(dss, file.NewDatasource(flags.sources.file))
+	}
+	if flags.sources.url != "" {
+		dss = append(dss, url.NewDatasource(flags.sources.url))
+	}
+	if flags.sources.configDrive != "" {
+		dss = append(dss, configdrive.NewDatasource(flags.sources.configDrive))
+	}
+	if flags.sources.metadataService {
+		dss = append(dss, ec2.NewDatasource(ec2.DefaultAddress))
+	}
+	if flags.sources.ec2MetadataService != "" {
+		dss = append(dss, ec2.NewDatasource(flags.sources.ec2MetadataService))
+	}
+	if flags.sources.cloudSigmaMetadataService {
+		dss = append(dss, cloudsigma.NewServerContextService())
+	}
+	if flags.sources.digitalOceanMetadataService != "" {
+		dss = append(dss, digitalocean.NewDatasource(flags.sources.digitalOceanMetadataService))
+	}
+	if flags.sources.procCmdLine {
+		dss = append(dss, proc_cmdline.NewDatasource())
+	}
+	return dss
+}
+
+// selectDatasource attempts to choose a valid Datasource to use based on its
+// current availability. The first Datasource to report to be available is
+// returned. Datasources will be retried if possible if they are not
+// immediately available. If all Datasources are permanently unavailable or
+// datasourceTimeout is reached before one becomes available, nil is returned.
+func selectDatasource(sources []datasource.Datasource) datasource.Datasource {
+	ds := make(chan datasource.Datasource)
+	stop := make(chan struct{})
+	var wg sync.WaitGroup
+
+	for _, s := range sources {
+		wg.Add(1)
+		go func(s datasource.Datasource) {
+			defer wg.Done()
+
+			duration := datasourceInterval
+			for {
+				fmt.Printf("Checking availability of %q\n", s.Type())
+				if s.IsAvailable() {
+					ds <- s
+					return
+				} else if !s.AvailabilityChanges() {
+					return
+				}
+				select {
+				case <-stop:
+					return
+				case <-time.After(duration):
+					duration = pkg.ExpBackoff(duration, datasourceMaxInterval)
+				}
+			}
+		}(s)
+	}
+
+	done := make(chan struct{})
+	go func() {
+		wg.Wait()
+		close(done)
+	}()
+
+	var s datasource.Datasource
+	select {
+	case s = <-ds:
+	case <-done:
+	case <-time.After(datasourceTimeout):
+	}
+
+	close(stop)
+	return s
+}
+
+// TODO(jonboulle): this should probably be refactored and moved into a different module
+func runScript(script system.Script, env *initialize.Environment) error {
+	err := initialize.PrepWorkspace(env.Workspace())
+	if err != nil {
+		fmt.Printf("Failed preparing workspace: %v\n", err)
+		return err
+	}
+	path, err := initialize.PersistScriptInWorkspace(script, env.Workspace())
 	if err == nil {
 		var name string
 		name, err = system.ExecuteScript(path)
-			initialize.PersistUnitNameInWorkspace(name, workspace)
-		}
-	}
-
-	if err != nil {
-		log.Fatalf("Failed resolving user-data: %v", err)
+		initialize.PersistUnitNameInWorkspace(name, env.Workspace())
 	}
+	return err
 }
--- a/coreos-cloudinit_test.go
+++ b/coreos-cloudinit_test.go
@@ -0,0 +1,120 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+func TestMergeCloudConfig(t *testing.T) {
+	simplecc := config.CloudConfig{
+		SSHAuthorizedKeys: []string{"abc", "def"},
+		Hostname:          "foobar",
+		NetworkConfigPath: "/path/somewhere",
+		NetworkConfig:     `{}`,
+	}
+	for i, tt := range []struct {
+		udcc config.CloudConfig
+		mdcc config.CloudConfig
+		want config.CloudConfig
+	}{
+		{
+			// If mdcc is empty, udcc should be returned unchanged
+			simplecc,
+			config.CloudConfig{},
+			simplecc,
+		},
+		{
+			// If udcc is empty, mdcc should be returned unchanged(overridden)
+			config.CloudConfig{},
+			simplecc,
+			simplecc,
+		},
+		{
+			// user-data should override completely in the case of conflicts
+			simplecc,
+			config.CloudConfig{
+				Hostname:          "meta-hostname",
+				NetworkConfigPath: "/path/meta",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+			simplecc,
+		},
+		{
+			// Mixed merge should succeed
+			config.CloudConfig{
+				SSHAuthorizedKeys: []string{"abc", "def"},
+				Hostname:          "user-hostname",
+				NetworkConfigPath: "/path/somewhere",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+			config.CloudConfig{
+				SSHAuthorizedKeys: []string{"woof", "qux"},
+				Hostname:          "meta-hostname",
+			},
+			config.CloudConfig{
+				SSHAuthorizedKeys: []string{"abc", "def", "woof", "qux"},
+				Hostname:          "user-hostname",
+				NetworkConfigPath: "/path/somewhere",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+		},
+		{
+			// Completely non-conflicting merge should be fine
+			config.CloudConfig{
+				Hostname: "supercool",
+			},
+			config.CloudConfig{
+				SSHAuthorizedKeys: []string{"zaphod", "beeblebrox"},
+				NetworkConfigPath: "/dev/fun",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+			config.CloudConfig{
+				Hostname:          "supercool",
+				SSHAuthorizedKeys: []string{"zaphod", "beeblebrox"},
+				NetworkConfigPath: "/dev/fun",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+		},
+		{
+			// Non-mergeable settings in user-data should not be affected
+			config.CloudConfig{
+				Hostname:       "mememe",
+				ManageEtcHosts: config.EtcHosts("lolz"),
+			},
+			config.CloudConfig{
+				Hostname:          "youyouyou",
+				NetworkConfigPath: "meta-meta-yo",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+			config.CloudConfig{
+				Hostname:          "mememe",
+				ManageEtcHosts:    config.EtcHosts("lolz"),
+				NetworkConfigPath: "meta-meta-yo",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+		},
+		{
+			// Non-mergeable (unexpected) settings in meta-data are ignored
+			config.CloudConfig{
+				Hostname: "mememe",
+			},
+			config.CloudConfig{
+				ManageEtcHosts:    config.EtcHosts("lolz"),
+				NetworkConfigPath: "meta-meta-yo",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+			config.CloudConfig{
+				Hostname:          "mememe",
+				NetworkConfigPath: "meta-meta-yo",
+				NetworkConfig:     `{"hostname":"test"}`,
+			},
+		},
+	} {
+		got := mergeCloudConfig(tt.mdcc, tt.udcc)
+		if !reflect.DeepEqual(got, tt.want) {
+			t.Errorf("case #%d: mergeCloudConfig mutated CloudConfig unexpectedly:\ngot:\n%s\nwant:\n%s", i, got, tt.want)
+		}
+	}
+}
--- a/27
+++ b/27
@@ -0,0 +1,27 @@
+#!/bin/bash -e
+#
+# Generate coverage HTML for a package
+# e.g. PKG=./initialize ./cover
+#
+
+if [ -z "$PKG" ]; then
+	echo "cover only works with a single package, sorry"
+	exit 255
+fi
+
+COVEROUT="coverage"
+
+if ! [ -d "$COVEROUT" ]; then
+	mkdir "$COVEROUT"
+fi
+
+# strip out slashes and dots
+COVERPKG=${PKG//\//}
+COVERPKG=${COVERPKG//./}
+
+# generate arg for "go test"
+export COVER="-coverprofile ${COVEROUT}/${COVERPKG}.out"
+
+source ./test
+
+go tool cover -html=${COVEROUT}/${COVERPKG}.out
--- a/datasource/configdrive/configdrive.go
+++ b/datasource/configdrive/configdrive.go
@@ -0,0 +1,70 @@
+package configdrive
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+)
+
+const (
+	openstackApiVersion = "latest"
+)
+
+type configDrive struct {
+	root     string
+	readFile func(filename string) ([]byte, error)
+}
+
+func NewDatasource(root string) *configDrive {
+	return &configDrive{root, ioutil.ReadFile}
+}
+
+func (cd *configDrive) IsAvailable() bool {
+	_, err := os.Stat(cd.root)
+	return !os.IsNotExist(err)
+}
+
+func (cd *configDrive) AvailabilityChanges() bool {
+	return true
+}
+
+func (cd *configDrive) ConfigRoot() string {
+	return cd.openstackRoot()
+}
+
+func (cd *configDrive) FetchMetadata() ([]byte, error) {
+	return cd.tryReadFile(path.Join(cd.openstackVersionRoot(), "meta_data.json"))
+}
+
+func (cd *configDrive) FetchUserdata() ([]byte, error) {
+	return cd.tryReadFile(path.Join(cd.openstackVersionRoot(), "user_data"))
+}
+
+func (cd *configDrive) FetchNetworkConfig(filename string) ([]byte, error) {
+	if filename == "" {
+		return []byte{}, nil
+	}
+	return cd.tryReadFile(path.Join(cd.openstackRoot(), filename))
+}
+
+func (cd *configDrive) Type() string {
+	return "cloud-drive"
+}
+
+func (cd *configDrive) openstackRoot() string {
+	return path.Join(cd.root, "openstack")
+}
+
+func (cd *configDrive) openstackVersionRoot() string {
+	return path.Join(cd.openstackRoot(), openstackApiVersion)
+}
+
+func (cd *configDrive) tryReadFile(filename string) ([]byte, error) {
+	fmt.Printf("Attempting to read from %q\n", filename)
+	data, err := cd.readFile(filename)
+	if os.IsNotExist(err) {
+		err = nil
+	}
+	return data, err
+}
--- a/datasource/configdrive/configdrive_test.go
+++ b/datasource/configdrive/configdrive_test.go
@@ -0,0 +1,125 @@
+package configdrive
+
+import (
+	"os"
+	"testing"
+)
+
+type mockFilesystem []string
+
+func (m mockFilesystem) readFile(filename string) ([]byte, error) {
+	for _, file := range m {
+		if file == filename {
+			return []byte(filename), nil
+		}
+	}
+	return nil, os.ErrNotExist
+}
+
+func TestFetchMetadata(t *testing.T) {
+	for _, tt := range []struct {
+		root     string
+		filename string
+		files    mockFilesystem
+	}{
+		{
+			"/",
+			"",
+			mockFilesystem{},
+		},
+		{
+			"/",
+			"/openstack/latest/meta_data.json",
+			mockFilesystem([]string{"/openstack/latest/meta_data.json"}),
+		},
+		{
+			"/media/configdrive",
+			"/media/configdrive/openstack/latest/meta_data.json",
+			mockFilesystem([]string{"/media/configdrive/openstack/latest/meta_data.json"}),
+		},
+	} {
+		cd := configDrive{tt.root, tt.files.readFile}
+		filename, err := cd.FetchMetadata()
+		if err != nil {
+			t.Fatalf("bad error for %q: want %q, got %q", tt, nil, err)
+		}
+		if string(filename) != tt.filename {
+			t.Fatalf("bad path for %q: want %q, got %q", tt, tt.filename, filename)
+		}
+	}
+}
+
+func TestFetchUserdata(t *testing.T) {
+	for _, tt := range []struct {
+		root     string
+		filename string
+		files    mockFilesystem
+	}{
+		{
+			"/",
+			"",
+			mockFilesystem{},
+		},
+		{
+			"/",
+			"/openstack/latest/user_data",
+			mockFilesystem([]string{"/openstack/latest/user_data"}),
+		},
+		{
+			"/media/configdrive",
+			"/media/configdrive/openstack/latest/user_data",
+			mockFilesystem([]string{"/media/configdrive/openstack/latest/user_data"}),
+		},
+	} {
+		cd := configDrive{tt.root, tt.files.readFile}
+		filename, err := cd.FetchUserdata()
+		if err != nil {
+			t.Fatalf("bad error for %q: want %q, got %q", tt, nil, err)
+		}
+		if string(filename) != tt.filename {
+			t.Fatalf("bad path for %q: want %q, got %q", tt, tt.filename, filename)
+		}
+	}
+}
+
+func TestConfigRoot(t *testing.T) {
+	for _, tt := range []struct {
+		root       string
+		configRoot string
+	}{
+		{
+			"/",
+			"/openstack",
+		},
+		{
+			"/media/configdrive",
+			"/media/configdrive/openstack",
+		},
+	} {
+		cd := configDrive{tt.root, nil}
+		if configRoot := cd.ConfigRoot(); configRoot != tt.configRoot {
+			t.Fatalf("bad config root for %q: want %q, got %q", tt, tt.configRoot, configRoot)
+		}
+	}
+}
+
+func TestNewDatasource(t *testing.T) {
+	for _, tt := range []struct {
+		root       string
+		expectRoot string
+	}{
+		{
+			root:       "",
+			expectRoot: "",
+		},
+		{
+			root:       "/media/configdrive",
+			expectRoot: "/media/configdrive",
+		},
+	} {
+		service := NewDatasource(tt.root)
+		if service.root != tt.expectRoot {
+			t.Fatalf("bad root (%q): want %q, got %q", tt.root, tt.expectRoot, service.root)
+		}
+	}
+}
--- a/datasource/datasource.go
+++ b/datasource/datasource.go
@@ -1,31 +1,11 @@
 package datasource

-import (
-	"io/ioutil"
-	"net/http"
-)
-
 type Datasource interface {
-	Fetch() ([]byte, error)
+	IsAvailable() bool
+	AvailabilityChanges() bool
+	ConfigRoot() string
+	FetchMetadata() ([]byte, error)
+	FetchUserdata() ([]byte, error)
+	FetchNetworkConfig(string) ([]byte, error)
 	Type() string
 }
-
-func fetchURL(url string) ([]byte, error) {
-	client := http.Client{}
-	resp, err := client.Get(url)
-	if err != nil {
-		return []byte{}, err
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode / 100 != 2 {
-		return []byte{}, nil
-	}
-
-	respBytes, err := ioutil.ReadAll(resp.Body)
-	if err != nil {
-		return nil, err
-	}
-
-	return respBytes, nil
-}
--- a/datasource/file.go
+++ b/datasource/file.go
@@ -1,21 +0,0 @@
-package datasource
-
-import (
-	"io/ioutil"
-)
-
-type localFile struct {
-	path string
-}
-
-func NewLocalFile(path string) *localFile {
-	return &localFile{path}
-}
-
-func (self *localFile) Fetch() ([]byte, error) {
-	return ioutil.ReadFile(self.path)
-}
-
-func (self *localFile) Type() string {
-	return "local-file"
-}
--- a/datasource/file/file.go
+++ b/datasource/file/file.go
@@ -0,0 +1,43 @@
+package file
+
+import (
+	"io/ioutil"
+	"os"
+)
+
+type localFile struct {
+	path string
+}
+
+func NewDatasource(path string) *localFile {
+	return &localFile{path}
+}
+
+func (f *localFile) IsAvailable() bool {
+	_, err := os.Stat(f.path)
+	return !os.IsNotExist(err)
+}
+
+func (f *localFile) AvailabilityChanges() bool {
+	return true
+}
+
+func (f *localFile) ConfigRoot() string {
+	return ""
+}
+
+func (f *localFile) FetchMetadata() ([]byte, error) {
+	return []byte{}, nil
+}
+
+func (f *localFile) FetchUserdata() ([]byte, error) {
+	return ioutil.ReadFile(f.path)
+}
+
+func (f *localFile) FetchNetworkConfig(filename string) ([]byte, error) {
+	return nil, nil
+}
+
+func (f *localFile) Type() string {
+	return "local-file"
+}
--- a/datasource/metadata/cloudsigma/server_context.go
+++ b/datasource/metadata/cloudsigma/server_context.go
@@ -0,0 +1,145 @@
+package cloudsigma
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"os"
+	"strings"
+
+	"github.com/coreos/coreos-cloudinit/third_party/github.com/cloudsigma/cepgo"
+)
+
+const (
+	userDataFieldName = "cloudinit-user-data"
+)
+
+type serverContextService struct {
+	client interface {
+		All() (interface{}, error)
+		Key(string) (interface{}, error)
+		Meta() (map[string]string, error)
+		FetchRaw(string) ([]byte, error)
+	}
+}
+
+func NewServerContextService() *serverContextService {
+	return &serverContextService{
+		client: cepgo.NewCepgo(),
+	}
+}
+
+func (_ *serverContextService) IsAvailable() bool {
+	productNameFile, err := os.Open("/sys/class/dmi/id/product_name")
+	if err != nil {
+		return false
+	}
+	productName := make([]byte, 10)
+	_, err = productNameFile.Read(productName)
+	return err == nil && string(productName) == "CloudSigma"
+}
+
+func (_ *serverContextService) AvailabilityChanges() bool {
+	return true
+}
+
+func (_ *serverContextService) ConfigRoot() string {
+	return ""
+}
+
+func (_ *serverContextService) Type() string {
+	return "server-context"
+}
+
+func (scs *serverContextService) FetchMetadata() ([]byte, error) {
+	var (
+		inputMetadata struct {
+			Name string            `json:"name"`
+			UUID string            `json:"uuid"`
+			Meta map[string]string `json:"meta"`
+			Nics []struct {
+				Runtime struct {
+					InterfaceType string `json:"interface_type"`
+					IPv4          struct {
+						IP string `json:"uuid"`
+					} `json:"ip_v4"`
+				} `json:"runtime"`
+			} `json:"nics"`
+		}
+		outputMetadata struct {
+			Hostname   string            `json:"name"`
+			PublicKeys map[string]string `json:"public_keys"`
+			LocalIPv4  string            `json:"local-ipv4"`
+			PublicIPv4 string            `json:"public-ipv4"`
+		}
+	)
+
+	rawMetadata, err := scs.client.FetchRaw("")
+	if err != nil {
+		return []byte{}, err
+	}
+
+	err = json.Unmarshal(rawMetadata, &inputMetadata)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	if inputMetadata.Name != "" {
+		outputMetadata.Hostname = inputMetadata.Name
+	} else {
+		outputMetadata.Hostname = inputMetadata.UUID
+	}
+
+	if key, ok := inputMetadata.Meta["ssh_public_key"]; ok {
+		splitted := strings.Split(key, " ")
+		outputMetadata.PublicKeys = make(map[string]string)
+		outputMetadata.PublicKeys[splitted[len(splitted)-1]] = key
+	}
+
+	for _, nic := range inputMetadata.Nics {
+		if nic.Runtime.IPv4.IP != "" {
+			if nic.Runtime.InterfaceType == "public" {
+				outputMetadata.PublicIPv4 = nic.Runtime.IPv4.IP
+			} else {
+				outputMetadata.LocalIPv4 = nic.Runtime.IPv4.IP
+			}
+		}
+	}
+
+	return json.Marshal(outputMetadata)
+}
+
+func (scs *serverContextService) FetchUserdata() ([]byte, error) {
+	metadata, err := scs.client.Meta()
+	if err != nil {
+		return []byte{}, err
+	}
+
+	userData, ok := metadata[userDataFieldName]
+	if ok && isBase64Encoded(userDataFieldName, metadata) {
+		if decodedUserData, err := base64.StdEncoding.DecodeString(userData); err == nil {
+			return decodedUserData, nil
+		} else {
+			return []byte{}, nil
+		}
+	}
+
+	return []byte(userData), nil
+}
+
+func (scs *serverContextService) FetchNetworkConfig(a string) ([]byte, error) {
+	return nil, nil
+}
+
+func isBase64Encoded(field string, userdata map[string]string) bool {
+	base64Fields, ok := userdata["base64_fields"]
+	if !ok {
+		return false
+	}
+
+	for _, base64Field := range strings.Split(base64Fields, ",") {
+		if field == base64Field {
+			return true
+		}
+	}
+	return false
+}
--- a/datasource/metadata/cloudsigma/server_context_test.go
+++ b/datasource/metadata/cloudsigma/server_context_test.go
@@ -0,0 +1,152 @@
+package cloudsigma
+
+import (
+	"encoding/json"
+	"reflect"
+	"testing"
+)
+
+type fakeCepgoClient struct {
+	raw  []byte
+	meta map[string]string
+	keys map[string]interface{}
+	err  error
+}
+
+func (f *fakeCepgoClient) All() (interface{}, error) {
+	return f.keys, f.err
+}
+
+func (f *fakeCepgoClient) Key(key string) (interface{}, error) {
+	return f.keys[key], f.err
+}
+
+func (f *fakeCepgoClient) Meta() (map[string]string, error) {
+	return f.meta, f.err
+}
+
+func (f *fakeCepgoClient) FetchRaw(key string) ([]byte, error) {
+	return f.raw, f.err
+}
+
+func TestServerContextFetchMetadata(t *testing.T) {
+	var metadata struct {
+		Hostname   string            `json:"name"`
+		PublicKeys map[string]string `json:"public_keys"`
+		LocalIPv4  string            `json:"local-ipv4"`
+		PublicIPv4 string            `json:"public-ipv4"`
+	}
+	client := new(fakeCepgoClient)
+	scs := NewServerContextService()
+	scs.client = client
+	client.raw = []byte(`{
+		"context": true,
+		"cpu": 4000,
+		"cpu_model": null,
+		"cpus_instead_of_cores": false,
+		"enable_numa": false,
+		"grantees": [],
+		"hv_relaxed": false,
+		"hv_tsc": false,
+		"jobs": [],
+		"mem": 4294967296,
+		"meta": {
+			"base64_fields": "cloudinit-user-data",
+			"cloudinit-user-data": "I2Nsb3VkLWNvbmZpZwoKaG9zdG5hbWU6IGNvcmVvczE=",
+			"ssh_public_key": "ssh-rsa AAAAB3NzaC1yc2E.../hQ5D5 john@doe"
+		},
+		"name": "coreos",
+		"nics": [
+			{
+				"runtime": {
+					"interface_type": "public",
+					"ip_v4": {
+						"uuid": "31.171.251.74"
+					},
+					"ip_v6": null
+				},
+				"vlan": null
+			}
+		],
+		"smp": 2,
+		"status": "running",
+		"uuid": "20a0059b-041e-4d0c-bcc6-9b2852de48b3"
+	}`)
+
+	metadataBytes, err := scs.FetchMetadata()
+	if err != nil {
+		t.Error(err.Error())
+	}
+
+	if err := json.Unmarshal(metadataBytes, &metadata); err != nil {
+		t.Error(err.Error())
+	}
+
+	if metadata.Hostname != "coreos" {
+		t.Errorf("Hostname is not 'coreos' but %s instead", metadata.Hostname)
+	}
+
+	if metadata.PublicKeys["john@doe"] != "ssh-rsa AAAAB3NzaC1yc2E.../hQ5D5 john@doe" {
+		t.Error("Public SSH Keys are not being read properly")
+	}
+
+	if metadata.LocalIPv4 != "" {
+		t.Errorf("Local IP is not empty but %s instead", metadata.LocalIPv4)
+	}
+
+	if metadata.PublicIPv4 != "31.171.251.74" {
+		t.Errorf("Local IP is not 31.171.251.74 but %s instead", metadata.PublicIPv4)
+	}
+}
+
+func TestServerContextFetchUserdata(t *testing.T) {
+	client := new(fakeCepgoClient)
+	scs := NewServerContextService()
+	scs.client = client
+	userdataSets := []struct {
+		in  map[string]string
+		err bool
+		out []byte
+	}{
+		{map[string]string{
+			"base64_fields":       "cloudinit-user-data",
+			"cloudinit-user-data": "aG9zdG5hbWU6IGNvcmVvc190ZXN0",
+		}, false, []byte("hostname: coreos_test")},
+		{map[string]string{
+			"cloudinit-user-data": "#cloud-config\\nhostname: coreos1",
+		}, false, []byte("#cloud-config\\nhostname: coreos1")},
+		{map[string]string{}, false, []byte{}},
+	}
+
+	for i, set := range userdataSets {
+		client.meta = set.in
+		got, err := scs.FetchUserdata()
+		if (err != nil) != set.err {
+			t.Errorf("case %d: bad error state (got %t, want %t)", i, err != nil, set.err)
+		}
+
+		if !reflect.DeepEqual(got, set.out) {
+			t.Errorf("case %d: got %s, want %s", i, got, set.out)
+		}
+	}
+}
+
+func TestServerContextDecodingBase64UserData(t *testing.T) {
+	base64Sets := []struct {
+		in  string
+		out bool
+	}{
+		{"cloudinit-user-data,foo,bar", true},
+		{"bar,cloudinit-user-data,foo,bar", true},
+		{"cloudinit-user-data", true},
+		{"", false},
+		{"foo", false},
+	}
+
+	for _, set := range base64Sets {
+		userdata := map[string]string{"base64_fields": set.in}
+		if isBase64Encoded("cloudinit-user-data", userdata) != set.out {
+			t.Errorf("isBase64Encoded(cloudinit-user-data, %s) should be %t", userdata, set.out)
+		}
+	}
+}
--- a/datasource/metadata/digitalocean/metadata.go
+++ b/datasource/metadata/digitalocean/metadata.go
@@ -0,0 +1,107 @@
+package digitalocean
+
+import (
+	"encoding/json"
+	"strconv"
+
+	"github.com/coreos/coreos-cloudinit/datasource/metadata"
+)
+
+const (
+	DefaultAddress = "http://169.254.169.254/"
+	apiVersion     = "metadata/v1"
+	userdataUrl    = apiVersion + "/user-data"
+	metadataPath   = apiVersion + ".json"
+)
+
+type Address struct {
+	IPAddress string `json:"ip_address"`
+	Netmask   string `json:"netmask"`
+	Cidr      int    `json:"cidr"`
+	Gateway   string `json:"gateway"`
+}
+
+type Interface struct {
+	IPv4 *Address `json:"ipv4"`
+	IPv6 *Address `json:"ipv6"`
+	MAC  string   `json:"mac"`
+	Type string   `json:"type"`
+}
+
+type Interfaces struct {
+	Public  []Interface `json:"public"`
+	Private []Interface `json:"private"`
+}
+
+type DNS struct {
+	Nameservers []string `json:"nameservers"`
+}
+
+type Metadata struct {
+	Hostname   string     `json:"hostname"`
+	Interfaces Interfaces `json:"interfaces"`
+	PublicKeys []string   `json:"public_keys"`
+	DNS        DNS        `json:"dns"`
+}
+
+type metadataService struct {
+	interfaces Interfaces
+	dns        DNS
+	metadata.MetadataService
+}
+
+func NewDatasource(root string) *metadataService {
+	return &metadataService{MetadataService: metadata.NewDatasource(root, apiVersion, userdataUrl, metadataPath)}
+}
+
+func (ms *metadataService) FetchMetadata() ([]byte, error) {
+	data, err := ms.FetchData(ms.MetadataUrl())
+	if err != nil || len(data) == 0 {
+		return []byte{}, err
+	}
+
+	var metadata Metadata
+	if err := json.Unmarshal(data, &metadata); err != nil {
+		return []byte{}, err
+	}
+
+	ms.interfaces = metadata.Interfaces
+	ms.dns = metadata.DNS
+
+	attrs := make(map[string]interface{})
+	if len(metadata.Interfaces.Public) > 0 {
+		if metadata.Interfaces.Public[0].IPv4 != nil {
+			attrs["public-ipv4"] = metadata.Interfaces.Public[0].IPv4.IPAddress
+		}
+		if metadata.Interfaces.Public[0].IPv6 != nil {
+			attrs["public-ipv6"] = metadata.Interfaces.Public[0].IPv6.IPAddress
+		}
+	}
+	if len(metadata.Interfaces.Private) > 0 {
+		if metadata.Interfaces.Private[0].IPv4 != nil {
+			attrs["local-ipv4"] = metadata.Interfaces.Private[0].IPv4.IPAddress
+		}
+		if metadata.Interfaces.Private[0].IPv6 != nil {
+			attrs["local-ipv6"] = metadata.Interfaces.Private[0].IPv6.IPAddress
+		}
+	}
+	attrs["hostname"] = metadata.Hostname
+	keys := make(map[string]string)
+	for i, key := range metadata.PublicKeys {
+		keys[strconv.Itoa(i)] = key
+	}
+	attrs["public_keys"] = keys
+
+	return json.Marshal(attrs)
+}
+
+func (ms metadataService) FetchNetworkConfig(filename string) ([]byte, error) {
+	return json.Marshal(Metadata{
+		Interfaces: ms.interfaces,
+		DNS:        ms.dns,
+	})
+}
+
+func (ms metadataService) Type() string {
+	return "digitalocean-metadata-service"
+}
--- a/datasource/metadata/digitalocean/metadata_test.go
+++ b/datasource/metadata/digitalocean/metadata_test.go
@@ -0,0 +1,99 @@
+package digitalocean
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/datasource/metadata"
+	"github.com/coreos/coreos-cloudinit/datasource/metadata/test"
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+func TestType(t *testing.T) {
+	want := "digitalocean-metadata-service"
+	if kind := (metadataService{}).Type(); kind != want {
+		t.Fatalf("bad type: want %q, got %q", want, kind)
+	}
+}
+
+func TestFetchMetadata(t *testing.T) {
+	for _, tt := range []struct {
+		root         string
+		metadataPath string
+		resources    map[string]string
+		expect       []byte
+		clientErr    error
+		expectErr    error
+	}{
+		{
+			root:         "/",
+			metadataPath: "v1.json",
+			resources: map[string]string{
+				"/v1.json": "bad",
+			},
+			expectErr: fmt.Errorf("invalid character 'b' looking for beginning of value"),
+		},
+		{
+			root:         "/",
+			metadataPath: "v1.json",
+			resources: map[string]string{
+				"/v1.json": `{
+  "droplet_id": 1,
+  "user_data": "hello",
+  "vendor_data": "hello",
+  "public_keys": [
+    "publickey1",
+    "publickey2"
+  ],
+  "region": "nyc2",
+  "interfaces": {
+    "public": [
+      {
+        "ipv4": {
+          "ip_address": "192.168.1.2",
+          "netmask": "255.255.255.0",
+          "gateway": "192.168.1.1"
+        },
+        "ipv6": {
+          "ip_address": "fe00::",
+          "cidr": 126,
+          "gateway": "fe00::"
+        },
+        "mac": "ab:cd:ef:gh:ij",
+        "type": "public"
+      }
+    ]
+  }
+}`,
+			},
+			expect: []byte(`{"hostname":"","public-ipv4":"192.168.1.2","public-ipv6":"fe00::","public_keys":{"0":"publickey1","1":"publickey2"}}`),
+		},
+		{
+			clientErr: pkg.ErrTimeout{fmt.Errorf("test error")},
+			expectErr: pkg.ErrTimeout{fmt.Errorf("test error")},
+		},
+	} {
+		service := &metadataService{
+			MetadataService: metadata.MetadataService{
+				Root:         tt.root,
+				Client:       &test.HttpClient{tt.resources, tt.clientErr},
+				MetadataPath: tt.metadataPath,
+			},
+		}
+		metadata, err := service.FetchMetadata()
+		if Error(err) != Error(tt.expectErr) {
+			t.Fatalf("bad error (%q): want %q, got %q", tt.resources, tt.expectErr, err)
+		}
+		if !bytes.Equal(metadata, tt.expect) {
+			t.Fatalf("bad fetch (%q): want %q, got %q", tt.resources, tt.expect, metadata)
+		}
+	}
+}
+
+func Error(err error) string {
+	if err != nil {
+		return err.Error()
+	}
+	return ""
+}
--- a/datasource/metadata/ec2/metadata.go
+++ b/datasource/metadata/ec2/metadata.go
@@ -0,0 +1,107 @@
+package ec2
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/coreos/coreos-cloudinit/datasource/metadata"
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+const (
+	DefaultAddress = "http://169.254.169.254/"
+	apiVersion     = "2009-04-04/"
+	userdataPath   = apiVersion + "user-data"
+	metadataPath   = apiVersion + "meta-data"
+)
+
+type metadataService struct {
+	metadata.MetadataService
+}
+
+func NewDatasource(root string) *metadataService {
+	return &metadataService{metadata.NewDatasource(root, apiVersion, userdataPath, metadataPath)}
+}
+
+func (ms metadataService) FetchMetadata() ([]byte, error) {
+	attrs := make(map[string]interface{})
+	if keynames, err := ms.fetchAttributes(fmt.Sprintf("%s/public-keys", ms.MetadataUrl())); err == nil {
+		keyIDs := make(map[string]string)
+		for _, keyname := range keynames {
+			tokens := strings.SplitN(keyname, "=", 2)
+			if len(tokens) != 2 {
+				return nil, fmt.Errorf("malformed public key: %q", keyname)
+			}
+			keyIDs[tokens[1]] = tokens[0]
+		}
+
+		keys := make(map[string]string)
+		for name, id := range keyIDs {
+			sshkey, err := ms.fetchAttribute(fmt.Sprintf("%s/public-keys/%s/openssh-key", ms.MetadataUrl(), id))
+			if err != nil {
+				return nil, err
+			}
+			keys[name] = sshkey
+			fmt.Printf("Found SSH key for %q\n", name)
+		}
+		attrs["public_keys"] = keys
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	if hostname, err := ms.fetchAttribute(fmt.Sprintf("%s/hostname", ms.MetadataUrl())); err == nil {
+		attrs["hostname"] = hostname
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	if localAddr, err := ms.fetchAttribute(fmt.Sprintf("%s/local-ipv4", ms.MetadataUrl())); err == nil {
+		attrs["local-ipv4"] = localAddr
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	if publicAddr, err := ms.fetchAttribute(fmt.Sprintf("%s/public-ipv4", ms.MetadataUrl())); err == nil {
+		attrs["public-ipv4"] = publicAddr
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	if content_path, err := ms.fetchAttribute(fmt.Sprintf("%s/network_config/content_path", ms.MetadataUrl())); err == nil {
+		attrs["network_config"] = map[string]string{
+			"content_path": content_path,
+		}
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	return json.Marshal(attrs)
+}
+
+func (ms metadataService) Type() string {
+	return "ec2-metadata-service"
+}
+
+func (ms metadataService) fetchAttributes(url string) ([]string, error) {
+	resp, err := ms.FetchData(url)
+	if err != nil {
+		return nil, err
+	}
+	scanner := bufio.NewScanner(bytes.NewBuffer(resp))
+	data := make([]string, 0)
+	for scanner.Scan() {
+		data = append(data, scanner.Text())
+	}
+	return data, scanner.Err()
+}
+
+func (ms metadataService) fetchAttribute(url string) (string, error) {
+	if attrs, err := ms.fetchAttributes(url); err == nil && len(attrs) > 0 {
+		return attrs[0], nil
+	} else {
+		return "", err
+	}
+}
--- a/datasource/metadata/ec2/metadata_test.go
+++ b/datasource/metadata/ec2/metadata_test.go
@@ -0,0 +1,185 @@
+package ec2
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/datasource/metadata"
+	"github.com/coreos/coreos-cloudinit/datasource/metadata/test"
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+func TestType(t *testing.T) {
+	want := "ec2-metadata-service"
+	if kind := (metadataService{}).Type(); kind != want {
+		t.Fatalf("bad type: want %q, got %q", want, kind)
+	}
+}
+
+func TestFetchAttributes(t *testing.T) {
+	for _, s := range []struct {
+		resources map[string]string
+		err       error
+		tests     []struct {
+			path string
+			val  []string
+		}
+	}{
+		{
+			resources: map[string]string{
+				"/":      "a\nb\nc/",
+				"/c/":    "d\ne/",
+				"/c/e/":  "f",
+				"/a":     "1",
+				"/b":     "2",
+				"/c/d":   "3",
+				"/c/e/f": "4",
+			},
+			tests: []struct {
+				path string
+				val  []string
+			}{
+				{"/", []string{"a", "b", "c/"}},
+				{"/b", []string{"2"}},
+				{"/c/d", []string{"3"}},
+				{"/c/e/", []string{"f"}},
+			},
+		},
+		{
+			err: fmt.Errorf("test error"),
+			tests: []struct {
+				path string
+				val  []string
+			}{
+				{"", nil},
+			},
+		},
+	} {
+		service := metadataService{metadata.MetadataService{
+			Client: &test.HttpClient{s.resources, s.err},
+		}}
+		for _, tt := range s.tests {
+			attrs, err := service.fetchAttributes(tt.path)
+			if err != s.err {
+				t.Fatalf("bad error for %q (%q): want %q, got %q", tt.path, s.resources, s.err, err)
+			}
+			if !reflect.DeepEqual(attrs, tt.val) {
+				t.Fatalf("bad fetch for %q (%q): want %q, got %q", tt.path, s.resources, tt.val, attrs)
+			}
+		}
+	}
+}
+
+func TestFetchAttribute(t *testing.T) {
+	for _, s := range []struct {
+		resources map[string]string
+		err       error
+		tests     []struct {
+			path string
+			val  string
+		}
+	}{
+		{
+			resources: map[string]string{
+				"/":      "a\nb\nc/",
+				"/c/":    "d\ne/",
+				"/c/e/":  "f",
+				"/a":     "1",
+				"/b":     "2",
+				"/c/d":   "3",
+				"/c/e/f": "4",
+			},
+			tests: []struct {
+				path string
+				val  string
+			}{
+				{"/a", "1"},
+				{"/b", "2"},
+				{"/c/d", "3"},
+				{"/c/e/f", "4"},
+			},
+		},
+		{
+			err: fmt.Errorf("test error"),
+			tests: []struct {
+				path string
+				val  string
+			}{
+				{"", ""},
+			},
+		},
+	} {
+		service := metadataService{metadata.MetadataService{
+			Client: &test.HttpClient{s.resources, s.err},
+		}}
+		for _, tt := range s.tests {
+			attr, err := service.fetchAttribute(tt.path)
+			if err != s.err {
+				t.Fatalf("bad error for %q (%q): want %q, got %q", tt.path, s.resources, s.err, err)
+			}
+			if attr != tt.val {
+				t.Fatalf("bad fetch for %q (%q): want %q, got %q", tt.path, s.resources, tt.val, attr)
+			}
+		}
+	}
+}
+
+func TestFetchMetadata(t *testing.T) {
+	for _, tt := range []struct {
+		root         string
+		metadataPath string
+		resources    map[string]string
+		expect       []byte
+		clientErr    error
+		expectErr    error
+	}{
+		{
+			root:         "/",
+			metadataPath: "2009-04-04/meta-data",
+			resources: map[string]string{
+				"/2009-04-04/meta-data/public-keys": "bad\n",
+			},
+			expectErr: fmt.Errorf("malformed public key: \"bad\""),
+		},
+		{
+			root:         "/",
+			metadataPath: "2009-04-04/meta-data",
+			resources: map[string]string{
+				"/2009-04-04/meta-data/hostname":                    "host",
+				"/2009-04-04/meta-data/local-ipv4":                  "1.2.3.4",
+				"/2009-04-04/meta-data/public-ipv4":                 "5.6.7.8",
+				"/2009-04-04/meta-data/public-keys":                 "0=test1\n",
+				"/2009-04-04/meta-data/public-keys/0":               "openssh-key",
+				"/2009-04-04/meta-data/public-keys/0/openssh-key":   "key",
+				"/2009-04-04/meta-data/network_config/content_path": "path",
+			},
+			expect: []byte(`{"hostname":"host","local-ipv4":"1.2.3.4","network_config":{"content_path":"path"},"public-ipv4":"5.6.7.8","public_keys":{"test1":"key"}}`),
+		},
+		{
+			clientErr: pkg.ErrTimeout{fmt.Errorf("test error")},
+			expectErr: pkg.ErrTimeout{fmt.Errorf("test error")},
+		},
+	} {
+		service := &metadataService{metadata.MetadataService{
+			Root:         tt.root,
+			Client:       &test.HttpClient{tt.resources, tt.clientErr},
+			MetadataPath: tt.metadataPath,
+		}}
+		metadata, err := service.FetchMetadata()
+		if Error(err) != Error(tt.expectErr) {
+			t.Fatalf("bad error (%q): want %q, got %q", tt.resources, tt.expectErr, err)
+		}
+		if !bytes.Equal(metadata, tt.expect) {
+			t.Fatalf("bad fetch (%q): want %q, got %q", tt.resources, tt.expect, metadata)
+		}
+	}
+}
+
+func Error(err error) string {
+	if err != nil {
+		return err.Error()
+	}
+	return ""
+}
--- a/datasource/metadata/metadata.go
+++ b/datasource/metadata/metadata.go
@@ -0,0 +1,61 @@
+package metadata
+
+import (
+	"strings"
+
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+type MetadataService struct {
+	Root         string
+	Client       pkg.Getter
+	ApiVersion   string
+	UserdataPath string
+	MetadataPath string
+}
+
+func NewDatasource(root, apiVersion, userdataPath, metadataPath string) MetadataService {
+	if !strings.HasSuffix(root, "/") {
+		root += "/"
+	}
+	return MetadataService{root, pkg.NewHttpClient(), apiVersion, userdataPath, metadataPath}
+}
+
+func (ms MetadataService) IsAvailable() bool {
+	_, err := ms.Client.Get(ms.Root + ms.ApiVersion)
+	return (err == nil)
+}
+
+func (ms MetadataService) AvailabilityChanges() bool {
+	return true
+}
+
+func (ms MetadataService) ConfigRoot() string {
+	return ms.Root
+}
+
+func (ms MetadataService) FetchUserdata() ([]byte, error) {
+	return ms.FetchData(ms.UserdataUrl())
+}
+
+func (ms MetadataService) FetchNetworkConfig(filename string) ([]byte, error) {
+	return nil, nil
+}
+
+func (ms MetadataService) FetchData(url string) ([]byte, error) {
+	if data, err := ms.Client.GetRetry(url); err == nil {
+		return data, err
+	} else if _, ok := err.(pkg.ErrNotFound); ok {
+		return []byte{}, nil
+	} else {
+		return data, err
+	}
+}
+
+func (ms MetadataService) MetadataUrl() string {
+	return (ms.Root + ms.MetadataPath)
+}
+
+func (ms MetadataService) UserdataUrl() string {
+	return (ms.Root + ms.UserdataPath)
+}
--- a/datasource/metadata/metadata_test.go
+++ b/datasource/metadata/metadata_test.go
@@ -0,0 +1,171 @@
+package metadata
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/datasource/metadata/test"
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+func TestAvailabilityChanges(t *testing.T) {
+	want := true
+	if ac := (MetadataService{}).AvailabilityChanges(); ac != want {
+		t.Fatalf("bad AvailabilityChanges: want %q, got %q", want, ac)
+	}
+}
+
+func TestIsAvailable(t *testing.T) {
+	for _, tt := range []struct {
+		root       string
+		apiVersion string
+		resources  map[string]string
+		expect     bool
+	}{
+		{
+			root:       "/",
+			apiVersion: "2009-04-04",
+			resources: map[string]string{
+				"/2009-04-04": "",
+			},
+			expect: true,
+		},
+		{
+			root:      "/",
+			resources: map[string]string{},
+			expect:    false,
+		},
+	} {
+		service := &MetadataService{
+			Root:       tt.root,
+			Client:     &test.HttpClient{tt.resources, nil},
+			ApiVersion: tt.apiVersion,
+		}
+		if a := service.IsAvailable(); a != tt.expect {
+			t.Fatalf("bad isAvailable (%q): want %q, got %q", tt.resources, tt.expect, a)
+		}
+	}
+}
+
+func TestFetchUserdata(t *testing.T) {
+	for _, tt := range []struct {
+		root         string
+		userdataPath string
+		resources    map[string]string
+		userdata     []byte
+		clientErr    error
+		expectErr    error
+	}{
+		{
+			root:         "/",
+			userdataPath: "2009-04-04/user-data",
+			resources: map[string]string{
+				"/2009-04-04/user-data": "hello",
+			},
+			userdata: []byte("hello"),
+		},
+		{
+			root:      "/",
+			clientErr: pkg.ErrNotFound{fmt.Errorf("test not found error")},
+			userdata:  []byte{},
+		},
+		{
+			root:      "/",
+			clientErr: pkg.ErrTimeout{fmt.Errorf("test timeout error")},
+			expectErr: pkg.ErrTimeout{fmt.Errorf("test timeout error")},
+		},
+	} {
+		service := &MetadataService{
+			Root:         tt.root,
+			Client:       &test.HttpClient{tt.resources, tt.clientErr},
+			UserdataPath: tt.userdataPath,
+		}
+		data, err := service.FetchUserdata()
+		if Error(err) != Error(tt.expectErr) {
+			t.Fatalf("bad error (%q): want %q, got %q", tt.resources, tt.expectErr, err)
+		}
+		if !bytes.Equal(data, tt.userdata) {
+			t.Fatalf("bad userdata (%q): want %q, got %q", tt.resources, tt.userdata, data)
+		}
+	}
+}
+
+func TestUrls(t *testing.T) {
+	for _, tt := range []struct {
+		root         string
+		userdataPath string
+		metadataPath string
+		expectRoot   string
+		userdata     string
+		metadata     string
+	}{
+		{
+			root:         "/",
+			userdataPath: "2009-04-04/user-data",
+			metadataPath: "2009-04-04/meta-data",
+			expectRoot:   "/",
+			userdata:     "/2009-04-04/user-data",
+			metadata:     "/2009-04-04/meta-data",
+		},
+		{
+			root:         "http://169.254.169.254/",
+			userdataPath: "2009-04-04/user-data",
+			metadataPath: "2009-04-04/meta-data",
+			expectRoot:   "http://169.254.169.254/",
+			userdata:     "http://169.254.169.254/2009-04-04/user-data",
+			metadata:     "http://169.254.169.254/2009-04-04/meta-data",
+		},
+	} {
+		service := &MetadataService{
+			Root:         tt.root,
+			UserdataPath: tt.userdataPath,
+			MetadataPath: tt.metadataPath,
+		}
+		if url := service.UserdataUrl(); url != tt.userdata {
+			t.Fatalf("bad url (%q): want %q, got %q", tt.root, tt.userdata, url)
+		}
+		if url := service.MetadataUrl(); url != tt.metadata {
+			t.Fatalf("bad url (%q): want %q, got %q", tt.root, tt.metadata, url)
+		}
+		if url := service.ConfigRoot(); url != tt.expectRoot {
+			t.Fatalf("bad url (%q): want %q, got %q", tt.root, tt.expectRoot, url)
+		}
+	}
+}
+
+func TestNewDatasource(t *testing.T) {
+	for _, tt := range []struct {
+		root       string
+		expectRoot string
+	}{
+		{
+			root:       "",
+			expectRoot: "/",
+		},
+		{
+			root:       "/",
+			expectRoot: "/",
+		},
+		{
+			root:       "http://169.254.169.254",
+			expectRoot: "http://169.254.169.254/",
+		},
+		{
+			root:       "http://169.254.169.254/",
+			expectRoot: "http://169.254.169.254/",
+		},
+	} {
+		service := NewDatasource(tt.root, "", "", "")
+		if service.Root != tt.expectRoot {
+			t.Fatalf("bad root (%q): want %q, got %q", tt.root, tt.expectRoot, service.Root)
+		}
+	}
+}
+
+func Error(err error) string {
+	if err != nil {
+		return err.Error()
+	}
+	return ""
+}
--- a/datasource/metadata/test/test.go
+++ b/datasource/metadata/test/test.go
@@ -0,0 +1,27 @@
+package test
+
+import (
+	"fmt"
+
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+type HttpClient struct {
+	Resources map[string]string
+	Err       error
+}
+
+func (t *HttpClient) GetRetry(url string) ([]byte, error) {
+	if t.Err != nil {
+		return nil, t.Err
+	}
+	if val, ok := t.Resources[url]; ok {
+		return []byte(val), nil
+	} else {
+		return nil, pkg.ErrNotFound{fmt.Errorf("not found: %q", url)}
+	}
+}
+
+func (t *HttpClient) Get(url string) ([]byte, error) {
+	return t.GetRetry(url)
+}
--- a/datasource/metadata_service.go
+++ b/datasource/metadata_service.go
@@ -1,17 +0,0 @@
-package datasource
-
-type metadataService struct {
-	url string
-}
-
-func NewMetadataService(url string) *metadataService {
-	return &metadataService{url}
-}
-
-func (ms *metadataService) Fetch() ([]byte, error) {
-	return fetchURL(ms.url)
-}
-
-func (ms *metadataService) Type() string {
-	return "metadata-service"
-}
--- a/datasource/proc_cmdline.go
+++ b/datasource/proc_cmdline.go
@@ -1,66 +0,0 @@
-package datasource
-
-import (
-	"errors"
-	"io/ioutil"
-	"log"
-	"strings"
-)
-
-const (
-	ProcCmdlineLocation        = "/proc/cmdline"
-	ProcCmdlineCloudConfigFlag = "cloud-config-url"
-)
-
-type procCmdline struct{}
-
-func NewProcCmdline() *procCmdline {
-	return &procCmdline{}
-}
-
-func (self *procCmdline) Fetch() ([]byte, error) {
-	cmdline, err := ioutil.ReadFile(ProcCmdlineLocation)
-	if err != nil {
-		return nil, err
-	}
-
-	url, err := findCloudConfigURL(string(cmdline))
-	if err != nil {
-		return nil, err
-	}
-
-	cfg, err := fetchURL(url)
-	if err != nil {
-		return nil, err
-	}
-
-	return cfg, nil
-}
-
-func (self *procCmdline) Type() string {
-	return "proc-cmdline"
-}
-
-func findCloudConfigURL(input string) (url string, err error) {
-	err = errors.New("cloud-config-url not found")
-	for _, token := range strings.Split(input, " ") {
-		parts := strings.SplitN(token, "=", 2)
-
-		key := parts[0]
-		key = strings.Replace(key, "_", "-", -1)
-
-		if key != "cloud-config-url" {
-			continue
-		}
-
-		if len(parts) != 2 {
-			log.Printf("Found cloud-config-url in /proc/cmdline with no value, ignoring.")
-			continue
-		}
-
-		url = parts[1]
-		err = nil
-	}
-
-	return
-}
--- a/datasource/proc_cmdline/proc_cmdline.go
+++ b/datasource/proc_cmdline/proc_cmdline.go
@@ -0,0 +1,99 @@
+package proc_cmdline
+
+import (
+	"errors"
+	"io/ioutil"
+	"log"
+	"strings"
+
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+const (
+	ProcCmdlineLocation        = "/proc/cmdline"
+	ProcCmdlineCloudConfigFlag = "cloud-config-url"
+)
+
+type procCmdline struct {
+	Location string
+}
+
+func NewDatasource() *procCmdline {
+	return &procCmdline{Location: ProcCmdlineLocation}
+}
+
+func (c *procCmdline) IsAvailable() bool {
+	contents, err := ioutil.ReadFile(c.Location)
+	if err != nil {
+		return false
+	}
+
+	cmdline := strings.TrimSpace(string(contents))
+	_, err = findCloudConfigURL(cmdline)
+	return (err == nil)
+}
+
+func (c *procCmdline) AvailabilityChanges() bool {
+	return false
+}
+
+func (c *procCmdline) ConfigRoot() string {
+	return ""
+}
+
+func (c *procCmdline) FetchMetadata() ([]byte, error) {
+	return []byte{}, nil
+}
+
+func (c *procCmdline) FetchUserdata() ([]byte, error) {
+	contents, err := ioutil.ReadFile(c.Location)
+	if err != nil {
+		return nil, err
+	}
+
+	cmdline := strings.TrimSpace(string(contents))
+	url, err := findCloudConfigURL(cmdline)
+	if err != nil {
+		return nil, err
+	}
+
+	client := pkg.NewHttpClient()
+	cfg, err := client.GetRetry(url)
+	if err != nil {
+		return nil, err
+	}
+
+	return cfg, nil
+}
+
+func (c *procCmdline) FetchNetworkConfig(filename string) ([]byte, error) {
+	return nil, nil
+}
+
+func (c *procCmdline) Type() string {
+	return "proc-cmdline"
+}
+
+func findCloudConfigURL(input string) (url string, err error) {
+	err = errors.New("cloud-config-url not found")
+	for _, token := range strings.Split(input, " ") {
+		parts := strings.SplitN(token, "=", 2)
+
+		key := parts[0]
+		key = strings.Replace(key, "_", "-", -1)
+
+		if key != "cloud-config-url" {
+			continue
+		}
+
+		if len(parts) != 2 {
+			log.Printf("Found cloud-config-url in /proc/cmdline with no value, ignoring.")
+			continue
+		}
+
+		url = parts[1]
+		err = nil
+	}
+
+	return
+}
--- a/datasource/proc_cmdline/proc_cmdline_test.go
+++ b/datasource/proc_cmdline/proc_cmdline_test.go
@@ -0,0 +1,88 @@
+package proc_cmdline
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+)
+
+func TestParseCmdlineCloudConfigFound(t *testing.T) {
+	tests := []struct {
+		input  string
+		expect string
+	}{
+		{
+			"cloud-config-url=example.com",
+			"example.com",
+		},
+		{
+			"cloud_config_url=example.com",
+			"example.com",
+		},
+		{
+			"cloud-config-url cloud-config-url=example.com",
+			"example.com",
+		},
+		{
+			"cloud-config-url= cloud-config-url=example.com",
+			"example.com",
+		},
+		{
+			"cloud-config-url=one.example.com cloud-config-url=two.example.com",
+			"two.example.com",
+		},
+		{
+			"foo=bar cloud-config-url=example.com ping=pong",
+			"example.com",
+		},
+	}
+
+	for i, tt := range tests {
+		output, err := findCloudConfigURL(tt.input)
+		if output != tt.expect {
+			t.Errorf("Test case %d failed: %s != %s", i, output, tt.expect)
+		}
+		if err != nil {
+			t.Errorf("Test case %d produced error: %v", i, err)
+		}
+	}
+}
+
+func TestProcCmdlineAndFetchConfig(t *testing.T) {
+
+	var (
+		ProcCmdlineTmpl    = "foo=bar cloud-config-url=%s/config\n"
+		CloudConfigContent = "#cloud-config\n"
+	)
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == "GET" && r.RequestURI == "/config" {
+			fmt.Fprint(w, CloudConfigContent)
+		}
+	}))
+	defer ts.Close()
+
+	file, err := ioutil.TempFile(os.TempDir(), "test_proc_cmdline")
+	defer os.Remove(file.Name())
+	if err != nil {
+		t.Errorf("Test produced error: %v", err)
+	}
+	_, err = file.Write([]byte(fmt.Sprintf(ProcCmdlineTmpl, ts.URL)))
+	if err != nil {
+		t.Errorf("Test produced error: %v", err)
+	}
+
+	p := NewDatasource()
+	p.Location = file.Name()
+	cfg, err := p.FetchUserdata()
+	if err != nil {
+		t.Errorf("Test produced error: %v", err)
+	}
+
+	if string(cfg) != CloudConfigContent {
+		t.Errorf("Test failed, response body: %s != %s", cfg, CloudConfigContent)
+	}
+}
--- a/datasource/proc_cmdline_test.go
+++ b/datasource/proc_cmdline_test.go
@@ -1,47 +0,0 @@
-package datasource
-
-import (
-	"testing"
-)
-
-func TestParseCmdlineCloudConfigFound(t *testing.T) {
-	tests := []struct {
-		input  string
-		expect string
-	}{
-		{
-			"cloud-config-url=example.com",
-			"example.com",
-		},
-		{
-			"cloud_config_url=example.com",
-			"example.com",
-		},
-		{
-			"cloud-config-url cloud-config-url=example.com",
-			"example.com",
-		},
-		{
-			"cloud-config-url= cloud-config-url=example.com",
-			"example.com",
-		},
-		{
-			"cloud-config-url=one.example.com cloud-config-url=two.example.com",
-			"two.example.com",
-		},
-		{
-			"foo=bar cloud-config-url=example.com ping=pong",
-			"example.com",
-		},
-	}
-
-	for i, tt := range tests {
-		output, err := findCloudConfigURL(tt.input)
-		if output != tt.expect {
-			t.Errorf("Test case %d failed: %s != %s", i, output, tt.expect)
-		}
-		if err != nil {
-			t.Errorf("Test case %d produced error: %v", i, err)
-		}
-	}
-}
--- a/datasource/url/url.go
+++ b/datasource/url/url.go
@@ -0,0 +1,44 @@
+package url
+
+import (
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+type remoteFile struct {
+	url string
+}
+
+func NewDatasource(url string) *remoteFile {
+	return &remoteFile{url}
+}
+
+func (f *remoteFile) IsAvailable() bool {
+	client := pkg.NewHttpClient()
+	_, err := client.Get(f.url)
+	return (err == nil)
+}
+
+func (f *remoteFile) AvailabilityChanges() bool {
+	return true
+}
+
+func (f *remoteFile) ConfigRoot() string {
+	return ""
+}
+
+func (f *remoteFile) FetchMetadata() ([]byte, error) {
+	return []byte{}, nil
+}
+
+func (f *remoteFile) FetchUserdata() ([]byte, error) {
+	client := pkg.NewHttpClient()
+	return client.GetRetry(f.url)
+}
+
+func (f *remoteFile) FetchNetworkConfig(filename string) ([]byte, error) {
+	return nil, nil
+}
+
+func (f *remoteFile) Type() string {
+	return "url"
+}
--- a/initialize/config.go
+++ b/initialize/config.go
@@ -1,48 +1,34 @@
 package initialize

 import (
+	"errors"
 	"fmt"
 	"log"
 	"path"

-	"github.com/coreos/coreos-cloudinit/third_party/launchpad.net/goyaml"
-
+	"github.com/coreos/coreos-cloudinit/config"
+	"github.com/coreos/coreos-cloudinit/network"
 	"github.com/coreos/coreos-cloudinit/system"
 )

-type CloudConfig struct {
-	SSHAuthorizedKeys []string `yaml:"ssh_authorized_keys"`
-	Coreos            struct {
-		Etcd   EtcdEnvironment
-		Update map[string]string
-		Units  []system.Unit
-		OEM    OEMRelease
-	}
-	WriteFiles     []system.File `yaml:"write_files"`
-	Hostname       string
-	Users          []system.User
-	ManageEtcHosts string `yaml:"manage_etc_hosts"`
+// CloudConfigFile represents a CoreOS specific configuration option that can generate
+// an associated system.File to be written to disk
+type CloudConfigFile interface {
+	// File should either return (*system.File, error), or (nil, nil) if nothing
+	// needs to be done for this configuration option.
+	File() (*system.File, error)
 }

-func NewCloudConfig(contents string) (*CloudConfig, error) {
-	var cfg CloudConfig
-	err := goyaml.Unmarshal([]byte(contents), &cfg)
-	return &cfg, err
+// CloudConfigUnit represents a CoreOS specific configuration option that can generate
+// associated system.Units to be created/enabled appropriately
+type CloudConfigUnit interface {
+	Units() ([]system.Unit, error)
 }

-func (cc CloudConfig) String() string {
-	bytes, err := goyaml.Marshal(cc)
-	if err != nil {
-		return ""
-	}
-
-	stringified := string(bytes)
-	stringified = fmt.Sprintf("#cloud-config\n%s", stringified)
-
-	return stringified
-}
-
-func Apply(cfg CloudConfig, env *Environment) error {
+// Apply renders a CloudConfig to an Environment. This can involve things like
+// configuring the hostname, adding new users, writing various configuration
+// files to disk, and manipulating systemd services.
+func Apply(cfg config.CloudConfig, env *Environment) error {
 	if cfg.Hostname != "" {
 		if err := system.SetHostname(cfg.Hostname); err != nil {
 			return err
@@ -50,14 +36,6 @@ func Apply(cfg CloudConfig, env *Environment) error {
 		log.Printf("Set hostname to %s", cfg.Hostname)
 	}

-	if cfg.Coreos.OEM.ID != "" {
-		if err := WriteOEMRelease(&cfg.Coreos.OEM, env.Root()); err != nil {
-			return err
-		}
-		log.Printf("Wrote /etc/oem-release to filesystem")
-	}
-
-	if len(cfg.Users) > 0 {
 	for _, user := range cfg.Users {
 		if user.Name == "" {
 			log.Printf("User object has no 'name' field, skipping")
@@ -100,7 +78,6 @@ func Apply(cfg CloudConfig, env *Environment) error {
 			}
 		}
 	}
-	}

 	if len(cfg.SSHAuthorizedKeys) > 0 {
 		err := system.AuthorizeSSHKeys("core", env.SSHKeyName(), cfg.SSHAuthorizedKeys)
@@ -111,47 +88,132 @@ func Apply(cfg CloudConfig, env *Environment) error {
 		}
 	}

-	if len(cfg.WriteFiles) > 0 {
+	var writeFiles []system.File
 	for _, file := range cfg.WriteFiles {
-			file.Path = path.Join(env.Root(), file.Path)
-			if err := system.WriteFile(&file); err != nil {
+		writeFiles = append(writeFiles, system.File{file})
+	}
+
+	for _, ccf := range []CloudConfigFile{
+		system.OEM{cfg.Coreos.OEM},
+		system.Update{cfg.Coreos.Update, system.DefaultReadConfig},
+		system.EtcHosts{cfg.ManageEtcHosts},
+	} {
+		f, err := ccf.File()
+		if err != nil {
 			return err
 		}
-			log.Printf("Wrote file %s to filesystem", file.Path)
+		if f != nil {
+			writeFiles = append(writeFiles, *f)
 		}
 	}

-	if len(cfg.Coreos.Etcd) > 0 {
-		if err := WriteEtcdEnvironment(cfg.Coreos.Etcd, env.Root()); err != nil {
-			log.Fatalf("Failed to write etcd config to filesystem: %v", err)
+	var units []system.Unit
+	for _, u := range cfg.Coreos.Units {
+		units = append(units, system.Unit{u})
 	}

-		log.Printf("Wrote etcd config file to filesystem")
+	for _, ccu := range []CloudConfigUnit{
+		system.Etcd{cfg.Coreos.Etcd},
+		system.Fleet{cfg.Coreos.Fleet},
+		system.Update{cfg.Coreos.Update, system.DefaultReadConfig},
+	} {
+		u, err := ccu.Units()
+		if err != nil {
+			return err
+		}
+		units = append(units, u...)
 	}

-	if s, ok := cfg.Coreos.Update["reboot-strategy"]; ok {
-		if err := WriteLocksmithConfig(s, env.Root()); err != nil {
-			log.Fatalf("Failed to write locksmith config to filesystem: %v", err)
+	wroteEnvironment := false
+	for _, file := range writeFiles {
+		fullPath, err := system.WriteFile(&file, env.Root())
+		if err != nil {
+			return err
 		}
-		log.Printf("Wrote locksmith config file to filesystem")
+		if path.Clean(file.Path) == "/etc/environment" {
+			wroteEnvironment = true
+		}
+		log.Printf("Wrote file %s to filesystem", fullPath)
 	}

-	if len(cfg.Coreos.Units) > 0 {
-		commands := make(map[string]string, 0)
-		for _, unit := range cfg.Coreos.Units {
-			dst := system.UnitDestination(&unit, env.Root())
+	if !wroteEnvironment {
+		ef := env.DefaultEnvironmentFile()
+		if ef != nil {
+			err := system.WriteEnvFile(ef, env.Root())
+			if err != nil {
+				return err
+			}
+			log.Printf("Updated /etc/environment")
+		}
+	}
+
+	if env.NetconfType() != "" {
+		var interfaces []network.InterfaceGenerator
+		var err error
+		switch env.NetconfType() {
+		case "debian":
+			interfaces, err = network.ProcessDebianNetconf(cfg.NetworkConfig)
+		case "digitalocean":
+			interfaces, err = network.ProcessDigitalOceanNetconf(cfg.NetworkConfig)
+		default:
+			return fmt.Errorf("Unsupported network config format %q", env.NetconfType())
+		}
+
+		if err != nil {
+			return err
+		}
+
+		if err := system.WriteNetworkdConfigs(interfaces); err != nil {
+			return err
+		}
+		if err := system.RestartNetwork(interfaces); err != nil {
+			return err
+		}
+	}
+
+	um := system.NewUnitManager(env.Root())
+	return processUnits(units, env.Root(), um)
+
+}
+
+// processUnits takes a set of Units and applies them to the given root using
+// the given UnitManager. This can involve things like writing unit files to
+// disk, masking/unmasking units, or invoking systemd
+// commands against units. It returns any error encountered.
+func processUnits(units []system.Unit, root string, um system.UnitManager) error {
+	type action struct {
+		unit    string
+		command string
+	}
+	actions := make([]action, 0, len(units))
+	reload := false
+	for _, unit := range units {
+		dst := unit.Destination(root)
 		if unit.Content != "" {
 			log.Printf("Writing unit %s to filesystem at path %s", unit.Name, dst)
-				if err := system.PlaceUnit(&unit, dst); err != nil {
+			if err := um.PlaceUnit(&unit, dst); err != nil {
 				return err
 			}
 			log.Printf("Placed unit %s at %s", unit.Name, dst)
+			reload = true
+		}
+
+		if unit.Mask {
+			log.Printf("Masking unit file %s", unit.Name)
+			if err := um.MaskUnit(&unit); err != nil {
+				return err
+			}
+		} else if unit.Runtime {
+			log.Printf("Ensuring runtime unit file %s is unmasked", unit.Name)
+			if err := um.UnmaskUnit(&unit); err != nil {
+				return err
+			}
 		}

 		if unit.Enable {
 			if unit.Group() != "network" {
-					log.Printf("Enabling unit file %s", dst)
-					if err := system.EnableUnitFile(dst, unit.Runtime); err != nil {
+				log.Printf("Enabling unit file %s", unit.Name)
+				if err := um.EnableUnitFile(unit.Name, unit.Runtime); err != nil {
 					return err
 				}
 				log.Printf("Enabled unit %s", unit.Name)
@@ -161,36 +223,25 @@ func Apply(cfg CloudConfig, env *Environment) error {
 		}

 		if unit.Group() == "network" {
-				commands["systemd-networkd.service"] = "restart"
-			} else {
-				if unit.Command != "" {
-					commands[unit.Name] = unit.Command
-				}
+			actions = append(actions, action{"systemd-networkd.service", "restart"})
+		} else if unit.Command != "" {
+			actions = append(actions, action{unit.Name, unit.Command})
 		}
 	}

-		if err := system.DaemonReload(); err != nil {
-			log.Fatalf("Failed systemd daemon-reload: %v", err)
+	if reload {
+		if err := um.DaemonReload(); err != nil {
+			return errors.New(fmt.Sprintf("failed systemd daemon-reload: %v", err))
+		}
 	}

-		for unit, command := range commands {
-			log.Printf("Calling unit command '%s %s'", command, unit)
-			res, err := system.RunUnitCommand(command, unit)
+	for _, action := range actions {
+		log.Printf("Calling unit command '%s %s'", action.command, action.unit)
+		res, err := um.RunUnitCommand(action.command, action.unit)
 		if err != nil {
 			return err
 		}
-			log.Printf("Result of '%s %s': %s", command, unit, res)
-		}
-	}
-
-	if cfg.ManageEtcHosts != "" {
-
-		if err := WriteEtcHosts(cfg.ManageEtcHosts, env.Root()); err != nil {
-			log.Fatalf("Failed to write /etc/hosts to filesystem: %v", err)
-		}
-
-		log.Printf("Wrote /etc/hosts file to filesystem")
-
+		log.Printf("Result of '%s %s': %s", action.command, action.unit, res)
 	}

 	return nil
--- a/initialize/config_test.go
+++ b/initialize/config_test.go
@@ -1,249 +1,114 @@
 package initialize

 import (
-	"strings"
 	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+	"github.com/coreos/coreos-cloudinit/system"
 )

-// Assert that the parsing of a cloud config file "generally works"
-func TestCloudConfigEmpty(t *testing.T) {
-	cfg, err := NewCloudConfig("")
-	if err != nil {
-		t.Fatalf("Encountered unexpected error :%v", err)
-	}
-
-	keys := cfg.SSHAuthorizedKeys
-	if len(keys) != 0 {
-		t.Error("Parsed incorrect number of SSH keys")
-	}
-
-	if len(cfg.WriteFiles) != 0 {
-		t.Error("Expected zero WriteFiles")
-	}
-
-	if cfg.Hostname != "" {
-		t.Errorf("Expected hostname to be empty, got '%s'", cfg.Hostname)
-	}
+type TestUnitManager struct {
+	placed   []string
+	enabled  []string
+	masked   []string
+	unmasked []string
+	commands map[string]string
+	reload   bool
 }

-// Assert that the parsing of a cloud config file "generally works"
-func TestCloudConfig(t *testing.T) {
-	contents := `
-coreos: 
-  etcd:
-    discovery: "https://discovery.etcd.io/827c73219eeb2fa5530027c37bf18877"
-  update:
-    reboot-strategy: reboot
-  units:
-    - name: 50-eth0.network
-      runtime: yes
-      content: '[Match]
- 
-    Name=eth47
- 
- 
-    [Network]
- 
-    Address=10.209.171.177/19
- 
-'
-  oem:
-    id: rackspace
-    name: Rackspace Cloud Servers
-    version-id: 168.0.0
-    home-url: https://www.rackspace.com/cloud/servers/
-    bug-report-url: https://github.com/coreos/coreos-overlay
-ssh_authorized_keys:
-  - foobar
-  - foobaz
-write_files:
-  - content: |
-      penny
-      elroy
-    path: /etc/dogepack.conf
-    permissions: '0644'
-    owner: root:dogepack
-hostname: trontastic
-`
-	cfg, err := NewCloudConfig(contents)
-	if err != nil {
-		t.Fatalf("Encountered unexpected error :%v", err)
-	}
-
-	keys := cfg.SSHAuthorizedKeys
-	if len(keys) != 2 {
-		t.Error("Parsed incorrect number of SSH keys")
-	} else if keys[0] != "foobar" {
-		t.Error("Expected first SSH key to be 'foobar'")
-	} else if keys[1] != "foobaz" {
-		t.Error("Expected first SSH key to be 'foobaz'")
-	}
-
-	if len(cfg.WriteFiles) != 1 {
-		t.Error("Failed to parse correct number of write_files")
-	} else {
-		wf := cfg.WriteFiles[0]
-		if wf.Content != "penny\nelroy\n" {
-			t.Errorf("WriteFile has incorrect contents '%s'", wf.Content)
-		}
-		if wf.Encoding != "" {
-			t.Errorf("WriteFile has incorrect encoding %s", wf.Encoding)
-		}
-		if perm, _ := wf.Permissions(); perm != 0644 {
-			t.Errorf("WriteFile has incorrect permissions %s", perm)
-		}
-		if wf.Path != "/etc/dogepack.conf" {
-			t.Errorf("WriteFile has incorrect path %s", wf.Path)
-		}
-		if wf.Owner != "root:dogepack" {
-			t.Errorf("WriteFile has incorrect owner %s", wf.Owner)
-		}
-	}
-
-	if len(cfg.Coreos.Units) != 1 {
-		t.Error("Failed to parse correct number of units")
-	} else {
-		u := cfg.Coreos.Units[0]
-		expect := `[Match]
-Name=eth47
-
-[Network]
-Address=10.209.171.177/19
-`
-		if u.Content != expect {
-			t.Errorf("Unit has incorrect contents '%s'.\nExpected '%s'.", u.Content, expect)
-		}
-		if u.Runtime != true {
-			t.Errorf("Unit has incorrect runtime value")
-		}
-		if u.Name != "50-eth0.network" {
-			t.Errorf("Unit has incorrect name %s", u.Name)
-		}
-		if u.Type() != "network" {
-			t.Errorf("Unit has incorrect type '%s'", u.Type())
-		}
-	}
-
-	if cfg.Coreos.OEM.ID != "rackspace" {
-		t.Errorf("Failed parsing coreos.oem. Expected ID 'rackspace', got %q.", cfg.Coreos.OEM.ID)
-	}
-
-	if cfg.Hostname != "trontastic" {
-		t.Errorf("Failed to parse hostname")
-	}
-	if cfg.Coreos.Update["reboot-strategy"] != "reboot" {
-		t.Errorf("Failed to parse locksmith strategy")
-	}
+func (tum *TestUnitManager) PlaceUnit(unit *system.Unit, dst string) error {
+	tum.placed = append(tum.placed, unit.Name)
+	return nil
+}
+func (tum *TestUnitManager) EnableUnitFile(unit string, runtime bool) error {
+	tum.enabled = append(tum.enabled, unit)
+	return nil
+}
+func (tum *TestUnitManager) RunUnitCommand(command, unit string) (string, error) {
+	tum.commands = make(map[string]string)
+	tum.commands[unit] = command
+	return "", nil
+}
+func (tum *TestUnitManager) DaemonReload() error {
+	tum.reload = true
+	return nil
+}
+func (tum *TestUnitManager) MaskUnit(unit *system.Unit) error {
+	tum.masked = append(tum.masked, unit.Name)
+	return nil
+}
+func (tum *TestUnitManager) UnmaskUnit(unit *system.Unit) error {
+	tum.unmasked = append(tum.unmasked, unit.Name)
+	return nil
 }

-// Assert that our interface conversion doesn't panic
-func TestCloudConfigKeysNotList(t *testing.T) {
-	contents := `
-ssh_authorized_keys:
-  - foo: bar
-`
-	cfg, err := NewCloudConfig(contents)
-	if err != nil {
-		t.Fatalf("Encountered unexpected error :%v", err)
+func TestProcessUnits(t *testing.T) {
+	tum := &TestUnitManager{}
+	units := []system.Unit{
+		system.Unit{config.Unit{
+			Name: "foo",
+			Mask: true,
+		}},
+	}
+	if err := processUnits(units, "", tum); err != nil {
+		t.Fatalf("unexpected error calling processUnits: %v", err)
+	}
+	if len(tum.masked) != 1 || tum.masked[0] != "foo" {
+		t.Errorf("expected foo to be masked, but found %v", tum.masked)
 	}

-	keys := cfg.SSHAuthorizedKeys
-	if len(keys) != 0 {
-		t.Error("Parsed incorrect number of SSH keys")
-	}
-}
-
-func TestCloudConfigSerializationHeader(t *testing.T) {
-	cfg, _ := NewCloudConfig("")
-	contents := cfg.String()
-	header := strings.SplitN(contents, "\n", 2)[0]
-	if header != "#cloud-config" {
-		t.Fatalf("Serialized config did not have expected header")
-	}
-}
-
-func TestCloudConfigUsers(t *testing.T) {
-	contents := `
-users:
-  - name: elroy
-    passwd: somehash
-    ssh-authorized-keys:
-      - somekey
-    gecos: arbitrary comment
-    homedir: /home/place
-    no-create-home: yes
-    primary-group: things
-    groups:
-      - ping
-      - pong
-    no-user-group: true
-    system: y
-    no-log-init: True
-`
-	cfg, err := NewCloudConfig(contents)
-	if err != nil {
-		t.Fatalf("Encountered unexpected error: %v", err)
-	}
-
-	if len(cfg.Users) != 1 {
-		t.Fatalf("Parsed %d users, expected 1", cfg.Users)
-	}
-
-	user := cfg.Users[0]
-
-	if user.Name != "elroy" {
-		t.Errorf("User name is %q, expected 'elroy'", user.Name)
-	}
-
-	if user.PasswordHash != "somehash" {
-		t.Errorf("User passwd is %q, expected 'somehash'", user.PasswordHash)
-	}
-
-	if keys := user.SSHAuthorizedKeys; len(keys) != 1 {
-		t.Errorf("Parsed %d ssh keys, expected 1", len(keys))
-	} else {
-		key := user.SSHAuthorizedKeys[0]
-		if key != "somekey" {
-			t.Errorf("User SSH key is %q, expected 'somekey'", key)
-		}
-	}
-
-	if user.GECOS != "arbitrary comment" {
-		t.Errorf("Failed to parse gecos field, got %q", user.GECOS)
-	}
-
-	if user.Homedir != "/home/place" {
-		t.Errorf("Failed to parse homedir field, got %q", user.Homedir)
-	}
-
-	if !user.NoCreateHome {
-		t.Errorf("Failed to parse no-create-home field")
-	}
-
-	if user.PrimaryGroup != "things" {
-		t.Errorf("Failed to parse primary-group field, got %q", user.PrimaryGroup)
-	}
-
-	if len(user.Groups) != 2 {
-		t.Errorf("Failed to parse 2 goups, got %d", len(user.Groups))
-	} else {
-		if user.Groups[0] != "ping" {
-			t.Errorf("First group was %q, not expected value 'ping'", user.Groups[0])
-		}
-		if user.Groups[1] != "pong" {
-			t.Errorf("First group was %q, not expected value 'pong'", user.Groups[1])
-		}
-	}
-
-	if !user.NoUserGroup {
-		t.Errorf("Failed to parse no-user-group field")
-	}
-
-	if !user.System {
-		t.Errorf("Failed to parse system field")
-	}
-
-	if !user.NoLogInit {
-		t.Errorf("Failed to parse no-log-init field")
+	tum = &TestUnitManager{}
+	units = []system.Unit{
+		system.Unit{config.Unit{
+			Name: "bar.network",
+		}},
+	}
+	if err := processUnits(units, "", tum); err != nil {
+		t.Fatalf("unexpected error calling processUnits: %v", err)
+	}
+	if _, ok := tum.commands["systemd-networkd.service"]; !ok {
+		t.Errorf("expected systemd-networkd.service to be reloaded!")
+	}
+
+	tum = &TestUnitManager{}
+	units = []system.Unit{
+		system.Unit{config.Unit{
+			Name:    "baz.service",
+			Content: "[Service]\nExecStart=/bin/true",
+		}},
+	}
+	if err := processUnits(units, "", tum); err != nil {
+		t.Fatalf("unexpected error calling processUnits: %v", err)
+	}
+	if len(tum.placed) != 1 || tum.placed[0] != "baz.service" {
+		t.Fatalf("expected baz.service to be written, but got %v", tum.placed)
+	}
+
+	tum = &TestUnitManager{}
+	units = []system.Unit{
+		system.Unit{config.Unit{
+			Name:    "locksmithd.service",
+			Runtime: true,
+		}},
+	}
+	if err := processUnits(units, "", tum); err != nil {
+		t.Fatalf("unexpected error calling processUnits: %v", err)
+	}
+	if len(tum.unmasked) != 1 || tum.unmasked[0] != "locksmithd.service" {
+		t.Fatalf("expected locksmithd.service to be unmasked, but got %v", tum.unmasked)
+	}
+
+	tum = &TestUnitManager{}
+	units = []system.Unit{
+		system.Unit{config.Unit{
+			Name:   "woof",
+			Enable: true,
+		}},
+	}
+	if err := processUnits(units, "", tum); err != nil {
+		t.Fatalf("unexpected error calling processUnits: %v", err)
+	}
+	if len(tum.enabled) != 1 || tum.enabled[0] != "woof" {
+		t.Fatalf("expected woof to be enabled, but got %v", tum.enabled)
 	}
 }
--- a/initialize/env.go
+++ b/initialize/env.go
@@ -3,45 +3,105 @@ package initialize
 import (
 	"os"
 	"path"
+	"regexp"
 	"strings"
+
+	"github.com/coreos/coreos-cloudinit/config"
+	"github.com/coreos/coreos-cloudinit/system"
 )

 const DefaultSSHKeyName = "coreos-cloudinit"

 type Environment struct {
 	root          string
+	configRoot    string
 	workspace     string
+	netconfType   string
 	sshKeyName    string
 	substitutions map[string]string
 }

-func NewEnvironment(root, workspace string) *Environment {
-	substitutions := map[string]string{
+// TODO(jonboulle): this is getting unwieldy, should be able to simplify the interface somehow
+func NewEnvironment(root, configRoot, workspace, netconfType, sshKeyName string, substitutions map[string]string) *Environment {
+	if substitutions == nil {
+		substitutions = make(map[string]string)
+	}
+	// If certain values are not in the supplied substitution, fall back to retrieving them from the environment
+	for k, v := range map[string]string{
 		"$public_ipv4":  os.Getenv("COREOS_PUBLIC_IPV4"),
 		"$private_ipv4": os.Getenv("COREOS_PRIVATE_IPV4"),
+		"$public_ipv6":  os.Getenv("COREOS_PUBLIC_IPV6"),
+		"$private_ipv6": os.Getenv("COREOS_PRIVATE_IPV6"),
+	} {
+		if _, ok := substitutions[k]; !ok {
+			substitutions[k] = v
 		}
-	return &Environment{root, workspace, DefaultSSHKeyName, substitutions}
+	}
+	return &Environment{root, configRoot, workspace, netconfType, sshKeyName, substitutions}
 }

-func (self *Environment) Workspace() string {
-	return path.Join(self.root, self.workspace)
+func (e *Environment) Workspace() string {
+	return path.Join(e.root, e.workspace)
 }

-func (self *Environment) Root() string {
-	return self.root
+func (e *Environment) Root() string {
+	return e.root
 }

-func (self *Environment) SSHKeyName() string {
-	return self.sshKeyName
+func (e *Environment) ConfigRoot() string {
+	return e.configRoot
 }

-func (self *Environment) SetSSHKeyName(name string) {
-	self.sshKeyName = name
+func (e *Environment) NetconfType() string {
+	return e.netconfType
 }

-func (self *Environment) Apply(data string) string {
-	for key, val := range self.substitutions {
-		data = strings.Replace(data, key, val, -1)
+func (e *Environment) SSHKeyName() string {
+	return e.sshKeyName
+}
+
+func (e *Environment) SetSSHKeyName(name string) {
+	e.sshKeyName = name
+}
+
+// Apply goes through the map of substitutions and replaces all instances of
+// the keys with their respective values. It supports escaping substitutions
+// with a leading '\'.
+func (e *Environment) Apply(data string) string {
+	for key, val := range e.substitutions {
+		matchKey := strings.Replace(key, `$`, `\$`, -1)
+		replKey := strings.Replace(key, `$`, `$$`, -1)
+
+		// "key" -> "val"
+		data = regexp.MustCompile(`([^\\]|^)`+matchKey).ReplaceAllString(data, `${1}`+val)
+		// "\key" -> "key"
+		data = regexp.MustCompile(`\\`+matchKey).ReplaceAllString(data, replKey)
 	}
 	return data
 }
+
+func (e *Environment) DefaultEnvironmentFile() *system.EnvFile {
+	ef := system.EnvFile{
+		File: &system.File{config.File{
+			Path: "/etc/environment",
+		}},
+		Vars: map[string]string{},
+	}
+	if ip, ok := e.substitutions["$public_ipv4"]; ok && len(ip) > 0 {
+		ef.Vars["COREOS_PUBLIC_IPV4"] = ip
+	}
+	if ip, ok := e.substitutions["$private_ipv4"]; ok && len(ip) > 0 {
+		ef.Vars["COREOS_PRIVATE_IPV4"] = ip
+	}
+	if ip, ok := e.substitutions["$public_ipv6"]; ok && len(ip) > 0 {
+		ef.Vars["COREOS_PUBLIC_IPV6"] = ip
+	}
+	if ip, ok := e.substitutions["$private_ipv6"]; ok && len(ip) > 0 {
+		ef.Vars["COREOS_PRIVATE_IPV6"] = ip
+	}
+	if len(ef.Vars) == 0 {
+		return nil
+	} else {
+		return &ef
+	}
+}
--- a/initialize/env_test.go
+++ b/initialize/env_test.go
@@ -1,27 +1,132 @@
 package initialize

 import (
+	"io/ioutil"
 	"os"
+	"path"
 	"testing"
+
+	"github.com/coreos/coreos-cloudinit/system"
 )

 func TestEnvironmentApply(t *testing.T) {
-	os.Setenv("COREOS_PUBLIC_IPV4", "192.0.2.3")
-	os.Setenv("COREOS_PRIVATE_IPV4", "192.0.2.203")
-	env := NewEnvironment("./", "./")
-	input := `[Service]
-ExecStart=/usr/bin/echo "$public_ipv4"
-ExecStop=/usr/bin/echo $private_ipv4
-ExecStop=/usr/bin/echo $unknown
-`
-	expected := `[Service]
-ExecStart=/usr/bin/echo "192.0.2.3"
-ExecStop=/usr/bin/echo 192.0.2.203
-ExecStop=/usr/bin/echo $unknown
-`
+	os.Setenv("COREOS_PUBLIC_IPV4", "1.2.3.4")
+	os.Setenv("COREOS_PRIVATE_IPV4", "5.6.7.8")
+	os.Setenv("COREOS_PUBLIC_IPV6", "1234::")
+	os.Setenv("COREOS_PRIVATE_IPV6", "5678::")
+	for _, tt := range []struct {
+		subs  map[string]string
+		input string
+		out   string
+	}{
+		{
+			// Substituting both values directly should always take precedence
+			// over environment variables
+			map[string]string{
+				"$public_ipv4":  "192.0.2.3",
+				"$private_ipv4": "192.0.2.203",
+				"$public_ipv6":  "fe00:1234::",
+				"$private_ipv6": "fe00:5678::",
+			},
+			`[Service]
+ExecStart=/usr/bin/echo "$public_ipv4 $public_ipv6"
+ExecStop=/usr/bin/echo $private_ipv4 $private_ipv6
+ExecStop=/usr/bin/echo $unknown`,
+			`[Service]
+ExecStart=/usr/bin/echo "192.0.2.3 fe00:1234::"
+ExecStop=/usr/bin/echo 192.0.2.203 fe00:5678::
+ExecStop=/usr/bin/echo $unknown`,
+		},
+		{
+			// Substituting one value directly while falling back with the other
+			map[string]string{"$private_ipv4": "127.0.0.1"},
+			"$private_ipv4\n$public_ipv4",
+			"127.0.0.1\n1.2.3.4",
+		},
+		{
+			// Falling back to environment variables for both values
+			map[string]string{"foo": "bar"},
+			"$private_ipv4\n$public_ipv4",
+			"5.6.7.8\n1.2.3.4",
+		},
+		{
+			// No substitutions
+			nil,
+			"$private_ipv4\nfoobar",
+			"5.6.7.8\nfoobar",
+		},
+		{
+			// Escaping substitutions
+			map[string]string{"$private_ipv4": "127.0.0.1"},
+			`\$private_ipv4
+$private_ipv4
+addr: \$private_ipv4
+\\$private_ipv4`,
+			`$private_ipv4
+127.0.0.1
+addr: $private_ipv4
+\$private_ipv4`,
+		},
+		{
+			// No substitutions with escaping
+			nil,
+			"\\$test\n$test",
+			"\\$test\n$test",
+		},
+	} {

-	output := env.Apply(input)
-	if output != expected {
-		t.Fatalf("Environment incorrectly applied.\nOutput:\n%s\nExpected:\n%s", output, expected)
+		env := NewEnvironment("./", "./", "./", "", "", tt.subs)
+		got := env.Apply(tt.input)
+		if got != tt.out {
+			t.Fatalf("Environment incorrectly applied.\ngot:\n%s\nwant:\n%s", got, tt.out)
+		}
+	}
+}
+
+func TestEnvironmentFile(t *testing.T) {
+	subs := map[string]string{
+		"$public_ipv4":  "1.2.3.4",
+		"$private_ipv4": "5.6.7.8",
+		"$public_ipv6":  "1234::",
+		"$private_ipv6": "5678::",
+	}
+	expect := "COREOS_PRIVATE_IPV4=5.6.7.8\nCOREOS_PRIVATE_IPV6=5678::\nCOREOS_PUBLIC_IPV4=1.2.3.4\nCOREOS_PUBLIC_IPV6=1234::\n"
+
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	env := NewEnvironment("./", "./", "./", "", "", subs)
+	ef := env.DefaultEnvironmentFile()
+	err = system.WriteEnvFile(ef, dir)
+	if err != nil {
+		t.Fatalf("WriteEnvFile failed: %v", err)
+	}
+
+	fullPath := path.Join(dir, "etc", "environment")
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != expect {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	}
+}
+
+func TestEnvironmentFileNil(t *testing.T) {
+	subs := map[string]string{
+		"$public_ipv4":  "",
+		"$private_ipv4": "",
+		"$public_ipv6":  "",
+		"$private_ipv6": "",
+	}
+
+	env := NewEnvironment("./", "./", "./", "", "", subs)
+	ef := env.DefaultEnvironmentFile()
+	if ef != nil {
+		t.Fatalf("Environment file not nil: %v", ef)
 	}
 }
--- a/initialize/etcd.go
+++ b/initialize/etcd.go
@@ -1,62 +0,0 @@
-package initialize
-
-import (
-	"errors"
-	"fmt"
-	"path"
-	"strings"
-
-	"github.com/coreos/coreos-cloudinit/system"
-)
-
-type EtcdEnvironment map[string]string
-
-func (ec EtcdEnvironment) normalized() map[string]string {
-	out := make(map[string]string, len(ec))
-	for key, val := range ec {
-		key = strings.ToUpper(key)
-		key = strings.Replace(key, "-", "_", -1)
-		out[key] = val
-	}
-	return out
-}
-
-func (ec EtcdEnvironment) String() (out string) {
-	norm := ec.normalized()
-
-	if val, ok := norm["DISCOVERY_URL"]; ok {
-		delete(norm, "DISCOVERY_URL")
-		if _, ok := norm["DISCOVERY"]; !ok {
-			norm["DISCOVERY"] = val
-		}
-	}
-
-	out += "[Service]\n"
-
-	for key, val := range norm {
-		out += fmt.Sprintf("Environment=\"ETCD_%s=%s\"\n", key, val)
-	}
-
-	return
-}
-
-// Write an EtcdEnvironment to the appropriate path on disk for etcd.service
-func WriteEtcdEnvironment(env EtcdEnvironment, root string) error {
-	if _, ok := env["name"]; !ok {
-		if machineID := system.MachineID(root); machineID != "" {
-			env["name"] = machineID
-		} else if hostname, err := system.Hostname(); err == nil {
-			env["name"] = hostname
-		} else {
-			return errors.New("Unable to determine default etcd name")
-		}
-	}
-
-	file := system.File{
-		Path: path.Join(root, "run", "systemd", "system", "etcd.service.d", "20-cloudinit.conf"),
-		RawFilePermissions: "0644",
-		Content: env.String(),
-	}
-
-	return system.WriteFile(&file)
-}
--- a/initialize/etcd_test.go
+++ b/initialize/etcd_test.go
@@ -1,138 +0,0 @@
-package initialize
-
-import (
-	"io/ioutil"
-	"os"
-	"os/exec"
-	"path"
-	"testing"
-)
-
-func TestEtcdEnvironment(t *testing.T) {
-	cfg := make(EtcdEnvironment, 0)
-	cfg["discovery"] = "http://disco.example.com/foobar"
-	cfg["peer-bind-addr"] = "127.0.0.1:7002"
-
-	env := cfg.String()
-	expect := `[Service]
-Environment="ETCD_DISCOVERY=http://disco.example.com/foobar"
-Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
-`
-
-	if env != expect {
-		t.Errorf("Generated environment:\n%s\nExpected environment:\n%s", env, expect)
-	}
-}
-
-func TestEtcdEnvironmentDiscoveryURLTranslated(t *testing.T) {
-	cfg := make(EtcdEnvironment, 0)
-	cfg["discovery_url"] = "http://disco.example.com/foobar"
-	cfg["peer-bind-addr"] = "127.0.0.1:7002"
-
-	env := cfg.String()
-	expect := `[Service]
-Environment="ETCD_DISCOVERY=http://disco.example.com/foobar"
-Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
-`
-
-	if env != expect {
-		t.Errorf("Generated environment:\n%s\nExpected environment:\n%s", env, expect)
-	}
-}
-
-func TestEtcdEnvironmentDiscoveryOverridesDiscoveryURL(t *testing.T) {
-	cfg := make(EtcdEnvironment, 0)
-	cfg["discovery_url"] = "ping"
-	cfg["discovery"] = "pong"
-	cfg["peer-bind-addr"] = "127.0.0.1:7002"
-
-	env := cfg.String()
-	expect := `[Service]
-Environment="ETCD_DISCOVERY=pong"
-Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
-`
-
-	if env != expect {
-		t.Errorf("Generated environment:\n%s\nExpected environment:\n%s", env, expect)
-	}
-}
-
-func TestEtcdEnvironmentWrittenToDisk(t *testing.T) {
-	ec := EtcdEnvironment{
-		"name":           "node001",
-		"discovery":      "http://disco.example.com/foobar",
-		"peer-bind-addr": "127.0.0.1:7002",
-	}
-	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
-	if err != nil {
-		t.Fatalf("Unable to create tempdir: %v", err)
-	}
-	defer os.RemoveAll(dir)
-
-	if err := WriteEtcdEnvironment(ec, dir); err != nil {
-		t.Fatalf("Processing of EtcdEnvironment failed: %v", err)
-	}
-
-	fullPath := path.Join(dir, "run", "systemd", "system", "etcd.service.d", "20-cloudinit.conf")
-
-	fi, err := os.Stat(fullPath)
-	if err != nil {
-		t.Fatalf("Unable to stat file: %v", err)
-	}
-
-	if fi.Mode() != os.FileMode(0644) {
-		t.Errorf("File has incorrect mode: %v", fi.Mode())
-	}
-
-	contents, err := ioutil.ReadFile(fullPath)
-	if err != nil {
-		t.Fatalf("Unable to read expected file: %v", err)
-	}
-
-	expect := `[Service]
-Environment="ETCD_NAME=node001"
-Environment="ETCD_DISCOVERY=http://disco.example.com/foobar"
-Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
-`
-	if string(contents) != expect {
-		t.Fatalf("File has incorrect contents")
-	}
-}
-
-func TestEtcdEnvironmentWrittenToDiskDefaultToMachineID(t *testing.T) {
-	ec := EtcdEnvironment{}
-	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
-	if err != nil {
-		t.Fatalf("Unable to create tempdir: %v", err)
-	}
-	defer os.RemoveAll(dir)
-
-	os.Mkdir(path.Join(dir, "etc"), os.FileMode(0755))
-	err = ioutil.WriteFile(path.Join(dir, "etc", "machine-id"), []byte("node007"), os.FileMode(0444))
-	if err != nil {
-		t.Fatalf("Failed writing out /etc/machine-id: %v", err)
-	}
-
-	if err := WriteEtcdEnvironment(ec, dir); err != nil {
-		t.Fatalf("Processing of EtcdEnvironment failed: %v", err)
-	}
-
-	fullPath := path.Join(dir, "run", "systemd", "system", "etcd.service.d", "20-cloudinit.conf")
-
-	contents, err := ioutil.ReadFile(fullPath)
-	if err != nil {
-		t.Fatalf("Unable to read expected file: %v", err)
-	}
-
-	expect := `[Service]
-Environment="ETCD_NAME=node007"
-`
-	if string(contents) != expect {
-		t.Fatalf("File has incorrect contents")
-	}
-}
-
-func rmdir(path string) error {
-	cmd := exec.Command("rm", "-rf", path)
-	return cmd.Run()
-}
--- a/initialize/github_test.go
+++ b/initialize/github_test.go
@@ -1,32 +0,0 @@
-package initialize
-
-import (
-	"testing"
-)
-
-func TestCloudConfigUsersGithubUser(t *testing.T) {
-
-	contents := `
-users:
-  - name: elroy
-    coreos-ssh-import-github: bcwaldon
-`
-	cfg, err := NewCloudConfig(contents)
-	if err != nil {
-		t.Fatalf("Encountered unexpected error: %v", err)
-	}
-
-	if len(cfg.Users) != 1 {
-		t.Fatalf("Parsed %d users, expected 1", cfg.Users)
-	}
-
-	user := cfg.Users[0]
-
-	if user.Name != "elroy" {
-		t.Errorf("User name is %q, expected 'elroy'", user.Name)
-	}
-
-	if user.SSHImportGithubUser != "bcwaldon" {
-		t.Errorf("github user is %q, expected 'bcwaldon'", user.SSHImportGithubUser)
-	}
-}
--- a/initialize/locksmith.go
+++ b/initialize/locksmith.go
@@ -1,82 +0,0 @@
-package initialize
-
-import (
-	"bufio"
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path"
-	"strings"
-
-	"github.com/coreos/coreos-cloudinit/system"
-)
-
-const locksmithUnit = "locksmithd.service"
-
-// addStrategy creates an `/etc/coreos/update.conf` file with the requested
-// strategy via rewriting the file on disk or by starting from
-// `/usr/share/coreos/update.conf`.
-func addStrategy(strategy string, root string) error {
-	etcUpdate := path.Join(root, "etc", "coreos", "update.conf")
-	usrUpdate := path.Join(root, "usr", "share", "coreos", "update.conf")
-
-	tmp, err := ioutil.TempFile(path.Join(root, "etc", "coreos"), ".update.conf")
-	if err != nil {
-		return err
-	}
-	err = tmp.Chmod(0644)
-	if err != nil {
-		return err
-	}
-
-	conf, err := os.Open(etcUpdate)
-	if os.IsNotExist(err) {
-		conf, err = os.Open(usrUpdate)
-		if err != nil {
-			return err
-		}
-	}
-
-	scanner := bufio.NewScanner(conf)
-
-	sawStrat := false
-	stratLine := "REBOOT_STRATEGY="+strategy
-	for scanner.Scan() {
-		line := scanner.Text()
-		if strings.HasPrefix(line, "REBOOT_STRATEGY=") {
-			line = stratLine
-			sawStrat = true
-		}
-		fmt.Fprintln(tmp, line)
-		if err := scanner.Err(); err != nil {
-			return err
-		}
-	}
-
-	if !sawStrat {
-		fmt.Fprintln(tmp, stratLine)
-	}
-
-	return os.Rename(tmp.Name(), etcUpdate)
-}
-
-// WriteLocksmithConfig updates the `update.conf` file with a REBOOT_STRATEGY for locksmith.
-func WriteLocksmithConfig(strategy string, root string) error {
-	cmd := "restart"
-	if strategy == "off" {
-		err := system.MaskUnit(locksmithUnit, root)
-		if err != nil {
-			return err
-		}
-		cmd = "stop"
-	} else {
-		return addStrategy(strategy, root)
-	}
-	if err := system.DaemonReload(); err != nil {
-		return err
-	}
-	if _, err := system.RunUnitCommand(cmd, locksmithUnit); err != nil {
-		return err
-	}
-	return nil
-}
--- a/initialize/locksmith_test.go
+++ b/initialize/locksmith_test.go
@@ -1,92 +0,0 @@
-package initialize
-
-import (
-	"io/ioutil"
-	"os"
-	"path"
-	"testing"
-)
-
-const (
-	base = `SERVER=https://example.com
-GROUP=thegroupc`
-
-	configured = base + `
-REBOOT_STRATEGY=awesome
-`
-
-	expected = base + `
-REBOOT_STRATEGY=etcd-lock
-`
-)
-
-func setupFixtures(dir string) {
-	os.MkdirAll(path.Join(dir, "usr", "share", "coreos"), 0755)
-	os.MkdirAll(path.Join(dir, "etc", "coreos"), 0755)
-	os.MkdirAll(path.Join(dir, "run", "systemd", "system"), 0755)
-
-	ioutil.WriteFile(path.Join(dir, "usr", "share", "coreos", "update.conf"), []byte(base), 0644)
-}
-
-func TestLocksmithEnvironmentWrittenToDisk(t *testing.T) {
-	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
-	if err != nil {
-		t.Fatalf("Unable to create tempdir: %v", err)
-	}
-	defer os.RemoveAll(dir)
-	setupFixtures(dir)
-
-	for i := 0; i < 2; i++ {
-		if i == 1 {
-			err = ioutil.WriteFile(path.Join(dir, "etc", "coreos", "update.conf"), []byte(configured), 0644)
-			if err != nil {
-				t.Fatal(err)
-			}
-		}
-
-		if err := WriteLocksmithConfig("etcd-lock", dir); err != nil {
-			t.Fatalf("Processing of LocksmithEnvironment failed: %v", err)
-		}
-
-		fullPath := path.Join(dir, "etc", "coreos", "update.conf")
-
-		fi, err := os.Stat(fullPath)
-		if err != nil {
-			t.Fatalf("Unable to stat file: %v", err)
-		}
-
-		if fi.Mode() != os.FileMode(0644) {
-			t.Errorf("File has incorrect mode: %v", fi.Mode())
-		}
-
-		contents, err := ioutil.ReadFile(fullPath)
-		if err != nil {
-			t.Fatalf("Unable to read expected file: %v", err)
-		}
-
-		if string(contents) != expected {
-			t.Fatalf("File has incorrect contents, got %v, wanted %v", string(contents), expected)
-		}
-	}
-}
-func TestLocksmithEnvironmentMasked(t *testing.T) {
-	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
-	if err != nil {
-		t.Fatalf("Unable to create tempdir: %v", err)
-	}
-	defer os.RemoveAll(dir)
-	setupFixtures(dir)
-
-	if err := WriteLocksmithConfig("off", dir); err != nil {
-		t.Fatalf("Processing of LocksmithEnvironment failed: %v", err)
-	}
-
-	fullPath := path.Join(dir, "etc", "systemd", "system", "locksmithd.service")
-	target, err := os.Readlink(fullPath)
-	if err != nil {
-		t.Fatalf("Unable to read link %v", err)
-	}
-	if target != "/dev/null" {
-		t.Fatalf("Locksmith not masked, unit target %v", target)
-	}
-}
--- a/initialize/manage_etc_hosts.go
+++ b/initialize/manage_etc_hosts.go
@@ -1,44 +0,0 @@
-package initialize
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"path"
-
-	"github.com/coreos/coreos-cloudinit/system"
-)
-
-const DefaultIpv4Address = "127.0.0.1"
-
-func generateEtcHosts(option string) (out string, err error) {
-	if option != "localhost" {
-		return "", errors.New("Invalid option to manage_etc_hosts")
-	}
-
-	// use the operating system hostname
-	hostname, err := os.Hostname()
-	if err != nil {
-		return "", err
-	}
-
-	return fmt.Sprintf("%s %s\n", DefaultIpv4Address, hostname), nil
-
-}
-
-// Write an /etc/hosts file
-func WriteEtcHosts(option string, root string) error {
-
-	etcHosts, err := generateEtcHosts(option)
-	if err != nil {
-		return err
-	}
-
-	file := system.File{
-		Path:               path.Join(root, "etc", "hosts"),
-		RawFilePermissions: "0644",
-		Content:            etcHosts,
-	}
-
-	return system.WriteFile(&file)
-}
--- a/initialize/manage_etc_hosts_test.go
+++ b/initialize/manage_etc_hosts_test.go
@@ -1,76 +0,0 @@
-package initialize
-
-import (
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path"
-	"testing"
-)
-
-func TestCloudConfigManageEtcHosts(t *testing.T) {
-	contents := `
-manage_etc_hosts: localhost
-`
-	cfg, err := NewCloudConfig(contents)
-	if err != nil {
-		t.Fatalf("Encountered unexpected error: %v", err)
-	}
-
-	manageEtcHosts := cfg.ManageEtcHosts
-
-	if manageEtcHosts != "localhost" {
-		t.Errorf("ManageEtcHosts value is %q, expected 'localhost'", manageEtcHosts)
-	}
-}
-
-func TestManageEtcHostsInvalidValue(t *testing.T) {
-	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
-	if err != nil {
-		t.Fatalf("Unable to create tempdir: %v", err)
-	}
-	defer rmdir(dir)
-
-	if err := WriteEtcHosts("invalid", dir); err == nil {
-		t.Fatalf("WriteEtcHosts succeeded with invalid value: %v", err)
-	}
-}
-
-func TestEtcHostsWrittenToDisk(t *testing.T) {
-	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
-	if err != nil {
-		t.Fatalf("Unable to create tempdir: %v", err)
-	}
-	defer rmdir(dir)
-
-	if err := WriteEtcHosts("localhost", dir); err != nil {
-		t.Fatalf("WriteEtcHosts failed: %v", err)
-	}
-
-	fullPath := path.Join(dir, "etc", "hosts")
-
-	fi, err := os.Stat(fullPath)
-	if err != nil {
-		t.Fatalf("Unable to stat file: %v", err)
-	}
-
-	if fi.Mode() != os.FileMode(0644) {
-		t.Errorf("File has incorrect mode: %v", fi.Mode())
-	}
-
-	contents, err := ioutil.ReadFile(fullPath)
-	if err != nil {
-		t.Fatalf("Unable to read expected file: %v", err)
-	}
-
-	hostname, err := os.Hostname()
-	if err != nil {
-		t.Fatalf("Unable to read OS hostname: %v", err)
-	}
-
-	expect := fmt.Sprintf("%s %s\n", DefaultIpv4Address, hostname)
-
-	if string(contents) != expect {
-		t.Fatalf("File has incorrect contents")
-	}
-}
--- a/initialize/meta_data.go
+++ b/initialize/meta_data.go
@@ -0,0 +1,74 @@
+package initialize
+
+import (
+	"encoding/json"
+	"sort"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+// ParseMetaData parses a JSON blob in the OpenStack metadata service format,
+// and converts it to a partially hydrated CloudConfig.
+func ParseMetaData(contents string) (*config.CloudConfig, error) {
+	if len(contents) == 0 {
+		return nil, nil
+	}
+	var metadata struct {
+		SSHAuthorizedKeyMap map[string]string `json:"public_keys"`
+		Hostname            string            `json:"hostname"`
+		NetworkConfig       struct {
+			ContentPath string `json:"content_path"`
+		} `json:"network_config"`
+	}
+	if err := json.Unmarshal([]byte(contents), &metadata); err != nil {
+		return nil, err
+	}
+
+	var cfg config.CloudConfig
+	if len(metadata.SSHAuthorizedKeyMap) > 0 {
+		cfg.SSHAuthorizedKeys = make([]string, 0, len(metadata.SSHAuthorizedKeyMap))
+		for _, name := range sortedKeys(metadata.SSHAuthorizedKeyMap) {
+			cfg.SSHAuthorizedKeys = append(cfg.SSHAuthorizedKeys, metadata.SSHAuthorizedKeyMap[name])
+		}
+	}
+	cfg.Hostname = metadata.Hostname
+	cfg.NetworkConfigPath = metadata.NetworkConfig.ContentPath
+	return &cfg, nil
+}
+
+// ExtractIPsFromMetaData parses a JSON blob in the OpenStack metadata service
+// format and returns a substitution map possibly containing private_ipv4,
+// public_ipv4, private_ipv6, and public_ipv6 addresses.
+func ExtractIPsFromMetadata(contents []byte) (map[string]string, error) {
+	var ips struct {
+		PublicIPv4  string `json:"public-ipv4"`
+		PrivateIPv4 string `json:"local-ipv4"`
+		PublicIPv6  string `json:"public-ipv6"`
+		PrivateIPv6 string `json:"local-ipv6"`
+	}
+	if err := json.Unmarshal(contents, &ips); err != nil {
+		return nil, err
+	}
+	m := make(map[string]string)
+	if ips.PrivateIPv4 != "" {
+		m["$private_ipv4"] = ips.PrivateIPv4
+	}
+	if ips.PublicIPv4 != "" {
+		m["$public_ipv4"] = ips.PublicIPv4
+	}
+	if ips.PrivateIPv6 != "" {
+		m["$private_ipv6"] = ips.PrivateIPv6
+	}
+	if ips.PublicIPv6 != "" {
+		m["$public_ipv6"] = ips.PublicIPv6
+	}
+	return m, nil
+}
+
+func sortedKeys(m map[string]string) (keys []string) {
+	for key := range m {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	return
+}
--- a/initialize/meta_data_test.go
+++ b/initialize/meta_data_test.go
@@ -0,0 +1,73 @@
+package initialize
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+func TestParseMetadata(t *testing.T) {
+	for i, tt := range []struct {
+		in   string
+		want *config.CloudConfig
+		err  bool
+	}{
+		{"", nil, false},
+		{`garbage, invalid json`, nil, true},
+		{`{"foo": "bar"}`, &config.CloudConfig{}, false},
+		{`{"network_config": {"content_path": "asdf"}}`, &config.CloudConfig{NetworkConfigPath: "asdf"}, false},
+		{`{"hostname": "turkleton"}`, &config.CloudConfig{Hostname: "turkleton"}, false},
+		{`{"public_keys": {"jack": "jill", "bob": "alice"}}`, &config.CloudConfig{SSHAuthorizedKeys: []string{"alice", "jill"}}, false},
+		{`{"unknown": "thing", "hostname": "my_host", "public_keys": {"do": "re", "mi": "fa"}, "network_config": {"content_path": "/root", "blah": "zzz"}}`, &config.CloudConfig{SSHAuthorizedKeys: []string{"re", "fa"}, Hostname: "my_host", NetworkConfigPath: "/root"}, false},
+	} {
+		got, err := ParseMetaData(tt.in)
+		if tt.err != (err != nil) {
+			t.Errorf("case #%d: bad error state: got %t, want %t (err=%v)", i, (err != nil), tt.err, err)
+		}
+		if got == nil {
+			if tt.want != nil {
+				t.Errorf("case #%d: unexpected nil output", i)
+			}
+		} else if tt.want == nil {
+			t.Errorf("case #%d: unexpected non-nil output", i)
+		} else {
+			if !reflect.DeepEqual(*got, *tt.want) {
+				t.Errorf("case #%d: bad output:\ngot\n%v\nwant\n%v", i, *got, *tt.want)
+			}
+		}
+	}
+
+}
+
+func TestExtractIPsFromMetadata(t *testing.T) {
+	for i, tt := range []struct {
+		in  []byte
+		err bool
+		out map[string]string
+	}{
+		{
+			[]byte(`{"public-ipv4": "12.34.56.78", "local-ipv4": "1.2.3.4", "public-ipv6": "1234::", "local-ipv6": "5678::"}`),
+			false,
+			map[string]string{"$public_ipv4": "12.34.56.78", "$private_ipv4": "1.2.3.4", "$public_ipv6": "1234::", "$private_ipv6": "5678::"},
+		},
+		{
+			[]byte(`{"local-ipv4": "127.0.0.1", "something_else": "don't care"}`),
+			false,
+			map[string]string{"$private_ipv4": "127.0.0.1"},
+		},
+		{
+			[]byte(`garbage`),
+			true,
+			nil,
+		},
+	} {
+		got, err := ExtractIPsFromMetadata(tt.in)
+		if (err != nil) != tt.err {
+			t.Errorf("bad error state (got %t, want %t)", err != nil, tt.err)
+		}
+		if !reflect.DeepEqual(got, tt.out) {
+			t.Errorf("case %d: got %s, want %s", i, got, tt.out)
+		}
+	}
+}
--- a/initialize/oem.go
+++ b/initialize/oem.go
@@ -1,39 +0,0 @@
-package initialize
-
-import (
-	"fmt"
-	"path"
-	"strings"
-
-	"github.com/coreos/coreos-cloudinit/system"
-)
-
-type OEMRelease struct {
-	ID           string `yaml:"id"`
-	Name         string `yaml:"name"`
-	VersionID    string `yaml:"version-id"`
-	HomeURL      string `yaml:"home-url"`
-	BugReportURL string `yaml:"bug-report-url"`
-}
-
-func (oem *OEMRelease) String() string {
-	fields := []string{
-		fmt.Sprintf("ID=%s", oem.ID),
-		fmt.Sprintf("VERSION_ID=%s", oem.VersionID),
-		fmt.Sprintf("NAME=%q", oem.Name),
-		fmt.Sprintf("HOME_URL=%q", oem.HomeURL),
-		fmt.Sprintf("BUG_REPORT_URL=%q", oem.BugReportURL),
-	}
-
-	return strings.Join(fields, "\n") + "\n"
-}
-
-func WriteOEMRelease(oem *OEMRelease, root string) error {
-	file := system.File{
-		Path:               path.Join(root, "etc", "oem-release"),
-		RawFilePermissions: "0644",
-		Content:            oem.String(),
-	}
-
-	return system.WriteFile(&file)
-}
--- a/initialize/oem_test.go
+++ b/initialize/oem_test.go
@@ -1,53 +0,0 @@
-package initialize
-
-import (
-	"io/ioutil"
-	"os"
-	"path"
-	"testing"
-)
-
-func TestOEMReleaseWrittenToDisk(t *testing.T) {
-	oem := OEMRelease{
-		ID:           "rackspace",
-		Name:         "Rackspace Cloud Servers",
-		VersionID:    "168.0.0",
-		HomeURL:      "https://www.rackspace.com/cloud/servers/",
-		BugReportURL: "https://github.com/coreos/coreos-overlay",
-	}
-	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
-	if err != nil {
-		t.Fatalf("Unable to create tempdir: %v", err)
-	}
-	defer os.RemoveAll(dir)
-
-	if err := WriteOEMRelease(&oem, dir); err != nil {
-		t.Fatalf("Processing of EtcdEnvironment failed: %v", err)
-	}
-
-	fullPath := path.Join(dir, "etc", "oem-release")
-
-	fi, err := os.Stat(fullPath)
-	if err != nil {
-		t.Fatalf("Unable to stat file: %v", err)
-	}
-
-	if fi.Mode() != os.FileMode(0644) {
-		t.Errorf("File has incorrect mode: %v", fi.Mode())
-	}
-
-	contents, err := ioutil.ReadFile(fullPath)
-	if err != nil {
-		t.Fatalf("Unable to read expected file: %v", err)
-	}
-
-	expect := `ID=rackspace
-VERSION_ID=168.0.0
-NAME="Rackspace Cloud Servers"
-HOME_URL="https://www.rackspace.com/cloud/servers/"
-BUG_REPORT_URL="https://github.com/coreos/coreos-overlay"
-`
-	if string(contents) != expect {
-		t.Fatalf("File has incorrect contents")
-	}
-}
--- a/initialize/ssh_keys.go
+++ b/initialize/ssh_keys.go
@@ -3,9 +3,8 @@ package initialize
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
-	"net/http"

+	"github.com/coreos/coreos-cloudinit/pkg"
 	"github.com/coreos/coreos-cloudinit/system"
 )

@@ -25,22 +24,19 @@ func SSHImportKeysFromURL(system_user string, url string) error {
 }

 func fetchUserKeys(url string) ([]string, error) {
-	res, err := http.Get(url)
-	defer res.Body.Close()
+	client := pkg.NewHttpClient()
+	data, err := client.GetRetry(url)
 	if err != nil {
 		return nil, err
 	}
-	body, err := ioutil.ReadAll(res.Body)
-	if err != nil {
-		return nil, err
-	}
-	var data []UserKey
-	err = json.Unmarshal(body, &data)
+
+	var userKeys []UserKey
+	err = json.Unmarshal(data, &userKeys)
 	if err != nil {
 		return nil, err
 	}
 	keys := make([]string, 0)
-	for _, key := range data {
+	for _, key := range userKeys {
 		keys = append(keys, key.Key)
 	}
 	return keys, err
--- a/initialize/ssh_keys_test.go
+++ b/initialize/ssh_keys_test.go
@@ -39,31 +39,4 @@ func TestCloudConfigUsersUrlMarshal(t *testing.T) {
 	if keys[2] != expected {
 		t.Fatalf("expected %s, got %s", expected, keys[2])
 	}
-
-}
-func TestCloudConfigUsersSSHImportURL(t *testing.T) {
-
-	contents := `
-users:
-  - name: elroy
-    coreos-ssh-import-url: https://token:x-auth-token@github.enterprise.com/api/v3/polvi/keys
-`
-	cfg, err := NewCloudConfig(contents)
-	if err != nil {
-		t.Fatalf("Encountered unexpected error: %v", err)
-	}
-
-	if len(cfg.Users) != 1 {
-		t.Fatalf("Parsed %d users, expected 1", cfg.Users)
-	}
-
-	user := cfg.Users[0]
-
-	if user.Name != "elroy" {
-		t.Errorf("User name is %q, expected 'elroy'", user.Name)
-	}
-
-	if user.SSHImportURL != "https://token:x-auth-token@github.enterprise.com/api/v3/polvi/keys" {
-		t.Errorf("ssh import url is %q, expected 'https://token:x-auth-token@github.enterprise.com/api/v3/polvi/keys'", user.SSHImportURL)
-	}
 }
--- a/initialize/user_data.go
+++ b/initialize/user_data.go
@@ -5,28 +5,27 @@ import (
 	"log"
 	"strings"

+	"github.com/coreos/coreos-cloudinit/config"
 	"github.com/coreos/coreos-cloudinit/system"
 )

 func ParseUserData(contents string) (interface{}, error) {
+	if len(contents) == 0 {
+		return nil, nil
+	}
 	header := strings.SplitN(contents, "\n", 2)[0]

 	// Explicitly trim the header so we can handle user-data from
 	// non-unix operating systems. The rest of the file is parsed
-	// by goyaml, which correctly handles CRLF.
+	// by yaml, which correctly handles CRLF.
 	header = strings.TrimSpace(header)

 	if strings.HasPrefix(header, "#!") {
 		log.Printf("Parsing user-data as script")
 		return system.Script(contents), nil
-
 	} else if header == "#cloud-config" {
 		log.Printf("Parsing user-data as cloud-config")
-		cfg, err := NewCloudConfig(contents)
-		if err != nil {
-			log.Fatal(err.Error())
-		}
-		return *cfg, nil
+		return config.NewCloudConfig(contents)
 	} else {
 		return nil, fmt.Errorf("Unrecognized user-data header: %s", header)
 	}
--- a/initialize/user_data_test.go
+++ b/initialize/user_data_test.go
@@ -2,6 +2,8 @@ package initialize

 import (
 	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
 )

 func TestParseHeaderCRLF(t *testing.T) {
@@ -37,7 +39,7 @@ func TestParseConfigCRLF(t *testing.T) {
 		t.Fatalf("Failed parsing config: %v", err)
 	}

-	cfg := ud.(CloudConfig)
+	cfg := ud.(*config.CloudConfig)

 	if cfg.Hostname != "foo" {
 		t.Error("Failed parsing hostname from config")
@@ -47,3 +49,12 @@ func TestParseConfigCRLF(t *testing.T) {
 		t.Error("Parsed incorrect number of SSH keys")
 	}
 }
+
+func TestParseConfigEmpty(t *testing.T) {
+	i, e := ParseUserData(``)
+	if i != nil {
+		t.Error("ParseUserData of empty string returned non-nil unexpectedly")
+	} else if e != nil {
+		t.Error("ParseUserData of empty string returned error unexpectedly")
+	}
+}
--- a/initialize/workspace.go
+++ b/initialize/workspace.go
@@ -3,7 +3,9 @@ package initialize
 import (
 	"io/ioutil"
 	"path"
+	"strings"

+	"github.com/coreos/coreos-cloudinit/config"
 	"github.com/coreos/coreos-cloudinit/system"
 )

@@ -28,21 +30,23 @@ func PersistScriptInWorkspace(script system.Script, workspace string) (string, e
 	}
 	tmp.Close()

-	file := system.File{
-		Path: tmp.Name(),
+	relpath := strings.TrimPrefix(tmp.Name(), workspace)
+
+	file := system.File{config.File{
+		Path:               relpath,
 		RawFilePermissions: "0744",
 		Content:            string(script),
-	}
+	}}

-	err = system.WriteFile(&file)
-	return file.Path, err
+	return system.WriteFile(&file, workspace)
 }

 func PersistUnitNameInWorkspace(name string, workspace string) error {
-	file := system.File{
-		Path: path.Join(workspace, "scripts", "unit-name"),
+	file := system.File{config.File{
+		Path:               path.Join("scripts", "unit-name"),
 		RawFilePermissions: "0644",
 		Content:            name,
-	}
-	return system.WriteFile(&file)
+	}}
+	_, err := system.WriteFile(&file, workspace)
+	return err
 }
--- a/network/debian.go
+++ b/network/debian.go
@@ -0,0 +1,49 @@
+package network
+
+import (
+	"log"
+	"strings"
+)
+
+func ProcessDebianNetconf(config string) ([]InterfaceGenerator, error) {
+	log.Println("Processing Debian network config")
+	lines := formatConfig(config)
+	stanzas, err := parseStanzas(lines)
+	if err != nil {
+		return nil, err
+	}
+
+	interfaces := make([]*stanzaInterface, 0, len(stanzas))
+	for _, stanza := range stanzas {
+		switch s := stanza.(type) {
+		case *stanzaInterface:
+			interfaces = append(interfaces, s)
+		}
+	}
+	log.Printf("Parsed %d network interfaces\n", len(interfaces))
+
+	log.Println("Processed Debian network config")
+	return buildInterfaces(interfaces), nil
+}
+
+func formatConfig(config string) []string {
+	lines := []string{}
+	config = strings.Replace(config, "\\\n", "", -1)
+	for config != "" {
+		split := strings.SplitN(config, "\n", 2)
+		line := strings.TrimSpace(split[0])
+
+		if len(split) == 2 {
+			config = split[1]
+		} else {
+			config = ""
+		}
+
+		if strings.HasPrefix(line, "#") || line == "" {
+			continue
+		}
+
+		lines = append(lines, line)
+	}
+	return lines
+}
--- a/network/debian_test.go
+++ b/network/debian_test.go
@@ -0,0 +1,42 @@
+package network
+
+import (
+	"testing"
+)
+
+func TestFormatConfigs(t *testing.T) {
+	for in, n := range map[string]int{
+		"":                                                    0,
+		"line1\\\nis long":                                    1,
+		"#comment":                                            0,
+		"#comment\\\ncomment":                                 0,
+		"  #comment \\\n comment\nline 1\nline 2\\\n is long": 2,
+	} {
+		lines := formatConfig(in)
+		if len(lines) != n {
+			t.Fatalf("bad number of lines for config %q: got %d, want %d", in, len(lines), n)
+		}
+	}
+}
+
+func TestProcessDebianNetconf(t *testing.T) {
+	for _, tt := range []struct {
+		in   string
+		fail bool
+		n    int
+	}{
+		{"", false, 0},
+		{"iface", true, -1},
+		{"auto eth1\nauto eth2", false, 0},
+		{"iface eth1 inet manual", false, 1},
+	} {
+		interfaces, err := ProcessDebianNetconf(tt.in)
+		failed := err != nil
+		if tt.fail != failed {
+			t.Fatalf("bad failure state for %q: got %b, want %b", failed, tt.fail)
+		}
+		if tt.n != -1 && tt.n != len(interfaces) {
+			t.Fatalf("bad number of interfaces for %q: got %d, want %q", tt.in, len(interfaces), tt.n)
+		}
+	}
+}
--- a/network/digitalocean.go
+++ b/network/digitalocean.go
@@ -0,0 +1,142 @@
+package network
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"net"
+
+	"github.com/coreos/coreos-cloudinit/datasource/metadata/digitalocean"
+)
+
+func ProcessDigitalOceanNetconf(config string) ([]InterfaceGenerator, error) {
+	log.Println("Processing DigitalOcean network config")
+	if config == "" {
+		return nil, nil
+	}
+
+	var cfg digitalocean.Metadata
+	if err := json.Unmarshal([]byte(config), &cfg); err != nil {
+		return nil, err
+	}
+
+	log.Println("Parsing nameservers")
+	nameservers, err := parseNameservers(cfg.DNS)
+	if err != nil {
+		return nil, err
+	}
+	log.Printf("Parsed %d nameservers\n", len(nameservers))
+
+	log.Println("Parsing interfaces")
+	generators, err := parseInterfaces(cfg.Interfaces, nameservers)
+	if err != nil {
+		return nil, err
+	}
+	log.Printf("Parsed %d network interfaces\n", len(generators))
+
+	log.Println("Processed DigitalOcean network config")
+	return generators, nil
+}
+
+func parseNameservers(cfg digitalocean.DNS) ([]net.IP, error) {
+	nameservers := make([]net.IP, 0, len(cfg.Nameservers))
+	for _, ns := range cfg.Nameservers {
+		if ip := net.ParseIP(ns); ip == nil {
+			return nil, fmt.Errorf("could not parse %q as nameserver IP address", ns)
+		} else {
+			nameservers = append(nameservers, ip)
+		}
+	}
+	return nameservers, nil
+}
+
+func parseInterfaces(cfg digitalocean.Interfaces, nameservers []net.IP) ([]InterfaceGenerator, error) {
+	generators := make([]InterfaceGenerator, 0, len(cfg.Public)+len(cfg.Private))
+	for _, iface := range cfg.Public {
+		if generator, err := parseInterface(iface, nameservers, true); err == nil {
+			generators = append(generators, &physicalInterface{*generator})
+		} else {
+			return nil, err
+		}
+	}
+	for _, iface := range cfg.Private {
+		if generator, err := parseInterface(iface, []net.IP{}, false); err == nil {
+			generators = append(generators, &physicalInterface{*generator})
+		} else {
+			return nil, err
+		}
+	}
+	return generators, nil
+}
+
+func parseInterface(iface digitalocean.Interface, nameservers []net.IP, useRoute bool) (*logicalInterface, error) {
+	routes := make([]route, 0)
+	addresses := make([]net.IPNet, 0)
+	if iface.IPv4 != nil {
+		var ip, mask, gateway net.IP
+		if ip = net.ParseIP(iface.IPv4.IPAddress); ip == nil {
+			return nil, fmt.Errorf("could not parse %q as IPv4 address", iface.IPv4.IPAddress)
+		}
+		if mask = net.ParseIP(iface.IPv4.Netmask); mask == nil {
+			return nil, fmt.Errorf("could not parse %q as IPv4 mask", iface.IPv4.Netmask)
+		}
+		addresses = append(addresses, net.IPNet{
+			IP:   ip,
+			Mask: net.IPMask(mask),
+		})
+
+		if useRoute {
+			if gateway = net.ParseIP(iface.IPv4.Gateway); gateway == nil {
+				return nil, fmt.Errorf("could not parse %q as IPv4 gateway", iface.IPv4.Gateway)
+			}
+			routes = append(routes, route{
+				destination: net.IPNet{
+					IP:   net.IPv4zero,
+					Mask: net.IPMask(net.IPv4zero),
+				},
+				gateway: gateway,
+			})
+		}
+	}
+	if iface.IPv6 != nil {
+		var ip, gateway net.IP
+		if ip = net.ParseIP(iface.IPv6.IPAddress); ip == nil {
+			return nil, fmt.Errorf("could not parse %q as IPv6 address", iface.IPv6.IPAddress)
+		}
+		addresses = append(addresses, net.IPNet{
+			IP:   ip,
+			Mask: net.CIDRMask(iface.IPv6.Cidr, net.IPv6len*8),
+		})
+
+		if useRoute {
+			if gateway = net.ParseIP(iface.IPv6.Gateway); gateway == nil {
+				return nil, fmt.Errorf("could not parse %q as IPv6 gateway", iface.IPv6.Gateway)
+			}
+			routes = append(routes, route{
+				destination: net.IPNet{
+					IP:   net.IPv6zero,
+					Mask: net.IPMask(net.IPv6zero),
+				},
+				gateway: gateway,
+			})
+		}
+	}
+
+	hwaddr, err := net.ParseMAC(iface.MAC)
+	if err != nil {
+		return nil, err
+	}
+
+	if nameservers == nil {
+		nameservers = []net.IP{}
+	}
+
+	return &logicalInterface{
+		hwaddr: hwaddr,
+		config: configMethodStatic{
+			addresses:   addresses,
+			nameservers: nameservers,
+			routes:      routes,
+		},
+	}, nil
+}
--- a/network/digitalocean_test.go
+++ b/network/digitalocean_test.go
@@ -0,0 +1,367 @@
+package network
+
+import (
+	"errors"
+	"net"
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/datasource/metadata/digitalocean"
+)
+
+func TestParseNameservers(t *testing.T) {
+	for _, tt := range []struct {
+		dns digitalocean.DNS
+		nss []net.IP
+		err error
+	}{
+		{
+			dns: digitalocean.DNS{},
+			nss: []net.IP{},
+		},
+		{
+			dns: digitalocean.DNS{[]string{"1.2.3.4"}},
+			nss: []net.IP{net.ParseIP("1.2.3.4")},
+		},
+		{
+			dns: digitalocean.DNS{[]string{"bad"}},
+			err: errors.New("could not parse \"bad\" as nameserver IP address"),
+		},
+	} {
+		nss, err := parseNameservers(tt.dns)
+		if !errorsEqual(tt.err, err) {
+			t.Fatalf("bad error (%+v): want %q, got %q", tt.dns, tt.err, err)
+		}
+		if !reflect.DeepEqual(tt.nss, nss) {
+			t.Fatalf("bad nameservers (%+v): want %#v, got %#v", tt.dns, tt.nss, nss)
+		}
+	}
+}
+
+func TestParseInterface(t *testing.T) {
+	for _, tt := range []struct {
+		cfg      digitalocean.Interface
+		nss      []net.IP
+		useRoute bool
+		iface    *logicalInterface
+		err      error
+	}{
+		{
+			cfg: digitalocean.Interface{
+				MAC: "bad",
+			},
+			err: errors.New("invalid MAC address: bad"),
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+			},
+			nss: []net.IP{},
+			iface: &logicalInterface{
+				hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+				config: configMethodStatic{
+					addresses:   []net.IPNet{},
+					nameservers: []net.IP{},
+					routes:      []route{},
+				},
+			},
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+			},
+			useRoute: true,
+			nss:      []net.IP{net.ParseIP("1.2.3.4")},
+			iface: &logicalInterface{
+				hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+				config: configMethodStatic{
+					addresses:   []net.IPNet{},
+					nameservers: []net.IP{net.ParseIP("1.2.3.4")},
+					routes:      []route{},
+				},
+			},
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv4: &digitalocean.Address{
+					IPAddress: "bad",
+					Netmask:   "255.255.0.0",
+				},
+			},
+			nss: []net.IP{},
+			err: errors.New("could not parse \"bad\" as IPv4 address"),
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv4: &digitalocean.Address{
+					IPAddress: "1.2.3.4",
+					Netmask:   "bad",
+				},
+			},
+			nss: []net.IP{},
+			err: errors.New("could not parse \"bad\" as IPv4 mask"),
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv4: &digitalocean.Address{
+					IPAddress: "1.2.3.4",
+					Netmask:   "255.255.0.0",
+					Gateway:   "ignoreme",
+				},
+			},
+			nss: []net.IP{},
+			iface: &logicalInterface{
+				hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+				config: configMethodStatic{
+					addresses:   []net.IPNet{net.IPNet{net.ParseIP("1.2.3.4"), net.IPMask(net.ParseIP("255.255.0.0"))}},
+					nameservers: []net.IP{},
+					routes:      []route{},
+				},
+			},
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv4: &digitalocean.Address{
+					IPAddress: "1.2.3.4",
+					Netmask:   "255.255.0.0",
+					Gateway:   "bad",
+				},
+			},
+			useRoute: true,
+			nss:      []net.IP{},
+			err:      errors.New("could not parse \"bad\" as IPv4 gateway"),
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv4: &digitalocean.Address{
+					IPAddress: "1.2.3.4",
+					Netmask:   "255.255.0.0",
+					Gateway:   "5.6.7.8",
+				},
+			},
+			useRoute: true,
+			nss:      []net.IP{},
+			iface: &logicalInterface{
+				hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+				config: configMethodStatic{
+					addresses:   []net.IPNet{net.IPNet{net.ParseIP("1.2.3.4"), net.IPMask(net.ParseIP("255.255.0.0"))}},
+					nameservers: []net.IP{},
+					routes:      []route{route{net.IPNet{net.IPv4zero, net.IPMask(net.IPv4zero)}, net.ParseIP("5.6.7.8")}},
+				},
+			},
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv6: &digitalocean.Address{
+					IPAddress: "bad",
+					Cidr:      16,
+				},
+			},
+			nss: []net.IP{},
+			err: errors.New("could not parse \"bad\" as IPv6 address"),
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv6: &digitalocean.Address{
+					IPAddress: "fe00::",
+					Cidr:      16,
+					Gateway:   "ignoreme",
+				},
+			},
+			nss: []net.IP{},
+			iface: &logicalInterface{
+				hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+				config: configMethodStatic{
+					addresses:   []net.IPNet{net.IPNet{net.ParseIP("fe00::"), net.IPMask(net.ParseIP("ffff::"))}},
+					nameservers: []net.IP{},
+					routes:      []route{},
+				},
+			},
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv6: &digitalocean.Address{
+					IPAddress: "fe00::",
+					Cidr:      16,
+					Gateway:   "bad",
+				},
+			},
+			useRoute: true,
+			nss:      []net.IP{},
+			err:      errors.New("could not parse \"bad\" as IPv6 gateway"),
+		},
+		{
+			cfg: digitalocean.Interface{
+				MAC: "01:23:45:67:89:AB",
+				IPv6: &digitalocean.Address{
+					IPAddress: "fe00::",
+					Cidr:      16,
+					Gateway:   "fe00:1234::",
+				},
+			},
+			useRoute: true,
+			nss:      []net.IP{},
+			iface: &logicalInterface{
+				hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+				config: configMethodStatic{
+					addresses:   []net.IPNet{net.IPNet{net.ParseIP("fe00::"), net.IPMask(net.ParseIP("ffff::"))}},
+					nameservers: []net.IP{},
+					routes:      []route{route{net.IPNet{net.IPv6zero, net.IPMask(net.IPv6zero)}, net.ParseIP("fe00:1234::")}},
+				},
+			},
+		},
+	} {
+		iface, err := parseInterface(tt.cfg, tt.nss, tt.useRoute)
+		if !errorsEqual(tt.err, err) {
+			t.Fatalf("bad error (%+v): want %q, got %q", tt.cfg, tt.err, err)
+		}
+		if !reflect.DeepEqual(tt.iface, iface) {
+			t.Fatalf("bad interface (%+v): want %#v, got %#v", tt.cfg, tt.iface, iface)
+		}
+	}
+}
+
+func TestParseInterfaces(t *testing.T) {
+	for _, tt := range []struct {
+		cfg    digitalocean.Interfaces
+		nss    []net.IP
+		ifaces []InterfaceGenerator
+		err    error
+	}{
+		{
+			ifaces: []InterfaceGenerator{},
+		},
+		{
+			cfg: digitalocean.Interfaces{
+				Public: []digitalocean.Interface{{MAC: "01:23:45:67:89:AB"}},
+			},
+			ifaces: []InterfaceGenerator{
+				&physicalInterface{logicalInterface{
+					hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+					config: configMethodStatic{
+						addresses:   []net.IPNet{},
+						nameservers: []net.IP{},
+						routes:      []route{},
+					},
+				}},
+			},
+		},
+		{
+			cfg: digitalocean.Interfaces{
+				Private: []digitalocean.Interface{{MAC: "01:23:45:67:89:AB"}},
+			},
+			ifaces: []InterfaceGenerator{
+				&physicalInterface{logicalInterface{
+					hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+					config: configMethodStatic{
+						addresses:   []net.IPNet{},
+						nameservers: []net.IP{},
+						routes:      []route{},
+					},
+				}},
+			},
+		},
+		{
+			cfg: digitalocean.Interfaces{
+				Public: []digitalocean.Interface{{MAC: "01:23:45:67:89:AB"}},
+			},
+			nss: []net.IP{net.ParseIP("1.2.3.4")},
+			ifaces: []InterfaceGenerator{
+				&physicalInterface{logicalInterface{
+					hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+					config: configMethodStatic{
+						addresses:   []net.IPNet{},
+						nameservers: []net.IP{net.ParseIP("1.2.3.4")},
+						routes:      []route{},
+					},
+				}},
+			},
+		},
+		{
+			cfg: digitalocean.Interfaces{
+				Private: []digitalocean.Interface{{MAC: "01:23:45:67:89:AB"}},
+			},
+			nss: []net.IP{net.ParseIP("1.2.3.4")},
+			ifaces: []InterfaceGenerator{
+				&physicalInterface{logicalInterface{
+					hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}),
+					config: configMethodStatic{
+						addresses:   []net.IPNet{},
+						nameservers: []net.IP{},
+						routes:      []route{},
+					},
+				}},
+			},
+		},
+		{
+			cfg: digitalocean.Interfaces{
+				Public: []digitalocean.Interface{{MAC: "bad"}},
+			},
+			err: errors.New("invalid MAC address: bad"),
+		},
+		{
+			cfg: digitalocean.Interfaces{
+				Private: []digitalocean.Interface{{MAC: "bad"}},
+			},
+			err: errors.New("invalid MAC address: bad"),
+		},
+	} {
+		ifaces, err := parseInterfaces(tt.cfg, tt.nss)
+		if !errorsEqual(tt.err, err) {
+			t.Fatalf("bad error (%+v): want %q, got %q", tt.cfg, tt.err, err)
+		}
+		if !reflect.DeepEqual(tt.ifaces, ifaces) {
+			t.Fatalf("bad interfaces (%+v): want %#v, got %#v", tt.cfg, tt.ifaces, ifaces)
+		}
+	}
+}
+
+func TestProcessDigitalOceanNetconf(t *testing.T) {
+	for _, tt := range []struct {
+		cfg    string
+		ifaces []InterfaceGenerator
+		err    error
+	}{
+		{
+			cfg: ``,
+		},
+		{
+			cfg: `{"dns":{"nameservers":["bad"]}}`,
+			err: errors.New("could not parse \"bad\" as nameserver IP address"),
+		},
+		{
+			cfg: `{"interfaces":{"public":[{"ipv4":{"ip_address":"bad"}}]}}`,
+			err: errors.New("could not parse \"bad\" as IPv4 address"),
+		},
+		{
+			cfg:    `{}`,
+			ifaces: []InterfaceGenerator{},
+		},
+	} {
+		ifaces, err := ProcessDigitalOceanNetconf(tt.cfg)
+		if !errorsEqual(tt.err, err) {
+			t.Fatalf("bad error (%q): want %q, got %q", tt.cfg, tt.err, err)
+		}
+		if !reflect.DeepEqual(tt.ifaces, ifaces) {
+			t.Fatalf("bad interfaces (%q): want %#v, got %#v", tt.cfg, tt.ifaces, ifaces)
+		}
+	}
+}
+
+func errorsEqual(a, b error) bool {
+	if a == nil && b == nil {
+		return true
+	}
+	if (a != nil && b == nil) || (a == nil && b != nil) {
+		return false
+	}
+	return (a.Error() == b.Error())
+}
--- a/network/interface.go
+++ b/network/interface.go
@@ -0,0 +1,316 @@
+package network
+
+import (
+	"fmt"
+	"net"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+type InterfaceGenerator interface {
+	Name() string
+	Filename() string
+	Netdev() string
+	Link() string
+	Network() string
+	Type() string
+	ModprobeParams() string
+}
+
+type networkInterface interface {
+	InterfaceGenerator
+	Children() []networkInterface
+	setConfigDepth(int)
+}
+
+type logicalInterface struct {
+	name        string
+	hwaddr      net.HardwareAddr
+	config      configMethod
+	children    []networkInterface
+	configDepth int
+}
+
+func (i *logicalInterface) Name() string {
+	return i.name
+}
+
+func (i *logicalInterface) Network() string {
+	config := fmt.Sprintln("[Match]")
+	if i.name != "" {
+		config += fmt.Sprintf("Name=%s\n", i.name)
+	}
+	if i.hwaddr != nil {
+		config += fmt.Sprintf("MACAddress=%s\n", i.hwaddr)
+	}
+	config += "\n[Network]\n"
+
+	for _, child := range i.children {
+		switch iface := child.(type) {
+		case *vlanInterface:
+			config += fmt.Sprintf("VLAN=%s\n", iface.name)
+		case *bondInterface:
+			config += fmt.Sprintf("Bond=%s\n", iface.name)
+		}
+	}
+
+	switch conf := i.config.(type) {
+	case configMethodStatic:
+		for _, nameserver := range conf.nameservers {
+			config += fmt.Sprintf("DNS=%s\n", nameserver)
+		}
+		for _, addr := range conf.addresses {
+			config += fmt.Sprintf("\n[Address]\nAddress=%s\n", addr.String())
+		}
+		for _, route := range conf.routes {
+			config += fmt.Sprintf("\n[Route]\nDestination=%s\nGateway=%s\n", route.destination.String(), route.gateway)
+		}
+	case configMethodDHCP:
+		config += "DHCP=true\n"
+	}
+
+	return config
+}
+
+func (i *logicalInterface) Link() string {
+	return ""
+}
+
+func (i *logicalInterface) Netdev() string {
+	return ""
+}
+
+func (i *logicalInterface) Filename() string {
+	name := i.name
+	if name == "" {
+		name = i.hwaddr.String()
+	}
+	return fmt.Sprintf("%02x-%s", i.configDepth, name)
+}
+
+func (i *logicalInterface) Children() []networkInterface {
+	return i.children
+}
+
+func (i *logicalInterface) ModprobeParams() string {
+	return ""
+}
+
+func (i *logicalInterface) setConfigDepth(depth int) {
+	i.configDepth = depth
+}
+
+type physicalInterface struct {
+	logicalInterface
+}
+
+func (p *physicalInterface) Type() string {
+	return "physical"
+}
+
+type bondInterface struct {
+	logicalInterface
+	slaves  []string
+	options map[string]string
+}
+
+func (b *bondInterface) Netdev() string {
+	return fmt.Sprintf("[NetDev]\nKind=bond\nName=%s\n", b.name)
+}
+
+func (b *bondInterface) Type() string {
+	return "bond"
+}
+
+func (b *bondInterface) ModprobeParams() string {
+	params := ""
+	for _, name := range sortedKeys(b.options) {
+		params += fmt.Sprintf("%s=%s ", name, b.options[name])
+	}
+	params = strings.TrimSuffix(params, " ")
+	return params
+}
+
+type vlanInterface struct {
+	logicalInterface
+	id        int
+	rawDevice string
+}
+
+func (v *vlanInterface) Netdev() string {
+	config := fmt.Sprintf("[NetDev]\nKind=vlan\nName=%s\n", v.name)
+	switch c := v.config.(type) {
+	case configMethodStatic:
+		if c.hwaddress != nil {
+			config += fmt.Sprintf("MACAddress=%s\n", c.hwaddress)
+		}
+	case configMethodDHCP:
+		if c.hwaddress != nil {
+			config += fmt.Sprintf("MACAddress=%s\n", c.hwaddress)
+		}
+	}
+	config += fmt.Sprintf("\n[VLAN]\nId=%d\n", v.id)
+	return config
+}
+
+func (v *vlanInterface) Type() string {
+	return "vlan"
+}
+
+func buildInterfaces(stanzas []*stanzaInterface) []InterfaceGenerator {
+	interfaceMap := createInterfaces(stanzas)
+	linkAncestors(interfaceMap)
+	markConfigDepths(interfaceMap)
+
+	interfaces := make([]InterfaceGenerator, 0, len(interfaceMap))
+	for _, name := range sortedInterfaces(interfaceMap) {
+		interfaces = append(interfaces, interfaceMap[name])
+	}
+
+	return interfaces
+}
+
+func createInterfaces(stanzas []*stanzaInterface) map[string]networkInterface {
+	interfaceMap := make(map[string]networkInterface)
+	for _, iface := range stanzas {
+		switch iface.kind {
+		case interfaceBond:
+			bondOptions := make(map[string]string)
+			for _, k := range []string{"mode", "miimon", "lacp-rate"} {
+				if v, ok := iface.options["bond-"+k]; ok && len(v) > 0 {
+					bondOptions[k] = v[0]
+				}
+			}
+			interfaceMap[iface.name] = &bondInterface{
+				logicalInterface{
+					name:     iface.name,
+					config:   iface.configMethod,
+					children: []networkInterface{},
+				},
+				iface.options["bond-slaves"],
+				bondOptions,
+			}
+			for _, slave := range iface.options["bond-slaves"] {
+				if _, ok := interfaceMap[slave]; !ok {
+					interfaceMap[slave] = &physicalInterface{
+						logicalInterface{
+							name:     slave,
+							config:   configMethodManual{},
+							children: []networkInterface{},
+						},
+					}
+				}
+			}
+
+		case interfacePhysical:
+			if _, ok := iface.configMethod.(configMethodLoopback); ok {
+				continue
+			}
+			interfaceMap[iface.name] = &physicalInterface{
+				logicalInterface{
+					name:     iface.name,
+					config:   iface.configMethod,
+					children: []networkInterface{},
+				},
+			}
+
+		case interfaceVLAN:
+			var rawDevice string
+			id, _ := strconv.Atoi(iface.options["id"][0])
+			if device := iface.options["raw_device"]; len(device) == 1 {
+				rawDevice = device[0]
+				if _, ok := interfaceMap[rawDevice]; !ok {
+					interfaceMap[rawDevice] = &physicalInterface{
+						logicalInterface{
+							name:     rawDevice,
+							config:   configMethodManual{},
+							children: []networkInterface{},
+						},
+					}
+				}
+			}
+			interfaceMap[iface.name] = &vlanInterface{
+				logicalInterface{
+					name:     iface.name,
+					config:   iface.configMethod,
+					children: []networkInterface{},
+				},
+				id,
+				rawDevice,
+			}
+		}
+	}
+	return interfaceMap
+}
+
+func linkAncestors(interfaceMap map[string]networkInterface) {
+	for _, name := range sortedInterfaces(interfaceMap) {
+		iface := interfaceMap[name]
+		switch i := iface.(type) {
+		case *vlanInterface:
+			if parent, ok := interfaceMap[i.rawDevice]; ok {
+				switch p := parent.(type) {
+				case *physicalInterface:
+					p.children = append(p.children, iface)
+				case *bondInterface:
+					p.children = append(p.children, iface)
+				}
+			}
+		case *bondInterface:
+			for _, slave := range i.slaves {
+				if parent, ok := interfaceMap[slave]; ok {
+					switch p := parent.(type) {
+					case *physicalInterface:
+						p.children = append(p.children, iface)
+					case *bondInterface:
+						p.children = append(p.children, iface)
+					}
+				}
+			}
+		}
+	}
+}
+
+func markConfigDepths(interfaceMap map[string]networkInterface) {
+	rootInterfaceMap := make(map[string]networkInterface)
+	for k, v := range interfaceMap {
+		rootInterfaceMap[k] = v
+	}
+
+	for _, iface := range interfaceMap {
+		for _, child := range iface.Children() {
+			delete(rootInterfaceMap, child.Name())
+		}
+	}
+	for _, iface := range rootInterfaceMap {
+		setDepth(iface)
+	}
+}
+
+func setDepth(iface networkInterface) int {
+	maxDepth := 0
+	for _, child := range iface.Children() {
+		if depth := setDepth(child); depth > maxDepth {
+			maxDepth = depth
+		}
+	}
+	iface.setConfigDepth(maxDepth)
+	return (maxDepth + 1)
+}
+
+func sortedKeys(m map[string]string) (keys []string) {
+	for key := range m {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	return
+}
+
+func sortedInterfaces(m map[string]networkInterface) (keys []string) {
+	for key := range m {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	return
+}
--- a/network/interface_test.go
+++ b/network/interface_test.go
@@ -0,0 +1,354 @@
+package network
+
+import (
+	"net"
+	"reflect"
+	"testing"
+)
+
+func TestInterfaceGenerators(t *testing.T) {
+	for _, tt := range []struct {
+		name    string
+		netdev  string
+		link    string
+		network string
+		kind    string
+		iface   InterfaceGenerator
+	}{
+		{
+			name:    "",
+			network: "[Match]\nMACAddress=00:01:02:03:04:05\n\n[Network]\n",
+			kind:    "physical",
+			iface: &physicalInterface{logicalInterface{
+				hwaddr: net.HardwareAddr([]byte{0, 1, 2, 3, 4, 5}),
+			}},
+		},
+		{
+			name:    "testname",
+			network: "[Match]\nName=testname\n\n[Network]\nBond=testbond1\nVLAN=testvlan1\nVLAN=testvlan2\n",
+			kind:    "physical",
+			iface: &physicalInterface{logicalInterface{
+				name: "testname",
+				children: []networkInterface{
+					&bondInterface{logicalInterface: logicalInterface{name: "testbond1"}},
+					&vlanInterface{logicalInterface: logicalInterface{name: "testvlan1"}, id: 1},
+					&vlanInterface{logicalInterface: logicalInterface{name: "testvlan2"}, id: 1},
+				},
+			}},
+		},
+		{
+			name:    "testname",
+			netdev:  "[NetDev]\nKind=bond\nName=testname\n",
+			network: "[Match]\nName=testname\n\n[Network]\nBond=testbond1\nVLAN=testvlan1\nVLAN=testvlan2\nDHCP=true\n",
+			kind:    "bond",
+			iface: &bondInterface{logicalInterface: logicalInterface{
+				name:   "testname",
+				config: configMethodDHCP{},
+				children: []networkInterface{
+					&bondInterface{logicalInterface: logicalInterface{name: "testbond1"}},
+					&vlanInterface{logicalInterface: logicalInterface{name: "testvlan1"}, id: 1},
+					&vlanInterface{logicalInterface: logicalInterface{name: "testvlan2"}, id: 1},
+				},
+			}},
+		},
+		{
+			name:    "testname",
+			netdev:  "[NetDev]\nKind=vlan\nName=testname\n\n[VLAN]\nId=1\n",
+			network: "[Match]\nName=testname\n\n[Network]\n",
+			kind:    "vlan",
+			iface:   &vlanInterface{logicalInterface{name: "testname"}, 1, ""},
+		},
+		{
+			name:    "testname",
+			netdev:  "[NetDev]\nKind=vlan\nName=testname\nMACAddress=00:01:02:03:04:05\n\n[VLAN]\nId=1\n",
+			network: "[Match]\nName=testname\n\n[Network]\n",
+			kind:    "vlan",
+			iface:   &vlanInterface{logicalInterface{name: "testname", config: configMethodStatic{hwaddress: net.HardwareAddr([]byte{0, 1, 2, 3, 4, 5})}}, 1, ""},
+		},
+		{
+			name:    "testname",
+			netdev:  "[NetDev]\nKind=vlan\nName=testname\nMACAddress=00:01:02:03:04:05\n\n[VLAN]\nId=1\n",
+			network: "[Match]\nName=testname\n\n[Network]\nDHCP=true\n",
+			kind:    "vlan",
+			iface:   &vlanInterface{logicalInterface{name: "testname", config: configMethodDHCP{hwaddress: net.HardwareAddr([]byte{0, 1, 2, 3, 4, 5})}}, 1, ""},
+		},
+		{
+			name:    "testname",
+			netdev:  "[NetDev]\nKind=vlan\nName=testname\n\n[VLAN]\nId=0\n",
+			network: "[Match]\nName=testname\n\n[Network]\nDNS=8.8.8.8\n\n[Address]\nAddress=192.168.1.100/24\n\n[Route]\nDestination=0.0.0.0/0\nGateway=1.2.3.4\n",
+			kind:    "vlan",
+			iface: &vlanInterface{logicalInterface: logicalInterface{
+				name: "testname",
+				config: configMethodStatic{
+					addresses:   []net.IPNet{{IP: []byte{192, 168, 1, 100}, Mask: []byte{255, 255, 255, 0}}},
+					nameservers: []net.IP{[]byte{8, 8, 8, 8}},
+					routes:      []route{route{destination: net.IPNet{IP: []byte{0, 0, 0, 0}, Mask: []byte{0, 0, 0, 0}}, gateway: []byte{1, 2, 3, 4}}},
+				},
+			}},
+		},
+	} {
+		if name := tt.iface.Name(); name != tt.name {
+			t.Fatalf("bad name (%q): want %q, got %q", tt.iface, tt.name, name)
+		}
+		if netdev := tt.iface.Netdev(); netdev != tt.netdev {
+			t.Fatalf("bad netdev (%q): want %q, got %q", tt.iface, tt.netdev, netdev)
+		}
+		if link := tt.iface.Link(); link != tt.link {
+			t.Fatalf("bad link (%q): want %q, got %q", tt.iface, tt.link, link)
+		}
+		if network := tt.iface.Network(); network != tt.network {
+			t.Fatalf("bad network (%q): want %q, got %q", tt.iface, tt.network, network)
+		}
+		if kind := tt.iface.Type(); kind != tt.kind {
+			t.Fatalf("bad type (%q): want %q, got %q", tt.iface, tt.kind, kind)
+		}
+	}
+}
+
+func TestModprobeParams(t *testing.T) {
+	for _, tt := range []struct {
+		i InterfaceGenerator
+		p string
+	}{
+		{
+			i: &physicalInterface{},
+			p: "",
+		},
+		{
+			i: &vlanInterface{},
+			p: "",
+		},
+		{
+			i: &bondInterface{
+				logicalInterface{},
+				nil,
+				map[string]string{
+					"a": "1",
+					"b": "2",
+				},
+			},
+			p: "a=1 b=2",
+		},
+	} {
+		if p := tt.i.ModprobeParams(); p != tt.p {
+			t.Fatalf("bad params (%q): got %s, want %s", tt.i, p, tt.p)
+		}
+	}
+}
+
+func TestBuildInterfacesLo(t *testing.T) {
+	stanzas := []*stanzaInterface{
+		&stanzaInterface{
+			name:         "lo",
+			kind:         interfacePhysical,
+			auto:         false,
+			configMethod: configMethodLoopback{},
+			options:      map[string][]string{},
+		},
+	}
+	interfaces := buildInterfaces(stanzas)
+	if len(interfaces) != 0 {
+		t.FailNow()
+	}
+}
+
+func TestBuildInterfacesBlindBond(t *testing.T) {
+	stanzas := []*stanzaInterface{
+		{
+			name:         "bond0",
+			kind:         interfaceBond,
+			auto:         false,
+			configMethod: configMethodManual{},
+			options: map[string][]string{
+				"bond-slaves": []string{"eth0"},
+			},
+		},
+	}
+	interfaces := buildInterfaces(stanzas)
+	bond0 := &bondInterface{
+		logicalInterface{
+			name:        "bond0",
+			config:      configMethodManual{},
+			children:    []networkInterface{},
+			configDepth: 0,
+		},
+		[]string{"eth0"},
+		map[string]string{},
+	}
+	eth0 := &physicalInterface{
+		logicalInterface{
+			name:        "eth0",
+			config:      configMethodManual{},
+			children:    []networkInterface{bond0},
+			configDepth: 1,
+		},
+	}
+	expect := []InterfaceGenerator{bond0, eth0}
+	if !reflect.DeepEqual(interfaces, expect) {
+		t.FailNow()
+	}
+}
+
+func TestBuildInterfacesBlindVLAN(t *testing.T) {
+	stanzas := []*stanzaInterface{
+		{
+			name:         "vlan0",
+			kind:         interfaceVLAN,
+			auto:         false,
+			configMethod: configMethodManual{},
+			options: map[string][]string{
+				"id":         []string{"0"},
+				"raw_device": []string{"eth0"},
+			},
+		},
+	}
+	interfaces := buildInterfaces(stanzas)
+	vlan0 := &vlanInterface{
+		logicalInterface{
+			name:        "vlan0",
+			config:      configMethodManual{},
+			children:    []networkInterface{},
+			configDepth: 0,
+		},
+		0,
+		"eth0",
+	}
+	eth0 := &physicalInterface{
+		logicalInterface{
+			name:        "eth0",
+			config:      configMethodManual{},
+			children:    []networkInterface{vlan0},
+			configDepth: 1,
+		},
+	}
+	expect := []InterfaceGenerator{eth0, vlan0}
+	if !reflect.DeepEqual(interfaces, expect) {
+		t.FailNow()
+	}
+}
+
+func TestBuildInterfaces(t *testing.T) {
+	stanzas := []*stanzaInterface{
+		&stanzaInterface{
+			name:         "eth0",
+			kind:         interfacePhysical,
+			auto:         false,
+			configMethod: configMethodManual{},
+			options:      map[string][]string{},
+		},
+		&stanzaInterface{
+			name:         "bond0",
+			kind:         interfaceBond,
+			auto:         false,
+			configMethod: configMethodManual{},
+			options: map[string][]string{
+				"bond-slaves": []string{"eth0"},
+				"bond-mode":   []string{"4"},
+				"bond-miimon": []string{"100"},
+			},
+		},
+		&stanzaInterface{
+			name:         "bond1",
+			kind:         interfaceBond,
+			auto:         false,
+			configMethod: configMethodManual{},
+			options: map[string][]string{
+				"bond-slaves": []string{"bond0"},
+			},
+		},
+		&stanzaInterface{
+			name:         "vlan0",
+			kind:         interfaceVLAN,
+			auto:         false,
+			configMethod: configMethodManual{},
+			options: map[string][]string{
+				"id":         []string{"0"},
+				"raw_device": []string{"eth0"},
+			},
+		},
+		&stanzaInterface{
+			name:         "vlan1",
+			kind:         interfaceVLAN,
+			auto:         false,
+			configMethod: configMethodManual{},
+			options: map[string][]string{
+				"id":         []string{"1"},
+				"raw_device": []string{"bond0"},
+			},
+		},
+	}
+	interfaces := buildInterfaces(stanzas)
+	vlan1 := &vlanInterface{
+		logicalInterface{
+			name:        "vlan1",
+			config:      configMethodManual{},
+			children:    []networkInterface{},
+			configDepth: 0,
+		},
+		1,
+		"bond0",
+	}
+	vlan0 := &vlanInterface{
+		logicalInterface{
+			name:        "vlan0",
+			config:      configMethodManual{},
+			children:    []networkInterface{},
+			configDepth: 0,
+		},
+		0,
+		"eth0",
+	}
+	bond1 := &bondInterface{
+		logicalInterface{
+			name:        "bond1",
+			config:      configMethodManual{},
+			children:    []networkInterface{},
+			configDepth: 0,
+		},
+		[]string{"bond0"},
+		map[string]string{},
+	}
+	bond0 := &bondInterface{
+		logicalInterface{
+			name:        "bond0",
+			config:      configMethodManual{},
+			children:    []networkInterface{bond1, vlan1},
+			configDepth: 1,
+		},
+		[]string{"eth0"},
+		map[string]string{
+			"mode":   "4",
+			"miimon": "100",
+		},
+	}
+	eth0 := &physicalInterface{
+		logicalInterface{
+			name:        "eth0",
+			config:      configMethodManual{},
+			children:    []networkInterface{bond0, vlan0},
+			configDepth: 2,
+		},
+	}
+	expect := []InterfaceGenerator{bond0, bond1, eth0, vlan0, vlan1}
+	if !reflect.DeepEqual(interfaces, expect) {
+		t.FailNow()
+	}
+}
+
+func TestFilename(t *testing.T) {
+	for _, tt := range []struct {
+		i logicalInterface
+		f string
+	}{
+		{logicalInterface{name: "iface", configDepth: 0}, "00-iface"},
+		{logicalInterface{name: "iface", configDepth: 9}, "09-iface"},
+		{logicalInterface{name: "iface", configDepth: 10}, "0a-iface"},
+		{logicalInterface{name: "iface", configDepth: 53}, "35-iface"},
+		{logicalInterface{hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}), configDepth: 1}, "01-01:23:45:67:89:ab"},
+		{logicalInterface{name: "iface", hwaddr: net.HardwareAddr([]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab}), configDepth: 1}, "01-iface"},
+	} {
+		if tt.i.Filename() != tt.f {
+			t.Fatalf("bad filename (%q): got %q, want %q", tt.i, tt.i.Filename(), tt.f)
+		}
+	}
+}
--- a/network/stanza.go
+++ b/network/stanza.go
@@ -0,0 +1,326 @@
+package network
+
+import (
+	"fmt"
+	"net"
+	"strconv"
+	"strings"
+)
+
+type stanza interface{}
+
+type stanzaAuto struct {
+	interfaces []string
+}
+
+type stanzaInterface struct {
+	name         string
+	kind         interfaceKind
+	auto         bool
+	configMethod configMethod
+	options      map[string][]string
+}
+
+type interfaceKind int
+
+const (
+	interfaceBond = interfaceKind(iota)
+	interfacePhysical
+	interfaceVLAN
+)
+
+type route struct {
+	destination net.IPNet
+	gateway     net.IP
+}
+
+type configMethod interface{}
+
+type configMethodStatic struct {
+	addresses   []net.IPNet
+	nameservers []net.IP
+	routes      []route
+	hwaddress   net.HardwareAddr
+}
+
+type configMethodLoopback struct{}
+
+type configMethodManual struct{}
+
+type configMethodDHCP struct {
+	hwaddress net.HardwareAddr
+}
+
+func parseStanzas(lines []string) (stanzas []stanza, err error) {
+	rawStanzas, err := splitStanzas(lines)
+	if err != nil {
+		return nil, err
+	}
+
+	stanzas = make([]stanza, 0, len(rawStanzas))
+	for _, rawStanza := range rawStanzas {
+		if stanza, err := parseStanza(rawStanza); err == nil {
+			stanzas = append(stanzas, stanza)
+		} else {
+			return nil, err
+		}
+	}
+
+	autos := make([]string, 0)
+	interfaceMap := make(map[string]*stanzaInterface)
+	for _, stanza := range stanzas {
+		switch c := stanza.(type) {
+		case *stanzaAuto:
+			autos = append(autos, c.interfaces...)
+		case *stanzaInterface:
+			interfaceMap[c.name] = c
+		}
+	}
+
+	// Apply the auto attribute
+	for _, auto := range autos {
+		if iface, ok := interfaceMap[auto]; ok {
+			iface.auto = true
+		}
+	}
+
+	return stanzas, nil
+}
+
+func splitStanzas(lines []string) ([][]string, error) {
+	var curStanza []string
+	stanzas := make([][]string, 0)
+	for _, line := range lines {
+		if isStanzaStart(line) {
+			if curStanza != nil {
+				stanzas = append(stanzas, curStanza)
+			}
+			curStanza = []string{line}
+		} else if curStanza != nil {
+			curStanza = append(curStanza, line)
+		} else {
+			return nil, fmt.Errorf("missing stanza start %q", line)
+		}
+	}
+
+	if curStanza != nil {
+		stanzas = append(stanzas, curStanza)
+	}
+
+	return stanzas, nil
+}
+
+func isStanzaStart(line string) bool {
+	switch strings.Split(line, " ")[0] {
+	case "auto":
+		fallthrough
+	case "iface":
+		fallthrough
+	case "mapping":
+		return true
+	}
+
+	if strings.HasPrefix(line, "allow-") {
+		return true
+	}
+
+	return false
+}
+
+func parseStanza(rawStanza []string) (stanza, error) {
+	if len(rawStanza) == 0 {
+		panic("empty stanza")
+	}
+	tokens := strings.Fields(rawStanza[0])
+	if len(tokens) < 2 {
+		return nil, fmt.Errorf("malformed stanza start %q", rawStanza[0])
+	}
+
+	kind := tokens[0]
+	attributes := tokens[1:]
+
+	switch kind {
+	case "auto":
+		return parseAutoStanza(attributes, rawStanza[1:])
+	case "iface":
+		return parseInterfaceStanza(attributes, rawStanza[1:])
+	default:
+		return nil, fmt.Errorf("unknown stanza %q", kind)
+	}
+}
+
+func parseAutoStanza(attributes []string, options []string) (*stanzaAuto, error) {
+	return &stanzaAuto{interfaces: attributes}, nil
+}
+
+func parseInterfaceStanza(attributes []string, options []string) (*stanzaInterface, error) {
+	if len(attributes) != 3 {
+		return nil, fmt.Errorf("incorrect number of attributes")
+	}
+
+	iface := attributes[0]
+	confMethod := attributes[2]
+
+	optionMap := make(map[string][]string, 0)
+	for _, option := range options {
+		if strings.HasPrefix(option, "post-up") {
+			tokens := strings.SplitAfterN(option, " ", 2)
+			if len(tokens) != 2 {
+				continue
+			}
+			if v, ok := optionMap["post-up"]; ok {
+				optionMap["post-up"] = append(v, tokens[1])
+			} else {
+				optionMap["post-up"] = []string{tokens[1]}
+			}
+		} else if strings.HasPrefix(option, "pre-down") {
+			tokens := strings.SplitAfterN(option, " ", 2)
+			if len(tokens) != 2 {
+				continue
+			}
+			if v, ok := optionMap["pre-down"]; ok {
+				optionMap["pre-down"] = append(v, tokens[1])
+			} else {
+				optionMap["pre-down"] = []string{tokens[1]}
+			}
+		} else {
+			tokens := strings.Fields(option)
+			optionMap[tokens[0]] = tokens[1:]
+		}
+	}
+
+	var conf configMethod
+	switch confMethod {
+	case "static":
+		config := configMethodStatic{
+			addresses:   make([]net.IPNet, 1),
+			routes:      make([]route, 0),
+			nameservers: make([]net.IP, 0),
+		}
+		if addresses, ok := optionMap["address"]; ok {
+			if len(addresses) == 1 {
+				config.addresses[0].IP = net.ParseIP(addresses[0])
+			}
+		}
+		if netmasks, ok := optionMap["netmask"]; ok {
+			if len(netmasks) == 1 {
+				config.addresses[0].Mask = net.IPMask(net.ParseIP(netmasks[0]).To4())
+			}
+		}
+		if config.addresses[0].IP == nil || config.addresses[0].Mask == nil {
+			return nil, fmt.Errorf("malformed static network config for %q", iface)
+		}
+		if gateways, ok := optionMap["gateway"]; ok {
+			if len(gateways) == 1 {
+				config.routes = append(config.routes, route{
+					destination: net.IPNet{
+						IP:   net.IPv4(0, 0, 0, 0),
+						Mask: net.IPv4Mask(0, 0, 0, 0),
+					},
+					gateway: net.ParseIP(gateways[0]),
+				})
+			}
+		}
+		if hwaddress, err := parseHwaddress(optionMap, iface); err == nil {
+			config.hwaddress = hwaddress
+		} else {
+			return nil, err
+		}
+		for _, nameserver := range optionMap["dns-nameservers"] {
+			config.nameservers = append(config.nameservers, net.ParseIP(nameserver))
+		}
+		for _, postup := range optionMap["post-up"] {
+			if strings.HasPrefix(postup, "route add") {
+				route := route{}
+				fields := strings.Fields(postup)
+				for i, field := range fields[:len(fields)-1] {
+					switch field {
+					case "-net":
+						if _, dst, err := net.ParseCIDR(fields[i+1]); err == nil {
+							route.destination = *dst
+						} else {
+							route.destination.IP = net.ParseIP(fields[i+1])
+						}
+					case "netmask":
+						route.destination.Mask = net.IPMask(net.ParseIP(fields[i+1]).To4())
+					case "gw":
+						route.gateway = net.ParseIP(fields[i+1])
+					}
+				}
+				if route.destination.IP != nil && route.destination.Mask != nil && route.gateway != nil {
+					config.routes = append(config.routes, route)
+				}
+			}
+		}
+		conf = config
+	case "loopback":
+		conf = configMethodLoopback{}
+	case "manual":
+		conf = configMethodManual{}
+	case "dhcp":
+		config := configMethodDHCP{}
+		if hwaddress, err := parseHwaddress(optionMap, iface); err == nil {
+			config.hwaddress = hwaddress
+		} else {
+			return nil, err
+		}
+		conf = config
+	default:
+		return nil, fmt.Errorf("invalid config method %q", confMethod)
+	}
+
+	if _, ok := optionMap["vlan_raw_device"]; ok {
+		return parseVLANStanza(iface, conf, attributes, optionMap)
+	}
+
+	if strings.Contains(iface, ".") {
+		return parseVLANStanza(iface, conf, attributes, optionMap)
+	}
+
+	if _, ok := optionMap["bond-slaves"]; ok {
+		return parseBondStanza(iface, conf, attributes, optionMap)
+	}
+
+	return parsePhysicalStanza(iface, conf, attributes, optionMap)
+}
+
+func parseHwaddress(options map[string][]string, iface string) (net.HardwareAddr, error) {
+	if hwaddress, ok := options["hwaddress"]; ok && len(hwaddress) == 2 {
+		switch hwaddress[0] {
+		case "ether":
+			if address, err := net.ParseMAC(hwaddress[1]); err == nil {
+				return address, nil
+			}
+			return nil, fmt.Errorf("malformed hwaddress option for %q", iface)
+		}
+	}
+	return nil, nil
+}
+
+func parseBondStanza(iface string, conf configMethod, attributes []string, options map[string][]string) (*stanzaInterface, error) {
+	return &stanzaInterface{name: iface, kind: interfaceBond, configMethod: conf, options: options}, nil
+}
+
+func parsePhysicalStanza(iface string, conf configMethod, attributes []string, options map[string][]string) (*stanzaInterface, error) {
+	return &stanzaInterface{name: iface, kind: interfacePhysical, configMethod: conf, options: options}, nil
+}
+
+func parseVLANStanza(iface string, conf configMethod, attributes []string, options map[string][]string) (*stanzaInterface, error) {
+	var id string
+	if strings.Contains(iface, ".") {
+		tokens := strings.Split(iface, ".")
+		id = tokens[len(tokens)-1]
+	} else if strings.HasPrefix(iface, "vlan") {
+		id = strings.TrimPrefix(iface, "vlan")
+	} else {
+		return nil, fmt.Errorf("malformed vlan name %q", iface)
+	}
+
+	if _, err := strconv.Atoi(id); err != nil {
+		return nil, fmt.Errorf("malformed vlan name %q", iface)
+	}
+	options["id"] = []string{id}
+	options["raw_device"] = options["vlan_raw_device"]
+
+	return &stanzaInterface{name: iface, kind: interfaceVLAN, configMethod: conf, options: options}, nil
+}
--- a/network/stanza_test.go
+++ b/network/stanza_test.go
@@ -0,0 +1,568 @@
+package network
+
+import (
+	"net"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestSplitStanzasNoParent(t *testing.T) {
+	in := []string{"test"}
+	e := "missing stanza start"
+	_, err := splitStanzas(in)
+	if err == nil || !strings.HasPrefix(err.Error(), e) {
+		t.Fatalf("bad error for splitStanzas(%q): got %q, want %q", in, err, e)
+	}
+}
+
+func TestBadParseStanzas(t *testing.T) {
+	for in, e := range map[string]string{
+		"":                 "missing stanza start",
+		"iface":            "malformed stanza start",
+		"allow-?? unknown": "unknown stanza",
+	} {
+		_, err := parseStanzas([]string{in})
+		if err == nil || !strings.HasPrefix(err.Error(), e) {
+			t.Fatalf("bad error for parseStanzas(%q): got %q, want %q", in, err, e)
+		}
+
+	}
+}
+
+func TestBadParseInterfaceStanza(t *testing.T) {
+	for _, tt := range []struct {
+		in   []string
+		opts []string
+		e    string
+	}{
+		{[]string{}, nil, "incorrect number of attributes"},
+		{[]string{"eth", "inet", "invalid"}, nil, "invalid config method"},
+		{[]string{"eth", "inet", "static"}, []string{"address 192.168.1.100"}, "malformed static network config"},
+		{[]string{"eth", "inet", "static"}, []string{"netmask 255.255.255.0"}, "malformed static network config"},
+		{[]string{"eth", "inet", "static"}, []string{"address invalid", "netmask 255.255.255.0"}, "malformed static network config"},
+		{[]string{"eth", "inet", "static"}, []string{"address 192.168.1.100", "netmask invalid"}, "malformed static network config"},
+		{[]string{"eth", "inet", "static"}, []string{"address 192.168.1.100", "netmask 255.255.255.0", "hwaddress ether NotAnAddress"}, "malformed hwaddress option"},
+		{[]string{"eth", "inet", "dhcp"}, []string{"hwaddress ether NotAnAddress"}, "malformed hwaddress option"},
+	} {
+		_, err := parseInterfaceStanza(tt.in, tt.opts)
+		if err == nil || !strings.HasPrefix(err.Error(), tt.e) {
+			t.Fatalf("bad error parsing interface stanza %q: got %q, want %q", tt.in, err.Error(), tt.e)
+		}
+	}
+}
+
+func TestBadParseVLANStanzas(t *testing.T) {
+	conf := configMethodManual{}
+	options := map[string][]string{}
+	for _, in := range []string{"myvlan", "eth.vlan"} {
+		_, err := parseVLANStanza(in, conf, nil, options)
+		if err == nil || !strings.HasPrefix(err.Error(), "malformed vlan name") {
+			t.Fatalf("did not error on bad vlan %q", in)
+		}
+	}
+}
+
+func TestSplitStanzas(t *testing.T) {
+	expect := [][]string{
+		{"auto lo"},
+		{"iface eth1", "option: 1"},
+		{"mapping"},
+		{"allow-"},
+	}
+	lines := make([]string, 0, 5)
+	for _, stanza := range expect {
+		for _, line := range stanza {
+			lines = append(lines, line)
+		}
+	}
+
+	stanzas, err := splitStanzas(lines)
+	if err != nil {
+		t.FailNow()
+	}
+	for i, stanza := range stanzas {
+		if len(stanza) != len(expect[i]) {
+			t.FailNow()
+		}
+		for j, line := range stanza {
+			if line != expect[i][j] {
+				t.FailNow()
+			}
+		}
+	}
+}
+
+func TestParseStanzaNil(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Fatal("parseStanza(nil) did not panic")
+		}
+	}()
+	parseStanza(nil)
+}
+
+func TestParseStanzaSuccess(t *testing.T) {
+	for _, in := range []string{
+		"auto a",
+		"iface a inet manual",
+	} {
+		if _, err := parseStanza([]string{in}); err != nil {
+			t.Fatalf("unexpected error parsing stanza %q: %s", in, err)
+		}
+	}
+}
+
+func TestParseAutoStanza(t *testing.T) {
+	interfaces := []string{"test", "attribute"}
+	stanza, err := parseAutoStanza(interfaces, nil)
+	if err != nil {
+		t.Fatalf("unexpected error parsing auto stanza %q: %s", interfaces, err)
+	}
+	if !reflect.DeepEqual(stanza.interfaces, interfaces) {
+		t.FailNow()
+	}
+}
+
+func TestParseBondStanzaNoSlaves(t *testing.T) {
+	bond, err := parseBondStanza("", nil, nil, map[string][]string{})
+	if err != nil {
+		t.FailNow()
+	}
+	if bond.options["bond-slaves"] != nil {
+		t.FailNow()
+	}
+}
+
+func TestParseBondStanza(t *testing.T) {
+	conf := configMethodManual{}
+	options := map[string][]string{
+		"bond-slaves": []string{"1", "2"},
+	}
+	bond, err := parseBondStanza("test", conf, nil, options)
+	if err != nil {
+		t.FailNow()
+	}
+	if bond.name != "test" {
+		t.FailNow()
+	}
+	if bond.kind != interfaceBond {
+		t.FailNow()
+	}
+	if bond.configMethod != conf {
+		t.FailNow()
+	}
+}
+
+func TestParsePhysicalStanza(t *testing.T) {
+	conf := configMethodManual{}
+	options := map[string][]string{
+		"a": []string{"1", "2"},
+		"b": []string{"1"},
+	}
+	physical, err := parsePhysicalStanza("test", conf, nil, options)
+	if err != nil {
+		t.FailNow()
+	}
+	if physical.name != "test" {
+		t.FailNow()
+	}
+	if physical.kind != interfacePhysical {
+		t.FailNow()
+	}
+	if physical.configMethod != conf {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(physical.options, options) {
+		t.FailNow()
+	}
+}
+
+func TestParseVLANStanzas(t *testing.T) {
+	conf := configMethodManual{}
+	options := map[string][]string{}
+	for _, in := range []string{"vlan25", "eth.25"} {
+		vlan, err := parseVLANStanza(in, conf, nil, options)
+		if err != nil {
+			t.Fatalf("unexpected error from parseVLANStanza(%q): %s", in, err)
+		}
+		if !reflect.DeepEqual(vlan.options["id"], []string{"25"}) {
+			t.FailNow()
+		}
+	}
+}
+
+func TestParseInterfaceStanzaStaticAddress(t *testing.T) {
+	options := []string{"address 192.168.1.100", "netmask 255.255.255.0"}
+	expect := []net.IPNet{
+		{
+			IP:   net.IPv4(192, 168, 1, 100),
+			Mask: net.IPv4Mask(255, 255, 255, 0),
+		},
+	}
+
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "static"}, options)
+	if err != nil {
+		t.FailNow()
+	}
+	static, ok := iface.configMethod.(configMethodStatic)
+	if !ok {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(static.addresses, expect) {
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaStaticGateway(t *testing.T) {
+	options := []string{"address 192.168.1.100", "netmask 255.255.255.0", "gateway 192.168.1.1"}
+	expect := []route{
+		{
+			destination: net.IPNet{
+				IP:   net.IPv4(0, 0, 0, 0),
+				Mask: net.IPv4Mask(0, 0, 0, 0),
+			},
+			gateway: net.IPv4(192, 168, 1, 1),
+		},
+	}
+
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "static"}, options)
+	if err != nil {
+		t.FailNow()
+	}
+	static, ok := iface.configMethod.(configMethodStatic)
+	if !ok {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(static.routes, expect) {
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaStaticDNS(t *testing.T) {
+	options := []string{"address 192.168.1.100", "netmask 255.255.255.0", "dns-nameservers 192.168.1.10 192.168.1.11 192.168.1.12"}
+	expect := []net.IP{
+		net.IPv4(192, 168, 1, 10),
+		net.IPv4(192, 168, 1, 11),
+		net.IPv4(192, 168, 1, 12),
+	}
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "static"}, options)
+	if err != nil {
+		t.FailNow()
+	}
+	static, ok := iface.configMethod.(configMethodStatic)
+	if !ok {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(static.nameservers, expect) {
+		t.FailNow()
+	}
+}
+
+func TestBadParseInterfaceStanzasStaticPostUp(t *testing.T) {
+	for _, in := range []string{
+		"post-up invalid",
+		"post-up route add",
+		"post-up route add -net",
+		"post-up route add gw",
+		"post-up route add netmask",
+		"gateway",
+		"gateway 192.168.1.1 192.168.1.2",
+	} {
+		options := []string{"address 192.168.1.100", "netmask 255.255.255.0", in}
+		iface, err := parseInterfaceStanza([]string{"eth", "inet", "static"}, options)
+		if err != nil {
+			t.Fatalf("parseInterfaceStanza with options %s got unexpected error", options)
+		}
+		static, ok := iface.configMethod.(configMethodStatic)
+		if !ok {
+			t.Fatalf("parseInterfaceStanza with options %s did not return configMethodStatic", options)
+		}
+		if len(static.routes) != 0 {
+			t.Fatalf("parseInterfaceStanza with options %s did not return zero-length static routes", options)
+		}
+	}
+}
+
+func TestParseInterfaceStanzaStaticPostUp(t *testing.T) {
+	for _, tt := range []struct {
+		options []string
+		expect  []route
+	}{
+		{
+			options: []string{
+				"address 192.168.1.100",
+				"netmask 255.255.255.0",
+				"post-up route add gw 192.168.1.1 -net 192.168.1.0 netmask 255.255.255.0",
+			},
+			expect: []route{
+				{
+					destination: net.IPNet{
+						IP:   net.IPv4(192, 168, 1, 0),
+						Mask: net.IPv4Mask(255, 255, 255, 0),
+					},
+					gateway: net.IPv4(192, 168, 1, 1),
+				},
+			},
+		},
+		{
+			options: []string{
+				"address 192.168.1.100",
+				"netmask 255.255.255.0",
+				"post-up route add gw 192.168.1.1 -net 192.168.1.0/24 || true",
+			},
+			expect: []route{
+				{
+					destination: func() net.IPNet {
+						if _, net, err := net.ParseCIDR("192.168.1.0/24"); err == nil {
+							return *net
+						} else {
+							panic(err)
+						}
+					}(),
+					gateway: net.IPv4(192, 168, 1, 1),
+				},
+			},
+		},
+	} {
+		iface, err := parseInterfaceStanza([]string{"eth", "inet", "static"}, tt.options)
+		if err != nil {
+			t.Fatalf("bad error (%+v): want nil, got %s\n", tt, err)
+		}
+		static, ok := iface.configMethod.(configMethodStatic)
+		if !ok {
+			t.Fatalf("bad config method (%+v): want configMethodStatic, got %T\n", tt, iface.configMethod)
+		}
+		if !reflect.DeepEqual(static.routes, tt.expect) {
+			t.Fatalf("bad routes (%+v): want %#v, got %#v\n", tt, tt.expect, static.routes)
+		}
+	}
+}
+
+func TestParseInterfaceStanzaLoopback(t *testing.T) {
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "loopback"}, nil)
+	if err != nil {
+		t.FailNow()
+	}
+	if _, ok := iface.configMethod.(configMethodLoopback); !ok {
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaManual(t *testing.T) {
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "manual"}, nil)
+	if err != nil {
+		t.FailNow()
+	}
+	if _, ok := iface.configMethod.(configMethodManual); !ok {
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaDHCP(t *testing.T) {
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "dhcp"}, nil)
+	if err != nil {
+		t.FailNow()
+	}
+	if _, ok := iface.configMethod.(configMethodDHCP); !ok {
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaPostUpOption(t *testing.T) {
+	options := []string{
+		"post-up",
+		"post-up 1 2",
+		"post-up 3 4",
+	}
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "manual"}, options)
+	if err != nil {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(iface.options["post-up"], []string{"1 2", "3 4"}) {
+		t.Log(iface.options["post-up"])
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaPreDownOption(t *testing.T) {
+	options := []string{
+		"pre-down",
+		"pre-down 3",
+		"pre-down 4",
+	}
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "manual"}, options)
+	if err != nil {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(iface.options["pre-down"], []string{"3", "4"}) {
+		t.Log(iface.options["pre-down"])
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaEmptyOption(t *testing.T) {
+	options := []string{
+		"test",
+	}
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "manual"}, options)
+	if err != nil {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(iface.options["test"], []string{}) {
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaOptions(t *testing.T) {
+	options := []string{
+		"test1 1",
+		"test2 2 3",
+		"test1 5 6",
+	}
+	iface, err := parseInterfaceStanza([]string{"eth", "inet", "manual"}, options)
+	if err != nil {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(iface.options["test1"], []string{"5", "6"}) {
+		t.Log(iface.options["test1"])
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(iface.options["test2"], []string{"2", "3"}) {
+		t.Log(iface.options["test2"])
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaHwaddress(t *testing.T) {
+	for _, tt := range []struct {
+		attr []string
+		opt  []string
+		hw   net.HardwareAddr
+	}{
+		{
+			[]string{"mybond", "inet", "dhcp"},
+			[]string{},
+			nil,
+		},
+		{
+			[]string{"mybond", "inet", "dhcp"},
+			[]string{"hwaddress ether 00:01:02:03:04:05"},
+			net.HardwareAddr([]byte{0, 1, 2, 3, 4, 5}),
+		},
+		{
+			[]string{"mybond", "inet", "static"},
+			[]string{"hwaddress ether 00:01:02:03:04:05", "address 192.168.1.100", "netmask 255.255.255.0"},
+			net.HardwareAddr([]byte{0, 1, 2, 3, 4, 5}),
+		},
+	} {
+		iface, err := parseInterfaceStanza(tt.attr, tt.opt)
+		if err != nil {
+			t.Fatalf("error in parseInterfaceStanza (%q, %q): %q", tt.attr, tt.opt, err)
+		}
+		switch c := iface.configMethod.(type) {
+		case configMethodStatic:
+			if !reflect.DeepEqual(c.hwaddress, tt.hw) {
+				t.Fatalf("bad hwaddress (%q, %q): got %q, want %q", tt.attr, tt.opt, c.hwaddress, tt.hw)
+			}
+		case configMethodDHCP:
+			if !reflect.DeepEqual(c.hwaddress, tt.hw) {
+				t.Fatalf("bad hwaddress (%q, %q): got %q, want %q", tt.attr, tt.opt, c.hwaddress, tt.hw)
+			}
+		}
+	}
+}
+
+func TestParseInterfaceStanzaBond(t *testing.T) {
+	iface, err := parseInterfaceStanza([]string{"mybond", "inet", "manual"}, []string{"bond-slaves eth"})
+	if err != nil {
+		t.FailNow()
+	}
+	if iface.kind != interfaceBond {
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaVLANName(t *testing.T) {
+	iface, err := parseInterfaceStanza([]string{"eth0.1", "inet", "manual"}, nil)
+	if err != nil {
+		t.FailNow()
+	}
+	if iface.kind != interfaceVLAN {
+		t.FailNow()
+	}
+}
+
+func TestParseInterfaceStanzaVLANOption(t *testing.T) {
+	iface, err := parseInterfaceStanza([]string{"vlan1", "inet", "manual"}, []string{"vlan_raw_device eth"})
+	if err != nil {
+		t.FailNow()
+	}
+	if iface.kind != interfaceVLAN {
+		t.FailNow()
+	}
+}
+
+func TestParseStanzasNone(t *testing.T) {
+	stanzas, err := parseStanzas(nil)
+	if err != nil {
+		t.FailNow()
+	}
+	if len(stanzas) != 0 {
+		t.FailNow()
+	}
+}
+
+func TestParseStanzas(t *testing.T) {
+	lines := []string{
+		"auto lo",
+		"iface lo inet loopback",
+		"iface eth1 inet manual",
+		"iface eth2 inet manual",
+		"iface eth3 inet manual",
+		"auto eth1 eth3",
+	}
+	expect := []stanza{
+		&stanzaAuto{
+			interfaces: []string{"lo"},
+		},
+		&stanzaInterface{
+			name:         "lo",
+			kind:         interfacePhysical,
+			auto:         true,
+			configMethod: configMethodLoopback{},
+			options:      map[string][]string{},
+		},
+		&stanzaInterface{
+			name:         "eth1",
+			kind:         interfacePhysical,
+			auto:         true,
+			configMethod: configMethodManual{},
+			options:      map[string][]string{},
+		},
+		&stanzaInterface{
+			name:         "eth2",
+			kind:         interfacePhysical,
+			auto:         false,
+			configMethod: configMethodManual{},
+			options:      map[string][]string{},
+		},
+		&stanzaInterface{
+			name:         "eth3",
+			kind:         interfacePhysical,
+			auto:         true,
+			configMethod: configMethodManual{},
+			options:      map[string][]string{},
+		},
+		&stanzaAuto{
+			interfaces: []string{"eth1", "eth3"},
+		},
+	}
+	stanzas, err := parseStanzas(lines)
+	if err != err {
+		t.FailNow()
+	}
+	if !reflect.DeepEqual(stanzas, expect) {
+		t.FailNow()
+	}
+}
--- a/pkg/http_client.go
+++ b/pkg/http_client.go
@@ -0,0 +1,161 @@
+package pkg
+
+import (
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/http"
+	neturl "net/url"
+	"strings"
+	"time"
+)
+
+const (
+	HTTP_2xx = 2
+	HTTP_4xx = 4
+)
+
+type Err error
+
+type ErrTimeout struct {
+	Err
+}
+
+type ErrNotFound struct {
+	Err
+}
+
+type ErrInvalid struct {
+	Err
+}
+
+type ErrServer struct {
+	Err
+}
+
+type ErrNetwork struct {
+	Err
+}
+
+type HttpClient struct {
+	// Maximum exp backoff duration. Defaults to 5 seconds
+	MaxBackoff time.Duration
+
+	// Maximum number of connection retries. Defaults to 15
+	MaxRetries int
+
+	// HTTP client timeout, this is suggested to be low since exponential
+	// backoff will kick off too. Defaults to 2 seconds
+	Timeout time.Duration
+
+	// Whether or not to skip TLS verification. Defaults to false
+	SkipTLS bool
+
+	client *http.Client
+}
+
+type Getter interface {
+	Get(string) ([]byte, error)
+	GetRetry(string) ([]byte, error)
+}
+
+func NewHttpClient() *HttpClient {
+	hc := &HttpClient{
+		MaxBackoff: time.Second * 5,
+		MaxRetries: 15,
+		Timeout:    time.Duration(2) * time.Second,
+		SkipTLS:    false,
+	}
+
+	// We need to create our own client in order to add timeout support.
+	// TODO(c4milo) Replace it once Go 1.3 is officially used by CoreOS
+	// More info: https://code.google.com/p/go/source/detail?r=ada6f2d5f99f
+	hc.client = &http.Client{
+		Transport: &http.Transport{
+			TLSClientConfig: &tls.Config{
+				InsecureSkipVerify: hc.SkipTLS,
+			},
+			Dial: func(network, addr string) (net.Conn, error) {
+				deadline := time.Now().Add(hc.Timeout)
+				c, err := net.DialTimeout(network, addr, hc.Timeout)
+				if err != nil {
+					return nil, err
+				}
+				c.SetDeadline(deadline)
+				return c, nil
+			},
+		},
+	}
+
+	return hc
+}
+
+func ExpBackoff(interval, max time.Duration) time.Duration {
+	interval = interval * 2
+	if interval > max {
+		interval = max
+	}
+	return interval
+}
+
+// GetRetry fetches a given URL with support for exponential backoff and maximum retries
+func (h *HttpClient) GetRetry(rawurl string) ([]byte, error) {
+	if rawurl == "" {
+		return nil, ErrInvalid{errors.New("URL is empty. Skipping.")}
+	}
+
+	url, err := neturl.Parse(rawurl)
+	if err != nil {
+		return nil, ErrInvalid{err}
+	}
+
+	// Unfortunately, url.Parse is too generic to throw errors if a URL does not
+	// have a valid HTTP scheme. So, we have to do this extra validation
+	if !strings.HasPrefix(url.Scheme, "http") {
+		return nil, ErrInvalid{fmt.Errorf("URL %s does not have a valid HTTP scheme. Skipping.", rawurl)}
+	}
+
+	dataURL := url.String()
+
+	duration := 50 * time.Millisecond
+	for retry := 1; retry <= h.MaxRetries; retry++ {
+		log.Printf("Fetching data from %s. Attempt #%d", dataURL, retry)
+
+		data, err := h.Get(dataURL)
+		switch err.(type) {
+		case ErrNetwork:
+			log.Printf(err.Error())
+		case ErrServer:
+			log.Printf(err.Error())
+		case ErrNotFound:
+			return data, err
+		default:
+			return data, err
+		}
+
+		duration = ExpBackoff(duration, h.MaxBackoff)
+		log.Printf("Sleeping for %v...", duration)
+		time.Sleep(duration)
+	}
+
+	return nil, ErrTimeout{fmt.Errorf("Unable to fetch data. Maximum retries reached: %d", h.MaxRetries)}
+}
+
+func (h *HttpClient) Get(dataURL string) ([]byte, error) {
+	if resp, err := h.client.Get(dataURL); err == nil {
+		defer resp.Body.Close()
+		switch resp.StatusCode / 100 {
+		case HTTP_2xx:
+			return ioutil.ReadAll(resp.Body)
+		case HTTP_4xx:
+			return nil, ErrNotFound{fmt.Errorf("Not found. HTTP status code: %d", resp.StatusCode)}
+		default:
+			return nil, ErrServer{fmt.Errorf("Server error. HTTP status code: %d", resp.StatusCode)}
+		}
+	} else {
+		return nil, ErrNetwork{fmt.Errorf("Unable to fetch data: %s", err.Error())}
+	}
+}
--- a/pkg/http_client_test.go
+++ b/pkg/http_client_test.go
@@ -0,0 +1,140 @@
+package pkg
+
+import (
+	"fmt"
+	"io"
+	"math"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+func TestExpBackoff(t *testing.T) {
+	duration := time.Millisecond
+	max := time.Hour
+	for i := 0; i < math.MaxUint16; i++ {
+		duration = ExpBackoff(duration, max)
+		if duration < 0 {
+			t.Fatalf("duration too small: %v %v", duration, i)
+		}
+		if duration > max {
+			t.Fatalf("duration too large: %v %v", duration, i)
+		}
+	}
+}
+
+// Test exponential backoff and that it continues retrying if a 5xx response is
+// received
+func TestGetURLExpBackOff(t *testing.T) {
+	var expBackoffTests = []struct {
+		count int
+		body  string
+	}{
+		{0, "number of attempts: 0"},
+		{1, "number of attempts: 1"},
+		{2, "number of attempts: 2"},
+	}
+	client := NewHttpClient()
+
+	for i, tt := range expBackoffTests {
+		mux := http.NewServeMux()
+		count := 0
+		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			if count == tt.count {
+				io.WriteString(w, fmt.Sprintf("number of attempts: %d", count))
+				return
+			}
+			count++
+			http.Error(w, "", 500)
+		})
+		ts := httptest.NewServer(mux)
+		defer ts.Close()
+
+		data, err := client.GetRetry(ts.URL)
+		if err != nil {
+			t.Errorf("Test case %d produced error: %v", i, err)
+		}
+
+		if count != tt.count {
+			t.Errorf("Test case %d failed: %d != %d", i, count, tt.count)
+		}
+
+		if string(data) != tt.body {
+			t.Errorf("Test case %d failed: %s != %s", i, tt.body, data)
+		}
+	}
+}
+
+// Test that it stops retrying if a 4xx response comes back
+func TestGetURL4xx(t *testing.T) {
+	client := NewHttpClient()
+	retries := 0
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		retries++
+		http.Error(w, "", 404)
+	}))
+	defer ts.Close()
+
+	_, err := client.GetRetry(ts.URL)
+	if err == nil {
+		t.Errorf("Incorrect result\ngot:  %s\nwant: %s", err.Error(), "Not found. HTTP status code: 404")
+	}
+
+	if retries > 1 {
+		t.Errorf("Number of retries:\n%d\nExpected number of retries:\n%s", retries, 1)
+	}
+}
+
+// Test that it fetches and returns user-data just fine
+func TestGetURL2xx(t *testing.T) {
+	var cloudcfg = `
+#cloud-config
+coreos: 
+	oem:
+	    id: test
+	    name: CoreOS.box for Test
+	    version-id: %VERSION_ID%+%BUILD_ID%
+	    home-url: https://github.com/coreos/coreos-cloudinit
+	    bug-report-url: https://github.com/coreos/coreos-cloudinit
+	update:
+		reboot-strategy: best-effort
+`
+
+	client := NewHttpClient()
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprint(w, cloudcfg)
+	}))
+	defer ts.Close()
+
+	data, err := client.GetRetry(ts.URL)
+	if err != nil {
+		t.Errorf("Incorrect result\ngot:  %v\nwant: %v", err, nil)
+	}
+
+	if string(data) != cloudcfg {
+		t.Errorf("Incorrect result\ngot:  %s\nwant: %s", string(data), cloudcfg)
+	}
+}
+
+// Test attempt to fetching using malformed URL
+func TestGetMalformedURL(t *testing.T) {
+	client := NewHttpClient()
+
+	var tests = []struct {
+		url  string
+		want string
+	}{
+		{"boo", "URL boo does not have a valid HTTP scheme. Skipping."},
+		{"mailto://boo", "URL mailto://boo does not have a valid HTTP scheme. Skipping."},
+		{"ftp://boo", "URL ftp://boo does not have a valid HTTP scheme. Skipping."},
+		{"", "URL is empty. Skipping."},
+	}
+
+	for _, test := range tests {
+		_, err := client.GetRetry(test.url)
+		if err == nil || err.Error() != test.want {
+			t.Errorf("Incorrect result\ngot:  %v\nwant: %v", err, test.want)
+		}
+	}
+}
--- a/src/github.com/coreos/coreos-cloudinit
+++ b/src/github.com/coreos/coreos-cloudinit
@@ -1 +0,0 @@
-../../../
--- a/system/env.go
+++ b/system/env.go
@@ -0,0 +1,26 @@
+package system
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// dropinContents generates the contents for a drop-in unit given the config.
+// The argument must be a struct from the 'config' package.
+func dropinContents(e interface{}) string {
+	et := reflect.TypeOf(e)
+	ev := reflect.ValueOf(e)
+
+	var out string
+	for i := 0; i < et.NumField(); i++ {
+		if val := ev.Field(i).String(); val != "" {
+			key := et.Field(i).Tag.Get("env")
+			out += fmt.Sprintf("Environment=\"%s=%s\"\n", key, val)
+		}
+	}
+
+	if out == "" {
+		return ""
+	}
+	return "[Service]\n" + out
+}
--- a/system/env_file.go
+++ b/system/env_file.go
@@ -0,0 +1,100 @@
+package system
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"regexp"
+	"sort"
+)
+
+type EnvFile struct {
+	Vars map[string]string
+	// mask File.Content, it shouldn't be used.
+	Content interface{} `json:"-" yaml:"-"`
+	*File
+}
+
+// only allow sh compatible identifiers
+var validKey = regexp.MustCompile(`^[a-zA-Z0-9_]+$`)
+
+// match each line, optionally capturing valid identifiers, discarding dos line endings
+var lineLexer = regexp.MustCompile(`(?m)^((?:([a-zA-Z0-9_]+)=)?.*?)\r?\n`)
+
+// mergeEnvContents: Update the existing file contents with new values,
+// preserving variable ordering and all content this code doesn't understand.
+// All new values are appended to the bottom of the old, sorted by key.
+func mergeEnvContents(old []byte, pending map[string]string) []byte {
+	var buf bytes.Buffer
+	var match [][]byte
+
+	// it is awkward for the regex to handle a missing newline gracefully
+	if len(old) != 0 && !bytes.HasSuffix(old, []byte{'\n'}) {
+		old = append(old, byte('\n'))
+	}
+
+	for _, match = range lineLexer.FindAllSubmatch(old, -1) {
+		key := string(match[2])
+		if value, ok := pending[key]; ok {
+			fmt.Fprintf(&buf, "%s=%s\n", key, value)
+			delete(pending, key)
+		} else {
+			fmt.Fprintf(&buf, "%s\n", match[1])
+		}
+	}
+
+	for _, key := range keys(pending) {
+		value := pending[key]
+		fmt.Fprintf(&buf, "%s=%s\n", key, value)
+	}
+
+	return buf.Bytes()
+}
+
+// WriteEnvFile updates an existing env `KEY=value` formated file with
+// new values provided in EnvFile.Vars; File.Content is ignored.
+// Existing ordering and any unknown formatting such as comments are
+// preserved. If no changes are required the file is untouched.
+func WriteEnvFile(ef *EnvFile, root string) error {
+	// validate new keys, mergeEnvContents uses pending to track writes
+	pending := make(map[string]string, len(ef.Vars))
+	for key, value := range ef.Vars {
+		if !validKey.MatchString(key) {
+			return fmt.Errorf("Invalid name %q for %s", key, ef.Path)
+		}
+		pending[key] = value
+	}
+
+	if len(pending) == 0 {
+		return nil
+	}
+
+	oldContent, err := ioutil.ReadFile(path.Join(root, ef.Path))
+	if err != nil {
+		if os.IsNotExist(err) {
+			oldContent = []byte{}
+		} else {
+			return err
+		}
+	}
+
+	newContent := mergeEnvContents(oldContent, pending)
+	if bytes.Equal(oldContent, newContent) {
+		return nil
+	}
+
+	ef.File.Content = string(newContent)
+	_, err = WriteFile(ef.File, root)
+	return err
+}
+
+// keys returns the keys of a map in sorted order
+func keys(m map[string]string) (s []string) {
+	for k, _ := range m {
+		s = append(s, k)
+	}
+	sort.Strings(s)
+	return
+}
--- a/system/env_file_test.go
+++ b/system/env_file_test.go
@@ -0,0 +1,428 @@
+package system
+
+import (
+	"io/ioutil"
+	"os"
+	"path"
+	"strings"
+	"syscall"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+const (
+	base          = "# a file\nFOO=base\n\nBAR= hi there\n"
+	baseNoNewline = "# a file\nFOO=base\n\nBAR= hi there"
+	baseDos       = "# a file\r\nFOO=base\r\n\r\nBAR= hi there\r\n"
+	expectUpdate  = "# a file\nFOO=test\n\nBAR= hi there\nNEW=a value\n"
+	expectCreate  = "FOO=test\nNEW=a value\n"
+)
+
+var (
+	valueUpdate = map[string]string{
+		"FOO": "test",
+		"NEW": "a value",
+	}
+	valueNoop = map[string]string{
+		"FOO": "base",
+	}
+	valueEmpty   = map[string]string{}
+	valueInvalid = map[string]string{
+		"FOO-X": "test",
+	}
+)
+
+func TestWriteEnvFileUpdate(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+	ioutil.WriteFile(fullPath, []byte(base), 0644)
+
+	oldStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueUpdate,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err != nil {
+		t.Fatalf("WriteFile failed: %v", err)
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != expectUpdate {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	}
+
+	newStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	if oldStat.Sys().(*syscall.Stat_t).Ino == newStat.Sys().(*syscall.Stat_t).Ino {
+		t.Fatalf("File was not replaced: %s", fullPath)
+	}
+}
+
+func TestWriteEnvFileUpdateNoNewline(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+	ioutil.WriteFile(fullPath, []byte(baseNoNewline), 0644)
+
+	oldStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueUpdate,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err != nil {
+		t.Fatalf("WriteFile failed: %v", err)
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != expectUpdate {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	}
+
+	newStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	if oldStat.Sys().(*syscall.Stat_t).Ino == newStat.Sys().(*syscall.Stat_t).Ino {
+		t.Fatalf("File was not replaced: %s", fullPath)
+	}
+}
+
+func TestWriteEnvFileCreate(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueUpdate,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err != nil {
+		t.Fatalf("WriteFile failed: %v", err)
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != expectCreate {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	}
+}
+
+func TestWriteEnvFileNoop(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+	ioutil.WriteFile(fullPath, []byte(base), 0644)
+
+	oldStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueNoop,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err != nil {
+		t.Fatalf("WriteFile failed: %v", err)
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != base {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	}
+
+	newStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	if oldStat.Sys().(*syscall.Stat_t).Ino != newStat.Sys().(*syscall.Stat_t).Ino {
+		t.Fatalf("File was replaced: %s", fullPath)
+	}
+}
+
+func TestWriteEnvFileUpdateDos(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+	ioutil.WriteFile(fullPath, []byte(baseDos), 0644)
+
+	oldStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueUpdate,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err != nil {
+		t.Fatalf("WriteFile failed: %v", err)
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != expectUpdate {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	}
+
+	newStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	if oldStat.Sys().(*syscall.Stat_t).Ino == newStat.Sys().(*syscall.Stat_t).Ino {
+		t.Fatalf("File was not replaced: %s", fullPath)
+	}
+}
+
+// A middle ground noop, values are unchanged but we did have a value.
+// Seems reasonable to rewrite the file in Unix format anyway.
+func TestWriteEnvFileDos2Unix(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+	ioutil.WriteFile(fullPath, []byte(baseDos), 0644)
+
+	oldStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueNoop,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err != nil {
+		t.Fatalf("WriteFile failed: %v", err)
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != base {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	}
+
+	newStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	if oldStat.Sys().(*syscall.Stat_t).Ino == newStat.Sys().(*syscall.Stat_t).Ino {
+		t.Fatalf("File was not replaced: %s", fullPath)
+	}
+}
+
+// If it really is a noop (structure is empty) don't even do dos2unix
+func TestWriteEnvFileEmpty(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+	ioutil.WriteFile(fullPath, []byte(baseDos), 0644)
+
+	oldStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueEmpty,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err != nil {
+		t.Fatalf("WriteFile failed: %v", err)
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != baseDos {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	}
+
+	newStat, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	if oldStat.Sys().(*syscall.Stat_t).Ino != newStat.Sys().(*syscall.Stat_t).Ino {
+		t.Fatalf("File was replaced: %s", fullPath)
+	}
+}
+
+// no point in creating empty files
+func TestWriteEnvFileEmptyNoCreate(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueEmpty,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err != nil {
+		t.Fatalf("WriteFile failed: %v", err)
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err == nil {
+		t.Fatalf("File has incorrect contents: %q", contents)
+	} else if !os.IsNotExist(err) {
+		t.Fatalf("Unexpected error while reading file: %v", err)
+	}
+}
+
+func TestWriteEnvFilePermFailure(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+	fullPath := path.Join(dir, name)
+	ioutil.WriteFile(fullPath, []byte(base), 0000)
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueUpdate,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if !os.IsPermission(err) {
+		t.Fatalf("Not a pemission denied error: %v", err)
+	}
+}
+
+func TestWriteEnvFileNameFailure(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	name := "foo.conf"
+
+	ef := EnvFile{
+		File: &File{config.File{
+			Path: name,
+		}},
+		Vars: valueInvalid,
+	}
+
+	err = WriteEnvFile(&ef, dir)
+	if err == nil || !strings.HasPrefix(err.Error(), "Invalid name") {
+		t.Fatalf("Not an invalid name error: %v", err)
+	}
+}
--- a/system/etc_hosts.go
+++ b/system/etc_hosts.go
@@ -0,0 +1,48 @@
+package system
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+const DefaultIpv4Address = "127.0.0.1"
+
+type EtcHosts struct {
+	Config config.EtcHosts
+}
+
+func (eh EtcHosts) generateEtcHosts() (out string, err error) {
+	if eh.Config != "localhost" {
+		return "", errors.New("Invalid option to manage_etc_hosts")
+	}
+
+	// use the operating system hostname
+	hostname, err := os.Hostname()
+	if err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("%s %s\n", DefaultIpv4Address, hostname), nil
+
+}
+
+func (eh EtcHosts) File() (*File, error) {
+	if eh.Config == "" {
+		return nil, nil
+	}
+
+	etcHosts, err := eh.generateEtcHosts()
+	if err != nil {
+		return nil, err
+	}
+
+	return &File{config.File{
+		Path:               path.Join("etc", "hosts"),
+		RawFilePermissions: "0644",
+		Content:            etcHosts,
+	}}, nil
+}
--- a/system/etc_hosts_test.go
+++ b/system/etc_hosts_test.go
@@ -0,0 +1,46 @@
+package system
+
+import (
+	"fmt"
+	"os"
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+func TestEtcdHostsFile(t *testing.T) {
+	hostname, err := os.Hostname()
+	if err != nil {
+		panic(err)
+	}
+
+	for _, tt := range []struct {
+		config config.EtcHosts
+		file   *File
+		err    error
+	}{
+		{
+			"invalid",
+			nil,
+			fmt.Errorf("Invalid option to manage_etc_hosts"),
+		},
+		{
+			"localhost",
+			&File{config.File{
+				Content:            fmt.Sprintf("127.0.0.1 %s\n", hostname),
+				Path:               "etc/hosts",
+				RawFilePermissions: "0644",
+			}},
+			nil,
+		},
+	} {
+		file, err := EtcHosts{tt.config}.File()
+		if !reflect.DeepEqual(tt.err, err) {
+			t.Errorf("bad error (%q): want %q, got %q", tt.config, tt.err, err)
+		}
+		if !reflect.DeepEqual(tt.file, file) {
+			t.Errorf("bad units (%q): want %#v, got %#v", tt.config, tt.file, file)
+		}
+	}
+}
--- a/system/etcd.go
+++ b/system/etcd.go
@@ -0,0 +1,25 @@
+package system
+
+import (
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+// Etcd is a top-level structure which embeds its underlying configuration,
+// config.Etcd, and provides the system-specific Unit().
+type Etcd struct {
+	config.Etcd
+}
+
+// Units creates a Unit file drop-in for etcd, using any configured options.
+func (ee Etcd) Units() ([]Unit, error) {
+	content := dropinContents(ee.Etcd)
+	if content == "" {
+		return nil, nil
+	}
+	return []Unit{{config.Unit{
+		Name:    "etcd.service",
+		Runtime: true,
+		DropIn:  true,
+		Content: content,
+	}}}, nil
+}
--- a/system/etcd_test.go
+++ b/system/etcd_test.go
@@ -0,0 +1,60 @@
+package system
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+func TestEtcdUnits(t *testing.T) {
+	for _, tt := range []struct {
+		config config.Etcd
+		units  []Unit
+	}{
+		{
+			config.Etcd{},
+			nil,
+		},
+		{
+			config.Etcd{
+				Discovery:    "http://disco.example.com/foobar",
+				PeerBindAddr: "127.0.0.1:7002",
+			},
+			[]Unit{{config.Unit{
+				Name:    "etcd.service",
+				Runtime: true,
+				DropIn:  true,
+				Content: `[Service]
+Environment="ETCD_DISCOVERY=http://disco.example.com/foobar"
+Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
+`,
+			}}},
+		},
+		{
+			config.Etcd{
+				Name:         "node001",
+				Discovery:    "http://disco.example.com/foobar",
+				PeerBindAddr: "127.0.0.1:7002",
+			},
+			[]Unit{{config.Unit{
+				Name:    "etcd.service",
+				Runtime: true,
+				DropIn:  true,
+				Content: `[Service]
+Environment="ETCD_DISCOVERY=http://disco.example.com/foobar"
+Environment="ETCD_NAME=node001"
+Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
+`,
+			}}},
+		},
+	} {
+		units, err := Etcd{tt.config}.Units()
+		if err != nil {
+			t.Errorf("bad error (%q): want %q, got %q", tt.config, nil, err)
+		}
+		if !reflect.DeepEqual(tt.units, units) {
+			t.Errorf("bad units (%q): want %#v, got %#v", tt.config, tt.units, units)
+		}
+	}
+}
--- a/system/file.go
+++ b/system/file.go
@@ -8,14 +8,14 @@ import (
 	"os/exec"
 	"path"
 	"strconv"
+
+	"github.com/coreos/coreos-cloudinit/config"
 )

+// File is a top-level structure which embeds its underlying configuration,
+// config.File, and provides the system-specific Permissions().
 type File struct {
-	Encoding           string
-	Content            string
-	Owner              string
-	Path               string
-	RawFilePermissions string `yaml:"permissions"`
+	config.File
 }

 func (f *File) Permissions() (os.FileMode, error) {
@@ -31,33 +31,55 @@ func (f *File) Permissions() (os.FileMode, error) {
 	return os.FileMode(perm), nil
 }

-func WriteFile(f *File) error {
+func WriteFile(f *File, root string) (string, error) {
 	if f.Encoding != "" {
-		return fmt.Errorf("Unable to write file with encoding %s", f.Encoding)
+		return "", fmt.Errorf("Unable to write file with encoding %s", f.Encoding)
 	}

-	if err := os.MkdirAll(path.Dir(f.Path), os.FileMode(0755)); err != nil {
-		return err
+	fullpath := path.Join(root, f.Path)
+	dir := path.Dir(fullpath)
+
+	if err := EnsureDirectoryExists(dir); err != nil {
+		return "", err
 	}

 	perm, err := f.Permissions()
 	if err != nil {
-		return err
+		return "", err
 	}

-	if err := ioutil.WriteFile(f.Path, []byte(f.Content), perm); err != nil {
-		return err
+	var tmp *os.File
+	// Create a temporary file in the same directory to ensure it's on the same filesystem
+	if tmp, err = ioutil.TempFile(dir, "cloudinit-temp"); err != nil {
+		return "", err
+	}
+
+	if err := ioutil.WriteFile(tmp.Name(), []byte(f.Content), perm); err != nil {
+		return "", err
+	}
+
+	if err := tmp.Close(); err != nil {
+		return "", err
+	}
+
+	// Ensure the permissions are as requested (since WriteFile can be affected by sticky bit)
+	if err := os.Chmod(tmp.Name(), perm); err != nil {
+		return "", err
 	}

 	if f.Owner != "" {
 		// We shell out since we don't have a way to look up unix groups natively
-		cmd := exec.Command("chown", f.Owner, f.Path)
+		cmd := exec.Command("chown", f.Owner, tmp.Name())
 		if err := cmd.Run(); err != nil {
-			return err
+			return "", err
 		}
 	}

-	return nil
+	if err := os.Rename(tmp.Name(), fullpath); err != nil {
+		return "", err
+	}
+
+	return fullpath, nil
 }

 func EnsureDirectoryExists(dir string) error {
--- a/system/file_test.go
+++ b/system/file_test.go
@@ -4,8 +4,9 @@ import (
 	"io/ioutil"
 	"os"
 	"path"
-	"syscall"
 	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
 )

 func TestWriteFileUnencodedContent(t *testing.T) {
@@ -13,18 +14,22 @@ func TestWriteFileUnencodedContent(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unable to create tempdir: %v", err)
 	}
-	defer syscall.Rmdir(dir)
+	defer os.RemoveAll(dir)

-	fullPath := path.Join(dir, "tmp", "foo")
+	fn := "foo"
+	fullPath := path.Join(dir, fn)

-	wf := File{
-		Path:        fullPath,
+	wf := File{config.File{
+		Path:               fn,
 		Content:            "bar",
 		RawFilePermissions: "0644",
-	}
+	}}

-	if err := WriteFile(&wf); err != nil {
+	path, err := WriteFile(&wf, dir)
+	if err != nil {
 		t.Fatalf("Processing of WriteFile failed: %v", err)
+	} else if path != fullPath {
+		t.Fatalf("WriteFile returned bad path: want %s, got %s", fullPath, path)
 	}

 	fi, err := os.Stat(fullPath)
@@ -51,15 +56,15 @@ func TestWriteFileInvalidPermission(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unable to create tempdir: %v", err)
 	}
-	defer syscall.Rmdir(dir)
+	defer os.RemoveAll(dir)

-	wf := File{
+	wf := File{config.File{
 		Path:               path.Join(dir, "tmp", "foo"),
 		Content:            "bar",
 		RawFilePermissions: "pants",
-	}
+	}}

-	if err := WriteFile(&wf); err == nil {
+	if _, err := WriteFile(&wf, dir); err == nil {
 		t.Fatalf("Expected error to be raised when writing file with invalid permission")
 	}
 }
@@ -69,17 +74,21 @@ func TestWriteFilePermissions(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unable to create tempdir: %v", err)
 	}
-	defer syscall.Rmdir(dir)
+	defer os.RemoveAll(dir)

-	fullPath := path.Join(dir, "tmp", "foo")
+	fn := "foo"
+	fullPath := path.Join(dir, fn)

-	wf := File{
-		Path:               fullPath,
+	wf := File{config.File{
+		Path:               fn,
 		RawFilePermissions: "0755",
-	}
+	}}

-	if err := WriteFile(&wf); err != nil {
+	path, err := WriteFile(&wf, dir)
+	if err != nil {
 		t.Fatalf("Processing of WriteFile failed: %v", err)
+	} else if path != fullPath {
+		t.Fatalf("WriteFile returned bad path: want %s, got %s", fullPath, path)
 	}

 	fi, err := os.Stat(fullPath)
@@ -97,15 +106,15 @@ func TestWriteFileEncodedContent(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unable to create tempdir: %v", err)
 	}
-	defer syscall.Rmdir(dir)
+	defer os.RemoveAll(dir)

-	wf := File{
+	wf := File{config.File{
 		Path:     path.Join(dir, "tmp", "foo"),
 		Content:  "",
 		Encoding: "base64",
-	}
+	}}

-	if err := WriteFile(&wf); err == nil {
+	if _, err := WriteFile(&wf, dir); err == nil {
 		t.Fatalf("Expected error to be raised when writing file with encoding")
 	}
 }
--- a/system/fleet.go
+++ b/system/fleet.go
@@ -0,0 +1,26 @@
+package system
+
+import (
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+// Fleet is a top-level structure which embeds its underlying configuration,
+// config.Fleet, and provides the system-specific Unit().
+type Fleet struct {
+	config.Fleet
+}
+
+// Units generates a Unit file drop-in for fleet, if any fleet options were
+// configured in cloud-config
+func (fe Fleet) Units() ([]Unit, error) {
+	content := dropinContents(fe.Fleet)
+	if content == "" {
+		return nil, nil
+	}
+	return []Unit{{config.Unit{
+		Name:    "fleet.service",
+		Runtime: true,
+		DropIn:  true,
+		Content: content,
+	}}}, nil
+}
--- a/system/fleet_test.go
+++ b/system/fleet_test.go
@@ -0,0 +1,41 @@
+package system
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+func TestFleetUnits(t *testing.T) {
+	for _, tt := range []struct {
+		config config.Fleet
+		units  []Unit
+	}{
+		{
+			config.Fleet{},
+			nil,
+		},
+		{
+			config.Fleet{
+				PublicIP: "12.34.56.78",
+			},
+			[]Unit{{config.Unit{
+				Name: "fleet.service",
+				Content: `[Service]
+Environment="FLEET_PUBLIC_IP=12.34.56.78"
+`,
+				Runtime: true,
+				DropIn:  true,
+			}}},
+		},
+	} {
+		units, err := Fleet{tt.config}.Units()
+		if err != nil {
+			t.Errorf("bad error (%q): want %q, got %q", tt.config, nil, err)
+		}
+		if !reflect.DeepEqual(units, tt.units) {
+			t.Errorf("bad units (%q): want %q, got %q", tt.config, tt.units, units)
+		}
+	}
+}
--- a/system/networkd.go
+++ b/system/networkd.go
@@ -0,0 +1,119 @@
+package system
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"os/exec"
+	"strings"
+	"time"
+
+	"github.com/coreos/coreos-cloudinit/config"
+	"github.com/coreos/coreos-cloudinit/network"
+	"github.com/coreos/coreos-cloudinit/third_party/github.com/dotcloud/docker/pkg/netlink"
+)
+
+const (
+	runtimeNetworkPath = "/run/systemd/network"
+)
+
+func RestartNetwork(interfaces []network.InterfaceGenerator) (err error) {
+	defer func() {
+		if e := restartNetworkd(); e != nil {
+			err = e
+			return
+		}
+		// TODO(crawford): Get rid of this once networkd fixes the race
+		// https://bugs.freedesktop.org/show_bug.cgi?id=76077
+		time.Sleep(5 * time.Second)
+		if e := restartNetworkd(); e != nil {
+			err = e
+		}
+	}()
+
+	if err = downNetworkInterfaces(interfaces); err != nil {
+		return
+	}
+
+	if err = maybeProbe8012q(interfaces); err != nil {
+		return
+	}
+	return maybeProbeBonding(interfaces)
+}
+
+func downNetworkInterfaces(interfaces []network.InterfaceGenerator) error {
+	sysInterfaceMap := make(map[string]*net.Interface)
+	if systemInterfaces, err := net.Interfaces(); err == nil {
+		for _, iface := range systemInterfaces {
+			iface := iface
+			sysInterfaceMap[iface.Name] = &iface
+		}
+	} else {
+		return err
+	}
+
+	for _, iface := range interfaces {
+		if systemInterface, ok := sysInterfaceMap[iface.Name()]; ok {
+			log.Printf("Taking down interface %q\n", systemInterface.Name)
+			if err := netlink.NetworkLinkDown(systemInterface); err != nil {
+				fmt.Printf("Error while downing interface %q (%s). Continuing...\n", systemInterface.Name, err)
+			}
+		}
+	}
+
+	return nil
+}
+
+func maybeProbe8012q(interfaces []network.InterfaceGenerator) error {
+	for _, iface := range interfaces {
+		if iface.Type() == "vlan" {
+			log.Printf("Probing LKM %q (%q)\n", "8021q", "8021q")
+			return exec.Command("modprobe", "8021q").Run()
+		}
+	}
+	return nil
+}
+
+func maybeProbeBonding(interfaces []network.InterfaceGenerator) error {
+	for _, iface := range interfaces {
+		if iface.Type() == "bond" {
+			args := append([]string{"bonding"}, strings.Split(iface.ModprobeParams(), " ")...)
+			log.Printf("Probing LKM %q (%q)\n", "bonding", args)
+			return exec.Command("modprobe", args...).Run()
+		}
+	}
+	return nil
+}
+
+func restartNetworkd() error {
+	log.Printf("Restarting networkd.service\n")
+	_, err := NewUnitManager("").RunUnitCommand("restart", "systemd-networkd.service")
+	return err
+}
+
+func WriteNetworkdConfigs(interfaces []network.InterfaceGenerator) error {
+	for _, iface := range interfaces {
+		filename := fmt.Sprintf("%s.netdev", iface.Filename())
+		if err := writeConfig(filename, iface.Netdev()); err != nil {
+			return err
+		}
+		filename = fmt.Sprintf("%s.link", iface.Filename())
+		if err := writeConfig(filename, iface.Link()); err != nil {
+			return err
+		}
+		filename = fmt.Sprintf("%s.network", iface.Filename())
+		if err := writeConfig(filename, iface.Network()); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func writeConfig(filename string, content string) error {
+	if content == "" {
+		return nil
+	}
+	log.Printf("Writing networkd unit %q\n", filename)
+	_, err := WriteFile(&File{config.File{Content: content, Path: filename}}, runtimeNetworkPath)
+	return err
+}
--- a/system/oem.go
+++ b/system/oem.go
@@ -0,0 +1,32 @@
+package system
+
+import (
+	"fmt"
+	"path"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+// OEM is a top-level structure which embeds its underlying configuration,
+// config.OEM, and provides the system-specific File().
+type OEM struct {
+	config.OEM
+}
+
+func (oem OEM) File() (*File, error) {
+	if oem.ID == "" {
+		return nil, nil
+	}
+
+	content := fmt.Sprintf("ID=%s\n", oem.ID)
+	content += fmt.Sprintf("VERSION_ID=%s\n", oem.VersionID)
+	content += fmt.Sprintf("NAME=%q\n", oem.Name)
+	content += fmt.Sprintf("HOME_URL=%q\n", oem.HomeURL)
+	content += fmt.Sprintf("BUG_REPORT_URL=%q\n", oem.BugReportURL)
+
+	return &File{config.File{
+		Path:               path.Join("etc", "oem-release"),
+		RawFilePermissions: "0644",
+		Content:            content,
+	}}, nil
+}
--- a/system/oem_test.go
+++ b/system/oem_test.go
@@ -0,0 +1,47 @@
+package system
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+func TestOEMFile(t *testing.T) {
+	for _, tt := range []struct {
+		config config.OEM
+		file   *File
+	}{
+		{
+			config.OEM{},
+			nil,
+		},
+		{
+			config.OEM{
+				ID:           "rackspace",
+				Name:         "Rackspace Cloud Servers",
+				VersionID:    "168.0.0",
+				HomeURL:      "https://www.rackspace.com/cloud/servers/",
+				BugReportURL: "https://github.com/coreos/coreos-overlay",
+			},
+			&File{config.File{
+				Path:               "etc/oem-release",
+				RawFilePermissions: "0644",
+				Content: `ID=rackspace
+VERSION_ID=168.0.0
+NAME="Rackspace Cloud Servers"
+HOME_URL="https://www.rackspace.com/cloud/servers/"
+BUG_REPORT_URL="https://github.com/coreos/coreos-overlay"
+`,
+			}},
+		},
+	} {
+		file, err := OEM{tt.config}.File()
+		if err != nil {
+			t.Errorf("bad error (%q): want %q, got %q", tt.config, nil, err)
+		}
+		if !reflect.DeepEqual(tt.file, file) {
+			t.Errorf("bad file (%q): want %#v, got %#v", tt.config, tt.file, file)
+		}
+	}
+}
--- a/system/systemd.go
+++ b/system/systemd.go
@@ -10,53 +10,25 @@ import (
 	"path/filepath"
 	"strings"

+	"github.com/coreos/coreos-cloudinit/config"
 	"github.com/coreos/coreos-cloudinit/third_party/github.com/coreos/go-systemd/dbus"
 )

+func NewUnitManager(root string) UnitManager {
+	return &systemd{root}
+}
+
+type systemd struct {
+	root string
+}
+
 // fakeMachineID is placed on non-usr CoreOS images and should
 // never be used as a true MachineID
 const fakeMachineID = "42000000000000000000000000000042"

-type Unit struct {
-	Name    string
-	Enable  bool
-	Runtime bool
-	Content string
-	Command string
-}
-
-func (u *Unit) Type() string {
-	ext := filepath.Ext(u.Name)
-	return strings.TrimLeft(ext, ".")
-}
-
-func (u *Unit) Group() (group string) {
-	t := u.Type()
-	if t == "network" || t == "netdev" || t == "link" {
-		group = "network"
-	} else {
-		group = "system"
-	}
-	return
-}
-
-type Script []byte
-
-// UnitDestination builds the appropriate absolte file path for
-// the given unit. The root argument indicates the effective base
-// directory of the system (similar to a chroot).
-func UnitDestination(u *Unit, root string) string {
-	dir := "etc"
-	if u.Runtime {
-		dir = "run"
-	}
-
-	return path.Join(root, dir, "systemd", u.Group(), u.Name)
-}
-
 // PlaceUnit writes a unit file at the provided destination, creating
 // parent directories as necessary.
-func PlaceUnit(u *Unit, dst string) error {
+func (s *systemd) PlaceUnit(u *Unit, dst string) error {
 	dir := filepath.Dir(dst)
 	if _, err := os.Stat(dir); os.IsNotExist(err) {
 		if err := os.MkdirAll(dir, os.FileMode(0755)); err != nil {
@@ -64,13 +36,13 @@ func PlaceUnit(u *Unit, dst string) error {
 		}
 	}

-	file := File{
-		Path:               dst,
+	file := File{config.File{
+		Path:               filepath.Base(dst),
 		Content:            u.Content,
 		RawFilePermissions: "0644",
-	}
+	}}

-	err := WriteFile(&file)
+	_, err := WriteFile(&file, dir)
 	if err != nil {
 		return err
 	}
@@ -78,18 +50,18 @@ func PlaceUnit(u *Unit, dst string) error {
 	return nil
 }

-func EnableUnitFile(file string, runtime bool) error {
+func (s *systemd) EnableUnitFile(unit string, runtime bool) error {
 	conn, err := dbus.New()
 	if err != nil {
 		return err
 	}

-	files := []string{file}
-	_, _, err = conn.EnableUnitFiles(files, runtime, true)
+	units := []string{unit}
+	_, _, err = conn.EnableUnitFiles(units, runtime, true)
 	return err
 }

-func RunUnitCommand(command, unit string) (string, error) {
+func (s *systemd) RunUnitCommand(command, unit string) (string, error) {
 	conn, err := dbus.New()
 	if err != nil {
 		return "", err
@@ -118,7 +90,7 @@ func RunUnitCommand(command, unit string) (string, error) {
 	return fn(unit, "replace")
 }

-func DaemonReload() error {
+func (s *systemd) DaemonReload() error {
 	conn, err := dbus.New()
 	if err != nil {
 		return err
@@ -127,6 +99,57 @@ func DaemonReload() error {
 	return conn.Reload()
 }

+// MaskUnit masks the given Unit by symlinking its unit file to
+// /dev/null, analogous to `systemctl mask`.
+// N.B.: Unlike `systemctl mask`, this function will *remove any existing unit
+// file at the location*, to ensure that the mask will succeed.
+func (s *systemd) MaskUnit(unit *Unit) error {
+	masked := unit.Destination(s.root)
+	if _, err := os.Stat(masked); os.IsNotExist(err) {
+		if err := os.MkdirAll(path.Dir(masked), os.FileMode(0755)); err != nil {
+			return err
+		}
+	} else if err := os.Remove(masked); err != nil {
+		return err
+	}
+	return os.Symlink("/dev/null", masked)
+}
+
+// UnmaskUnit is analogous to systemd's unit_file_unmask. If the file
+// associated with the given Unit is empty or appears to be a symlink to
+// /dev/null, it is removed.
+func (s *systemd) UnmaskUnit(unit *Unit) error {
+	masked := unit.Destination(s.root)
+	ne, err := nullOrEmpty(masked)
+	if os.IsNotExist(err) {
+		return nil
+	} else if err != nil {
+		return err
+	}
+	if !ne {
+		log.Printf("%s is not null or empty, refusing to unmask", masked)
+		return nil
+	}
+	return os.Remove(masked)
+}
+
+// nullOrEmpty checks whether a given path appears to be an empty regular file
+// or a symlink to /dev/null
+func nullOrEmpty(path string) (bool, error) {
+	fi, err := os.Stat(path)
+	if err != nil {
+		return false, err
+	}
+	m := fi.Mode()
+	if m.IsRegular() && fi.Size() <= 0 {
+		return true, nil
+	}
+	if m&os.ModeCharDevice > 0 {
+		return true, nil
+	}
+	return false, nil
+}
+
 func ExecuteScript(scriptPath string) (string, error) {
 	props := []dbus.Property{
 		dbus.PropDescription("Unit generated and executed by coreos-cloudinit on behalf of user"),
@@ -165,11 +188,3 @@ func MachineID(root string) string {

 	return id
 }
-
-func MaskUnit(unit string, root string) error {
-	masked := path.Join(root, "etc", "systemd", "system", unit)
-	if err := os.MkdirAll(path.Dir(masked), os.FileMode(0755)); err != nil {
-		return err
-	}
-	return os.Symlink("/dev/null", masked)
-}
--- a/system/systemd_test.go
+++ b/system/systemd_test.go
@@ -5,10 +5,12 @@ import (
 	"os"
 	"path"
 	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
 )

 func TestPlaceNetworkUnit(t *testing.T) {
-	u := Unit{
+	u := Unit{config.Unit{
 		Name:    "50-eth0.network",
 		Runtime: true,
 		Content: `[Match]
@@ -17,7 +19,7 @@ Name=eth47
 [Network]
 Address=10.209.171.177/19
 `,
-	}
+	}}

 	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
 	if err != nil {
@@ -25,13 +27,15 @@ Address=10.209.171.177/19
 	}
 	defer os.RemoveAll(dir)

-	dst := UnitDestination(&u, dir)
+	sd := &systemd{dir}
+
+	dst := u.Destination(dir)
 	expectDst := path.Join(dir, "run", "systemd", "network", "50-eth0.network")
 	if dst != expectDst {
-		t.Fatalf("UnitDestination returned %s, expected %s", dst, expectDst)
+		t.Fatalf("unit.Destination returned %s, expected %s", dst, expectDst)
 	}

-	if err := PlaceUnit(&u, dst); err != nil {
+	if err := sd.PlaceUnit(&u, dst); err != nil {
 		t.Fatalf("PlaceUnit failed: %v", err)
 	}

@@ -60,15 +64,39 @@ Address=10.209.171.177/19
 	}
 }

+func TestUnitDestination(t *testing.T) {
+	dir := "/some/dir"
+	name := "foobar.service"
+
+	u := Unit{config.Unit{
+		Name:   name,
+		DropIn: false,
+	}}
+
+	dst := u.Destination(dir)
+	expectDst := path.Join(dir, "etc", "systemd", "system", "foobar.service")
+	if dst != expectDst {
+		t.Errorf("unit.Destination returned %s, expected %s", dst, expectDst)
+	}
+
+	u.DropIn = true
+
+	dst = u.Destination(dir)
+	expectDst = path.Join(dir, "etc", "systemd", "system", "foobar.service.d", cloudConfigDropIn)
+	if dst != expectDst {
+		t.Errorf("unit.Destination returned %s, expected %s", dst, expectDst)
+	}
+}
+
 func TestPlaceMountUnit(t *testing.T) {
-	u := Unit{
+	u := Unit{config.Unit{
 		Name:    "media-state.mount",
 		Runtime: false,
 		Content: `[Mount]
 What=/dev/sdb1
 Where=/media/state
 `,
-	}
+	}}

 	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
 	if err != nil {
@@ -76,13 +104,15 @@ Where=/media/state
 	}
 	defer os.RemoveAll(dir)

-	dst := UnitDestination(&u, dir)
+	sd := &systemd{dir}
+
+	dst := u.Destination(dir)
 	expectDst := path.Join(dir, "etc", "systemd", "system", "media-state.mount")
 	if dst != expectDst {
-		t.Fatalf("UnitDestination returned %s, expected %s", dst, expectDst)
+		t.Fatalf("unit.Destination returned %s, expected %s", dst, expectDst)
 	}

-	if err := PlaceUnit(&u, dst); err != nil {
+	if err := sd.PlaceUnit(&u, dst); err != nil {
 		t.Fatalf("PlaceUnit failed: %v", err)
 	}

@@ -123,22 +153,137 @@ func TestMachineID(t *testing.T) {
 		t.Fatalf("File has incorrect contents")
 	}
 }
+
 func TestMaskUnit(t *testing.T) {
 	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
 	if err != nil {
 		t.Fatalf("Unable to create tempdir: %v", err)
 	}
 	defer os.RemoveAll(dir)
-	if err := MaskUnit("foo.service", dir); err != nil {
-		t.Fatalf("Unable to mask unit: %v", err)
-	}

-	fullPath := path.Join(dir, "etc", "systemd", "system", "foo.service")
-	target, err := os.Readlink(fullPath)
+	sd := &systemd{dir}
+
+	// Ensure mask works with units that do not currently exist
+	uf := &Unit{config.Unit{Name: "foo.service"}}
+	if err := sd.MaskUnit(uf); err != nil {
+		t.Fatalf("Unable to mask new unit: %v", err)
+	}
+	fooPath := path.Join(dir, "etc", "systemd", "system", "foo.service")
+	fooTgt, err := os.Readlink(fooPath)
 	if err != nil {
 		t.Fatalf("Unable to read link", err)
 	}
-	if target != "/dev/null" {
-		t.Fatalf("unit not masked, got unit target", target)
+	if fooTgt != "/dev/null" {
+		t.Fatalf("unit not masked, got unit target", fooTgt)
+	}
+
+	// Ensure mask works with unit files that already exist
+	ub := &Unit{config.Unit{Name: "bar.service"}}
+	barPath := path.Join(dir, "etc", "systemd", "system", "bar.service")
+	if _, err := os.Create(barPath); err != nil {
+		t.Fatalf("Error creating new unit file: %v", err)
+	}
+	if err := sd.MaskUnit(ub); err != nil {
+		t.Fatalf("Unable to mask existing unit: %v", err)
+	}
+	barTgt, err := os.Readlink(barPath)
+	if err != nil {
+		t.Fatalf("Unable to read link", err)
+	}
+	if barTgt != "/dev/null" {
+		t.Fatalf("unit not masked, got unit target", barTgt)
 	}
 }
+
+func TestUnmaskUnit(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	sd := &systemd{dir}
+
+	nilUnit := &Unit{config.Unit{Name: "null.service"}}
+	if err := sd.UnmaskUnit(nilUnit); err != nil {
+		t.Errorf("unexpected error from unmasking nonexistent unit: %v", err)
+	}
+
+	uf := &Unit{config.Unit{Name: "foo.service", Content: "[Service]\nExecStart=/bin/true"}}
+	dst := uf.Destination(dir)
+	if err := os.MkdirAll(path.Dir(dst), os.FileMode(0755)); err != nil {
+		t.Fatalf("Unable to create unit directory: %v", err)
+	}
+	if _, err := os.Create(dst); err != nil {
+		t.Fatalf("Unable to write unit file: %v", err)
+	}
+
+	if err := ioutil.WriteFile(dst, []byte(uf.Content), 700); err != nil {
+		t.Fatalf("Unable to write unit file: %v", err)
+	}
+	if err := sd.UnmaskUnit(uf); err != nil {
+		t.Errorf("unmask of non-empty unit returned unexpected error: %v", err)
+	}
+	got, _ := ioutil.ReadFile(dst)
+	if string(got) != uf.Content {
+		t.Errorf("unmask of non-empty unit mutated unit contents unexpectedly")
+	}
+
+	ub := &Unit{config.Unit{Name: "bar.service"}}
+	dst = ub.Destination(dir)
+	if err := os.Symlink("/dev/null", dst); err != nil {
+		t.Fatalf("Unable to create masked unit: %v", err)
+	}
+	if err := sd.UnmaskUnit(ub); err != nil {
+		t.Errorf("unmask of unit returned unexpected error: %v", err)
+	}
+	if _, err := os.Stat(dst); !os.IsNotExist(err) {
+		t.Errorf("expected %s to not exist after unmask, but got err: %s", err)
+	}
+}
+
+func TestNullOrEmpty(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	non := path.Join(dir, "does_not_exist")
+	ne, err := nullOrEmpty(non)
+	if !os.IsNotExist(err) {
+		t.Errorf("nullOrEmpty on nonexistent file returned bad error: %v", err)
+	}
+	if ne {
+		t.Errorf("nullOrEmpty returned true unxpectedly")
+	}
+
+	regEmpty := path.Join(dir, "regular_empty_file")
+	_, err = os.Create(regEmpty)
+	if err != nil {
+		t.Fatalf("Unable to create tempfile: %v", err)
+	}
+	gotNe, gotErr := nullOrEmpty(regEmpty)
+	if !gotNe || gotErr != nil {
+		t.Errorf("nullOrEmpty of regular empty file returned %t, %v - want true, nil", gotNe, gotErr)
+	}
+
+	reg := path.Join(dir, "regular_file")
+	if err := ioutil.WriteFile(reg, []byte("asdf"), 700); err != nil {
+		t.Fatalf("Unable to create tempfile: %v", err)
+	}
+	gotNe, gotErr = nullOrEmpty(reg)
+	if gotNe || gotErr != nil {
+		t.Errorf("nullOrEmpty of regular file returned %t, %v - want false, nil", gotNe, gotErr)
+	}
+
+	null := path.Join(dir, "null")
+	if err := os.Symlink(os.DevNull, null); err != nil {
+		t.Fatalf("Unable to create /dev/null link: %s", err)
+	}
+	gotNe, gotErr = nullOrEmpty(null)
+	if !gotNe || gotErr != nil {
+		t.Errorf("nullOrEmpty of null symlink returned %t, %v - want true, nil", gotNe, gotErr)
+	}
+
+}
--- a/system/unit.go
+++ b/system/unit.go
@@ -0,0 +1,44 @@
+package system
+
+import (
+	"fmt"
+	"path"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+// Name for drop-in service configuration files created by cloudconfig
+const cloudConfigDropIn = "20-cloudinit.conf"
+
+type UnitManager interface {
+	PlaceUnit(unit *Unit, dst string) error
+	EnableUnitFile(unit string, runtime bool) error
+	RunUnitCommand(command, unit string) (string, error)
+	DaemonReload() error
+	MaskUnit(unit *Unit) error
+	UnmaskUnit(unit *Unit) error
+}
+
+// Unit is a top-level structure which embeds its underlying configuration,
+// config.Unit, and provides the system-specific Destination().
+type Unit struct {
+	config.Unit
+}
+
+type Script []byte
+
+// Destination builds the appropriate absolute file path for
+// the Unit. The root argument indicates the effective base
+// directory of the system (similar to a chroot).
+func (u *Unit) Destination(root string) string {
+	dir := "etc"
+	if u.Runtime {
+		dir = "run"
+	}
+
+	if u.DropIn {
+		return path.Join(root, dir, "systemd", u.Group(), fmt.Sprintf("%s.d", u.Name), cloudConfigDropIn)
+	} else {
+		return path.Join(root, dir, "systemd", u.Group(), u.Name)
+	}
+}
--- a/system/update.go
+++ b/system/update.go
@@ -0,0 +1,137 @@
+package system
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"path"
+	"reflect"
+	"sort"
+	"strings"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+const (
+	locksmithUnit    = "locksmithd.service"
+	updateEngineUnit = "update-engine.service"
+)
+
+// Update is a top-level structure which contains its underlying configuration,
+// config.Update, a function for reading the configuration (the default
+// implementation reading from the filesystem), and provides the system-specific
+// File() and Unit().
+type Update struct {
+	Config     config.Update
+	ReadConfig func() (io.Reader, error)
+}
+
+func DefaultReadConfig() (io.Reader, error) {
+	etcUpdate := path.Join("/etc", "coreos", "update.conf")
+	usrUpdate := path.Join("/usr", "share", "coreos", "update.conf")
+
+	f, err := os.Open(etcUpdate)
+	if os.IsNotExist(err) {
+		f, err = os.Open(usrUpdate)
+	}
+	return f, err
+}
+
+// File generates an `/etc/coreos/update.conf` file (if any update
+// configuration options are set in cloud-config) by either rewriting the
+// existing file on disk, or starting from `/usr/share/coreos/update.conf`
+func (uc Update) File() (*File, error) {
+	if config.IsZero(uc.Config) {
+		return nil, nil
+	}
+	if err := config.AssertValid(uc.Config); err != nil {
+		return nil, err
+	}
+
+	// Generate the list of possible substitutions to be performed based on the options that are configured
+	subs := map[string]string{}
+	uct := reflect.TypeOf(uc.Config)
+	ucv := reflect.ValueOf(uc.Config)
+	for i := 0; i < uct.NumField(); i++ {
+		val := ucv.Field(i).String()
+		if val == "" {
+			continue
+		}
+		env := uct.Field(i).Tag.Get("env")
+		subs[env] = fmt.Sprintf("%s=%s", env, val)
+	}
+
+	conf, err := uc.ReadConfig()
+	if err != nil {
+		return nil, err
+	}
+	scanner := bufio.NewScanner(conf)
+
+	var out string
+	for scanner.Scan() {
+		line := scanner.Text()
+		for env, value := range subs {
+			if strings.HasPrefix(line, env) {
+				line = value
+				delete(subs, env)
+				break
+			}
+		}
+		out += line
+		out += "\n"
+		if err := scanner.Err(); err != nil {
+			return nil, err
+		}
+	}
+
+	for _, key := range sortedKeys(subs) {
+		out += subs[key]
+		out += "\n"
+	}
+
+	return &File{config.File{
+		Path:               path.Join("etc", "coreos", "update.conf"),
+		RawFilePermissions: "0644",
+		Content:            out,
+	}}, nil
+}
+
+// Units generates units for the cloud-init initializer to act on:
+// - a locksmith Unit, if "reboot-strategy" was set in cloud-config
+// - an update_engine Unit, if "group" or "server" was set in cloud-config
+func (uc Update) Units() ([]Unit, error) {
+	var units []Unit
+	if uc.Config.RebootStrategy != "" {
+		ls := &Unit{config.Unit{
+			Name:    locksmithUnit,
+			Command: "restart",
+			Mask:    false,
+			Runtime: true,
+		}}
+
+		if uc.Config.RebootStrategy == "off" {
+			ls.Command = "stop"
+			ls.Mask = true
+		}
+		units = append(units, *ls)
+	}
+
+	if uc.Config.Group != "" || uc.Config.Server != "" {
+		ue := Unit{config.Unit{
+			Name:    updateEngineUnit,
+			Command: "restart",
+		}}
+		units = append(units, ue)
+	}
+
+	return units, nil
+}
+
+func sortedKeys(m map[string]string) (keys []string) {
+	for key := range m {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	return
+}
--- a/system/update_test.go
+++ b/system/update_test.go
@@ -0,0 +1,151 @@
+package system
+
+import (
+	"errors"
+	"io"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+func testReadConfig(config string) func() (io.Reader, error) {
+	return func() (io.Reader, error) {
+		return strings.NewReader(config), nil
+	}
+}
+
+func TestUpdateUnits(t *testing.T) {
+	for _, tt := range []struct {
+		config config.Update
+		units  []Unit
+		err    error
+	}{
+		{
+			config: config.Update{},
+		},
+		{
+			config: config.Update{Group: "master", Server: "http://foo.com"},
+			units: []Unit{{config.Unit{
+				Name:    "update-engine.service",
+				Command: "restart",
+			}}},
+		},
+		{
+			config: config.Update{RebootStrategy: "best-effort"},
+			units: []Unit{{config.Unit{
+				Name:    "locksmithd.service",
+				Command: "restart",
+				Runtime: true,
+			}}},
+		},
+		{
+			config: config.Update{RebootStrategy: "etcd-lock"},
+			units: []Unit{{config.Unit{
+				Name:    "locksmithd.service",
+				Command: "restart",
+				Runtime: true,
+			}}},
+		},
+		{
+			config: config.Update{RebootStrategy: "reboot"},
+			units: []Unit{{config.Unit{
+				Name:    "locksmithd.service",
+				Command: "restart",
+				Runtime: true,
+			}}},
+		},
+		{
+			config: config.Update{RebootStrategy: "off"},
+			units: []Unit{{config.Unit{
+				Name:    "locksmithd.service",
+				Command: "stop",
+				Runtime: true,
+				Mask:    true,
+			}}},
+		},
+	} {
+		units, err := Update{tt.config, testReadConfig("")}.Units()
+		if !reflect.DeepEqual(tt.err, err) {
+			t.Errorf("bad error (%q): want %q, got %q", tt.config, tt.err, err)
+		}
+		if !reflect.DeepEqual(tt.units, units) {
+			t.Errorf("bad units (%q): want %#v, got %#v", tt.config, tt.units, units)
+		}
+	}
+}
+
+func TestUpdateFile(t *testing.T) {
+	for _, tt := range []struct {
+		config config.Update
+		orig   string
+		file   *File
+		err    error
+	}{
+		{
+			config: config.Update{},
+		},
+		{
+			config: config.Update{RebootStrategy: "wizzlewazzle"},
+			err:    errors.New("invalid value \"wizzlewazzle\" for option \"RebootStrategy\" (valid options: \"best-effort,etcd-lock,reboot,off\")"),
+		},
+		{
+			config: config.Update{Group: "master", Server: "http://foo.com"},
+			file: &File{config.File{
+				Content:            "GROUP=master\nSERVER=http://foo.com\n",
+				Path:               "etc/coreos/update.conf",
+				RawFilePermissions: "0644",
+			}},
+		},
+		{
+			config: config.Update{RebootStrategy: "best-effort"},
+			file: &File{config.File{
+				Content:            "REBOOT_STRATEGY=best-effort\n",
+				Path:               "etc/coreos/update.conf",
+				RawFilePermissions: "0644",
+			}},
+		},
+		{
+			config: config.Update{RebootStrategy: "etcd-lock"},
+			file: &File{config.File{
+				Content:            "REBOOT_STRATEGY=etcd-lock\n",
+				Path:               "etc/coreos/update.conf",
+				RawFilePermissions: "0644",
+			}},
+		},
+		{
+			config: config.Update{RebootStrategy: "reboot"},
+			file: &File{config.File{
+				Content:            "REBOOT_STRATEGY=reboot\n",
+				Path:               "etc/coreos/update.conf",
+				RawFilePermissions: "0644",
+			}},
+		},
+		{
+			config: config.Update{RebootStrategy: "off"},
+			file: &File{config.File{
+				Content:            "REBOOT_STRATEGY=off\n",
+				Path:               "etc/coreos/update.conf",
+				RawFilePermissions: "0644",
+			}},
+		},
+		{
+			config: config.Update{RebootStrategy: "etcd-lock"},
+			orig:   "SERVER=https://example.com\nGROUP=thegroupc\nREBOOT_STRATEGY=awesome",
+			file: &File{config.File{
+				Content:            "SERVER=https://example.com\nGROUP=thegroupc\nREBOOT_STRATEGY=etcd-lock\n",
+				Path:               "etc/coreos/update.conf",
+				RawFilePermissions: "0644",
+			}},
+		},
+	} {
+		file, err := Update{tt.config, testReadConfig(tt.orig)}.File()
+		if !reflect.DeepEqual(tt.err, err) {
+			t.Errorf("bad error (%q): want %q, got %q", tt.config, tt.err, err)
+		}
+		if !reflect.DeepEqual(tt.file, file) {
+			t.Errorf("bad units (%q): want %#v, got %#v", tt.config, tt.file, file)
+		}
+	}
+}
--- a/system/user.go
+++ b/system/user.go
@@ -6,30 +6,16 @@ import (
 	"os/exec"
 	"os/user"
 	"strings"
+
+	"github.com/coreos/coreos-cloudinit/config"
 )

-type User struct {
-	Name                string   `yaml:"name"`
-	PasswordHash        string   `yaml:"passwd"`
-	SSHAuthorizedKeys   []string `yaml:"ssh-authorized-keys"`
-	SSHImportGithubUser string   `yaml:"coreos-ssh-import-github"`
-	SSHImportURL        string   `yaml:"coreos-ssh-import-url"`
-	GECOS               string   `yaml:"gecos"`
-	Homedir             string   `yaml:"homedir"`
-	NoCreateHome        bool     `yaml:"no-create-home"`
-	PrimaryGroup        string   `yaml:"primary-group"`
-	Groups              []string `yaml:"groups"`
-	NoUserGroup         bool     `yaml:"no-user-group"`
-	System              bool     `yaml:"system"`
-	NoLogInit           bool     `yaml:"no-log-init"`
-}
-
-func UserExists(u *User) bool {
+func UserExists(u *config.User) bool {
 	_, err := user.Lookup(u.Name)
 	return err == nil
 }

-func CreateUser(u *User) error {
+func CreateUser(u *config.User) error {
 	args := []string{}

 	if u.PasswordHash != "" {
@@ -53,7 +39,7 @@ func CreateUser(u *User) error {
 	}

 	if u.PrimaryGroup != "" {
-		args = append(args, "--primary-group", u.PrimaryGroup)
+		args = append(args, "--gid", u.PrimaryGroup)
 	}

 	if len(u.Groups) > 0 {
--- a/58
+++ b/58
@@ -1,10 +1,56 @@
 #!/bin/bash -e
+#
+# Run all coreos-cloudinit tests
+#   ./test
+#   ./test -v
+#
+# Run tests for one package
+#   PKG=initialize ./test
+#

-echo "Building bin/coreos-cloudinit"
-. build
+# Invoke ./cover for HTML output
+COVER=${COVER:-"-cover"}
+
+source ./build
+
+declare -a TESTPKGS=(
+	config
+	datasource
+	datasource/configdrive
+	datasource/file
+	datasource/metadata
+	datasource/metadata/cloudsigma
+	datasource/metadata/digitalocean
+	datasource/metadata/ec2
+	datasource/proc_cmdline
+	datasource/url
+	initialize
+	network
+	pkg
+	system
+)
+
+if [ -z "$PKG" ]; then
+	GOFMTPATH="${TESTPKGS[*]} coreos-cloudinit.go"
+	# prepend repo path to each package
+	TESTPKGS="${TESTPKGS[*]/#/${REPO_PATH}/} ./"
+else
+	GOFMTPATH="$TESTPKGS"
+	# strip out slashes and dots from PKG=./foo/
+	TESTPKGS=${PKG//\//}
+	TESTPKGS=${TESTPKGS//./}
+	TESTPKGS=${TESTPKGS/#/${REPO_PATH}/}
+fi

 echo "Running tests..."
-for pkg in "./initialize ./system ./datasource"; do
-	go test -i $pkg
-	go test -v $pkg
-done
+go test -i ${TESTPKGS}
+go test ${COVER} $@ ${TESTPKGS}
+
+echo "Checking gofmt..."
+fmtRes=$(gofmt -l $GOFMTPATH)
+if [ -n "$fmtRes" ]; then
+	echo "$fmtRes"
+	exit 1
+fi
+
+echo "Success"
--- a/third_party/github.com/cloudsigma/cepgo/LICENSE
+++ b/third_party/github.com/cloudsigma/cepgo/LICENSE
@@ -0,0 +1,202 @@
+Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
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+      Work and such Derivative Works in Source or Object form.
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+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
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+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
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+
+   4. Redistribution. You may reproduce and distribute copies of the
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+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "{}"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright {yyyy} {name of copyright owner}
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+
--- a/third_party/github.com/cloudsigma/cepgo/README.md
+++ b/third_party/github.com/cloudsigma/cepgo/README.md
@@ -0,0 +1,43 @@
+cepgo
+=====
+
+Cepko implements easy-to-use communication with CloudSigma's VMs through a
+virtual serial port without bothering with formatting the messages properly nor
+parsing the output with the specific and sometimes confusing shell tools for
+that purpose.
+
+Having the server definition accessible by the VM can be useful in various
+ways. For example it is possible to easily determine from within the VM, which
+network interfaces are connected to public and which to private network.
+Another use is to pass some data to initial VM setup scripts, like setting the
+hostname to the VM name or passing ssh public keys through server meta.
+
+Example usage:
+
+    package main
+
+    import (
+            "fmt"
+
+            "github.com/cloudsigma/cepgo"
+    )
+
+    func main() {
+            c := cepgo.NewCepgo()
+            result, err := c.Meta()
+            if err != nil {
+                    panic(err)
+            }
+            fmt.Printf("%#v", result)
+    }
+
+Output:
+
+    map[string]interface {}{
+        "optimize_for":"custom",
+        "ssh_public_key":"ssh-rsa AAA...",
+        "description":"[...]",
+    }
+
+For more information take a look at the Server Context section of CloudSigma
+API Docs: http://cloudsigma-docs.readthedocs.org/en/latest/server_context.html
--- a/third_party/github.com/cloudsigma/cepgo/cepgo.go
+++ b/third_party/github.com/cloudsigma/cepgo/cepgo.go
@@ -0,0 +1,186 @@
+// Cepko implements easy-to-use communication with CloudSigma's VMs through a
+// virtual serial port without bothering with formatting the messages properly
+// nor parsing the output with the specific and sometimes confusing shell tools
+// for that purpose.
+//
+// Having the server definition accessible by the VM can be useful in various
+// ways. For example it is possible to easily determine from within the VM,
+// which network interfaces are connected to public and which to private
+// network. Another use is to pass some data to initial VM setup scripts, like
+// setting the hostname to the VM name or passing ssh public keys through
+// server meta.
+//
+// Example usage:
+//
+//   package main
+//
+//   import (
+//           "fmt"
+//
+//           "github.com/cloudsigma/cepgo"
+//   )
+//
+//   func main() {
+//           c := cepgo.NewCepgo()
+//           result, err := c.Meta()
+//           if err != nil {
+//                   panic(err)
+//           }
+//           fmt.Printf("%#v", result)
+//   }
+//
+// Output:
+//
+//   map[string]string{
+//   	"optimize_for":"custom",
+//   	"ssh_public_key":"ssh-rsa AAA...",
+//   	"description":"[...]",
+//   }
+//
+// For more information take a look at the Server Context section API Docs:
+// http://cloudsigma-docs.readthedocs.org/en/latest/server_context.html
+package cepgo
+
+import (
+	"bufio"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"runtime"
+
+	"github.com/coreos/coreos-cloudinit/third_party/github.com/tarm/goserial"
+)
+
+const (
+	requestPattern = "<\n%s\n>"
+	EOT            = '\x04' // End Of Transmission
+)
+
+var (
+	SerialPort string = "/dev/ttyS1"
+	Baud       int    = 115200
+)
+
+// Sets the serial port. If the operating system is windows CloudSigma's server
+// context is at COM2 port, otherwise (linux, freebsd, darwin) the port is
+// being left to the default /dev/ttyS1.
+func init() {
+	if runtime.GOOS == "windows" {
+		SerialPort = "COM2"
+	}
+}
+
+// The default fetcher makes the connection to the serial port,
+// writes given query and reads until the EOT symbol.
+func fetchViaSerialPort(key string) ([]byte, error) {
+	config := &serial.Config{Name: SerialPort, Baud: Baud}
+	connection, err := serial.OpenPort(config)
+	if err != nil {
+		return nil, err
+	}
+
+	query := fmt.Sprintf(requestPattern, key)
+	if _, err := connection.Write([]byte(query)); err != nil {
+		return nil, err
+	}
+
+	reader := bufio.NewReader(connection)
+	answer, err := reader.ReadBytes(EOT)
+	if err != nil {
+		return nil, err
+	}
+
+	return answer[0 : len(answer)-1], nil
+}
+
+// Queries to the serial port can be executed only from instance of this type.
+// The result from each of them can be either interface{}, map[string]string or
+// a single in case of single value is returned. There is also a public metod
+// who directly calls the fetcher and returns raw []byte from the serial port.
+type Cepgo struct {
+	fetcher func(string) ([]byte, error)
+}
+
+// Creates a Cepgo instance with the default serial port fetcher.
+func NewCepgo() *Cepgo {
+	cepgo := new(Cepgo)
+	cepgo.fetcher = fetchViaSerialPort
+	return cepgo
+}
+
+// Creates a Cepgo instance with custom fetcher.
+func NewCepgoFetcher(fetcher func(string) ([]byte, error)) *Cepgo {
+	cepgo := new(Cepgo)
+	cepgo.fetcher = fetcher
+	return cepgo
+}
+
+// Fetches raw []byte from the serial port using directly the fetcher member.
+func (c *Cepgo) FetchRaw(key string) ([]byte, error) {
+	return c.fetcher(key)
+}
+
+// Fetches a single key and tries to unmarshal the result to json and returns
+// it. If the unmarshalling fails it's safe to assume the result it's just a
+// string and returns it.
+func (c *Cepgo) Key(key string) (interface{}, error) {
+	var result interface{}
+
+	fetched, err := c.FetchRaw(key)
+	if err != nil {
+		return nil, err
+	}
+
+	err = json.Unmarshal(fetched, &result)
+	if err != nil {
+		return string(fetched), nil
+	}
+	return result, nil
+}
+
+// Fetches all the server context. Equivalent of c.Key("")
+func (c *Cepgo) All() (interface{}, error) {
+	return c.Key("")
+}
+
+// Fetches only the object meta field and makes sure to return a proper
+// map[string]string
+func (c *Cepgo) Meta() (map[string]string, error) {
+	rawMeta, err := c.Key("/meta/")
+	if err != nil {
+		return nil, err
+	}
+
+	return typeAssertToMapOfStrings(rawMeta)
+}
+
+// Fetches only the global context and makes sure to return a proper
+// map[string]string
+func (c *Cepgo) GlobalContext() (map[string]string, error) {
+	rawContext, err := c.Key("/global_context/")
+	if err != nil {
+		return nil, err
+	}
+
+	return typeAssertToMapOfStrings(rawContext)
+}
+
+// Just a little helper function that uses type assertions in order to convert
+// a interface{} to map[string]string if this is possible.
+func typeAssertToMapOfStrings(raw interface{}) (map[string]string, error) {
+	result := make(map[string]string)
+
+	dictionary, ok := raw.(map[string]interface{})
+	if !ok {
+		return nil, errors.New("Received bytes are formatted badly")
+	}
+
+	for key, rawValue := range dictionary {
+		if value, ok := rawValue.(string); ok {
+			result[key] = value
+		} else {
+			return nil, errors.New("Server context metadata is formatted badly")
+		}
+	}
+	return result, nil
+}
--- a/third_party/github.com/cloudsigma/cepgo/cepgo_test.go
+++ b/third_party/github.com/cloudsigma/cepgo/cepgo_test.go
@@ -0,0 +1,122 @@
+package cepgo
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func fetchMock(key string) ([]byte, error) {
+	context := []byte(`{
+		"context": true,
+		"cpu": 4000,
+		"cpu_model": null,
+		"cpus_instead_of_cores": false,
+		"enable_numa": false,
+		"global_context": {
+			"some_global_key": "some_global_val"
+		},
+		"grantees": [],
+		"hv_relaxed": false,
+		"hv_tsc": false,
+		"jobs": [],
+		"mem": 4294967296,
+		"meta": {
+			"base64_fields": "cloudinit-user-data",
+			"cloudinit-user-data": "I2Nsb3VkLWNvbmZpZwoKaG9zdG5hbWU6IGNvcmVvczE=",
+			"ssh_public_key": "ssh-rsa AAAAB2NzaC1yc2E.../hQ5D5 john@doe"
+		},
+		"name": "coreos",
+		"nics": [
+			{
+				"runtime": {
+					"interface_type": "public",
+					"ip_v4": {
+						"uuid": "31.171.251.74"
+					},
+					"ip_v6": null
+				},
+				"vlan": null
+			}
+		],
+		"smp": 2,
+		"status": "running",
+		"uuid": "20a0059b-041e-4d0c-bcc6-9b2852de48b3"
+	}`)
+
+	if key == "" {
+		return context, nil
+	}
+
+	var marshalledContext map[string]interface{}
+
+	err := json.Unmarshal(context, &marshalledContext)
+	if err != nil {
+		return nil, err
+	}
+
+	if key[0] == '/' {
+		key = key[1:]
+	}
+	if key[len(key)-1] == '/' {
+		key = key[:len(key)-1]
+	}
+
+	return json.Marshal(marshalledContext[key])
+}
+
+func TestAll(t *testing.T) {
+	cepgo := NewCepgoFetcher(fetchMock)
+
+	result, err := cepgo.All()
+	if err != nil {
+		t.Error(err)
+	}
+
+	for _, key := range []string{"meta", "name", "uuid", "global_context"} {
+		if _, ok := result.(map[string]interface{})[key]; !ok {
+			t.Errorf("%s not in all keys", key)
+		}
+	}
+}
+
+func TestKey(t *testing.T) {
+	cepgo := NewCepgoFetcher(fetchMock)
+
+	result, err := cepgo.Key("uuid")
+	if err != nil {
+		t.Error(err)
+	}
+
+	if _, ok := result.(string); !ok {
+		t.Errorf("%#v\n", result)
+
+		t.Error("Fetching the uuid did not return a string")
+	}
+}
+
+func TestMeta(t *testing.T) {
+	cepgo := NewCepgoFetcher(fetchMock)
+
+	meta, err := cepgo.Meta()
+	if err != nil {
+		t.Errorf("%#v\n", meta)
+		t.Error(err)
+	}
+
+	if _, ok := meta["ssh_public_key"]; !ok {
+		t.Error("ssh_public_key is not in the meta")
+	}
+}
+
+func TestGlobalContext(t *testing.T) {
+	cepgo := NewCepgoFetcher(fetchMock)
+
+	result, err := cepgo.GlobalContext()
+	if err != nil {
+		t.Error(err)
+	}
+
+	if _, ok := result["some_global_key"]; !ok {
+		t.Error("some_global_key is not in the global context")
+	}
+}
--- a/third_party/github.com/dotcloud/docker/pkg/netlink/MAINTAINERS
+++ b/third_party/github.com/dotcloud/docker/pkg/netlink/MAINTAINERS
@@ -0,0 +1,2 @@
+Michael Crosby <michael@crosbymichael.com> (@crosbymichael)
+Guillaume J. Charmes <guillaume@docker.com> (@creack)
--- a/Show More
+++ b/Show More