datasource: replace metadata map with struct

The loosely-typed metadata map is a load of crap. Make it a struct and
let the compiler help us out.

datasource/configdrive/configdrive.go

@@ -15,10 +15,13 @@
 package configdrive
 
 import (
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"path"
+
+	"github.com/coreos/coreos-cloudinit/datasource"
 )
 
 const (
@@ -47,8 +50,28 @@ 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) FetchMetadata() (metadata datasource.Metadata, err error) {
+	var data []byte
+	var m struct {
+		SSHAuthorizedKeyMap map[string]string `json:"public_keys"`
+		Hostname            string            `json:"hostname"`
+		NetworkConfig       struct {
+			ContentPath string `json:"content_path"`
+		} `json:"network_config"`
+	}
+
+	if data, err = cd.tryReadFile(path.Join(cd.openstackVersionRoot(), "meta_data.json")); err != nil {
+		return
+	}
+	if err = json.Unmarshal([]byte(data), &m); err != nil {
+		return
+	}
+
+	metadata.SSHPublicKeys = m.SSHAuthorizedKeyMap
+	metadata.Hostname = m.Hostname
+	metadata.NetworkConfigPath = m.NetworkConfig.ContentPath
+
+	return
 }
 
 func (cd *configDrive) FetchUserdata() ([]byte, error) {

datasource/configdrive/configdrive_test.go

@@ -15,8 +15,10 @@
 package configdrive
 
 import (
+	"reflect"
 	"testing"
 
+	"github.com/coreos/coreos-cloudinit/datasource"
 	"github.com/coreos/coreos-cloudinit/datasource/test"
 )
 
@@ -25,22 +27,28 @@ func TestFetchMetadata(t *testing.T) {
 		root  string
 		files test.MockFilesystem
 
-		metadata string
+		metadata datasource.Metadata
 	}{
 		{
-			"/",
-			test.MockFilesystem{},
-			"",
+			root:  "/",
+			files: test.MockFilesystem{"/openstack/latest/meta_data.json": `{"ignore": "me"}`},
 		},
 		{
-			"/",
-			test.MockFilesystem{"/openstack/latest/meta_data.json": "metadata"},
-			"metadata",
+			root:     "/",
+			files:    test.MockFilesystem{"/openstack/latest/meta_data.json": `{"hostname": "host"}`},
+			metadata: datasource.Metadata{Hostname: "host"},
 		},
 		{
-			"/media/configdrive",
-			test.MockFilesystem{"/media/configdrive/openstack/latest/meta_data.json": "metadata"},
-			"metadata",
+			root:  "/media/configdrive",
+			files: test.MockFilesystem{"/media/configdrive/openstack/latest/meta_data.json": `{"hostname": "host", "network_config": {"content_path": "path"}, "public_keys":{"1": "key1", "2": "key2"}}`},
+			metadata: datasource.Metadata{
+				Hostname:          "host",
+				NetworkConfigPath: "path",
+				SSHPublicKeys: map[string]string{
+					"1": "key1",
+					"2": "key2",
+				},
+			},
 		},
 	} {
 		cd := configDrive{tt.root, tt.files.ReadFile}
@@ -48,8 +56,8 @@ func TestFetchMetadata(t *testing.T) {
 		if err != nil {
 			t.Fatalf("bad error for %q: want %v, got %q", tt, nil, err)
 		}
-		if string(metadata) != tt.metadata {
-			t.Fatalf("bad path for %q: want %q, got %q", tt, tt.metadata, metadata)
+		if !reflect.DeepEqual(tt.metadata, metadata) {
+			t.Fatalf("bad metadata for %q: want %#v, got %#v", tt, tt.metadata, metadata)
 		}
 	}
 }
@@ -83,7 +91,7 @@ func TestFetchUserdata(t *testing.T) {
 			t.Fatalf("bad error for %q: want %v, got %q", tt, nil, err)
 		}
 		if string(userdata) != tt.userdata {
-			t.Fatalf("bad path for %q: want %q, got %q", tt, tt.userdata, userdata)
+			t.Fatalf("bad userdata for %q: want %q, got %q", tt, tt.userdata, userdata)
 		}
 	}
 }

datasource/datasource.go

@@ -14,12 +14,26 @@
 
 package datasource
 
+import (
+	"net"
+)
+
 type Datasource interface {
 	IsAvailable() bool
 	AvailabilityChanges() bool
 	ConfigRoot() string
-	FetchMetadata() ([]byte, error)
+	FetchMetadata() (Metadata, error)
 	FetchUserdata() ([]byte, error)
 	FetchNetworkConfig(string) ([]byte, error)
 	Type() string
 }
+
+type Metadata struct {
+	PublicIPv4        net.IP
+	PublicIPv6        net.IP
+	PrivateIPv4       net.IP
+	PrivateIPv6       net.IP
+	Hostname          string
+	SSHPublicKeys     map[string]string
+	NetworkConfigPath string
+}

datasource/file/file.go

@@ -17,6 +17,8 @@ package file
 import (
 	"io/ioutil"
 	"os"
+
+	"github.com/coreos/coreos-cloudinit/datasource"
 )
 
 type localFile struct {
@@ -40,8 +42,8 @@ func (f *localFile) ConfigRoot() string {
 	return ""
 }
 
-func (f *localFile) FetchMetadata() ([]byte, error) {
-	return []byte{}, nil
+func (f *localFile) FetchMetadata() (datasource.Metadata, error) {
+	return datasource.Metadata{}, nil
 }
 
 func (f *localFile) FetchUserdata() ([]byte, error) {

datasource/metadata/cloudsigma/server_context.go

@@ -24,6 +24,8 @@ import (
 	"os"
 	"strings"
 
+	"github.com/coreos/coreos-cloudinit/datasource"
+
 	"github.com/coreos/coreos-cloudinit/Godeps/_workspace/src/github.com/cloudsigma/cepgo"
 )
 
@@ -69,7 +71,7 @@ func (_ *serverContextService) Type() string {
 	return "server-context"
 }
 
-func (scs *serverContextService) FetchMetadata() ([]byte, error) {
+func (scs *serverContextService) FetchMetadata() (metadata datasource.Metadata, err error) {
 	var (
 		inputMetadata struct {
 			Name string            `json:"name"`
@@ -88,48 +90,41 @@ func (scs *serverContextService) FetchMetadata() ([]byte, error) {
 				} `json:"vlan"`
 			} `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 []byte
 	)
 
-	rawMetadata, err := scs.client.FetchRaw("")
-	if err != nil {
-		return []byte{}, err
+	if rawMetadata, err = scs.client.FetchRaw(""); err != nil {
+		return
 	}
 
-	err = json.Unmarshal(rawMetadata, &inputMetadata)
-	if err != nil {
-		return []byte{}, err
+	if err = json.Unmarshal(rawMetadata, &inputMetadata); err != nil {
+		return
 	}
 
 	if inputMetadata.Name != "" {
-		outputMetadata.Hostname = inputMetadata.Name
+		metadata.Hostname = inputMetadata.Name
 	} else {
-		outputMetadata.Hostname = inputMetadata.UUID
+		metadata.Hostname = inputMetadata.UUID
 	}
 
+	metadata.SSHPublicKeys = map[string]string{}
 	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
+		metadata.SSHPublicKeys[splitted[len(splitted)-1]] = key
 	}
 
 	for _, nic := range inputMetadata.Nics {
 		if nic.IPv4Conf.IP.UUID != "" {
-			outputMetadata.PublicIPv4 = nic.IPv4Conf.IP.UUID
+			metadata.PublicIPv4 = net.ParseIP(nic.IPv4Conf.IP.UUID)
 		}
 		if nic.VLAN.UUID != "" {
 			if localIP, err := scs.findLocalIP(nic.Mac); err == nil {
-				outputMetadata.LocalIPv4 = localIP
+				metadata.PrivateIPv4 = localIP
 			}
 		}
 	}
 
-	return json.Marshal(outputMetadata)
+	return
 }
 
 func (scs *serverContextService) FetchUserdata() ([]byte, error) {
@@ -154,14 +149,14 @@ func (scs *serverContextService) FetchNetworkConfig(a string) ([]byte, error) {
 	return nil, nil
 }
 
-func (scs *serverContextService) findLocalIP(mac string) (string, error) {
+func (scs *serverContextService) findLocalIP(mac string) (net.IP, error) {
 	ifaces, err := net.Interfaces()
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	ifaceMac, err := net.ParseMAC(mac)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	for _, iface := range ifaces {
 		if !bytes.Equal(iface.HardwareAddr, ifaceMac) {
@@ -176,12 +171,12 @@ func (scs *serverContextService) findLocalIP(mac string) (string, error) {
 			switch ip := addr.(type) {
 			case *net.IPNet:
 				if ip.IP.To4() != nil {
-					return ip.IP.To4().String(), nil
+					return ip.IP.To4(), nil
 				}
 			}
 		}
 	}
-	return "", errors.New("Local IP not found")
+	return nil, errors.New("Local IP not found")
 }
 
 func isBase64Encoded(field string, userdata map[string]string) bool {

datasource/metadata/cloudsigma/server_context_test.go

@@ -15,7 +15,7 @@
 package cloudsigma
 
 import (
-	"encoding/json"
+	"net"
 	"reflect"
 	"testing"
 )
@@ -44,12 +44,6 @@ func (f *fakeCepgoClient) FetchRaw(key string) ([]byte, error) {
 }
 
 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
@@ -114,24 +108,20 @@ func TestServerContextFetchMetadata(t *testing.T) {
 		"uuid": "20a0059b-041e-4d0c-bcc6-9b2852de48b3"
 	}`)
 
-	metadataBytes, err := scs.FetchMetadata()
+	metadata, 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" {
+	if metadata.SSHPublicKeys["john@doe"] != "ssh-rsa AAAAB3NzaC1yc2E.../hQ5D5 john@doe" {
 		t.Error("Public SSH Keys are not being read properly")
 	}
 
-	if metadata.PublicIPv4 != "31.171.251.74" {
+	if !metadata.PublicIPv4.Equal(net.ParseIP("31.171.251.74")) {
 		t.Errorf("Public IP is not 31.171.251.74 but %s instead", metadata.PublicIPv4)
 	}
 }

datasource/metadata/digitalocean/metadata.go

@@ -16,8 +16,10 @@ package digitalocean
 
 import (
 	"encoding/json"
+	"net"
 	"strconv"
 
+	"github.com/coreos/coreos-cloudinit/datasource"
 	"github.com/coreos/coreos-cloudinit/datasource/metadata"
 )
 
@@ -68,45 +70,43 @@ 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
+func (ms *metadataService) FetchMetadata() (metadata datasource.Metadata, err error) {
+	var data []byte
+	var m Metadata
+
+	if data, err = ms.FetchData(ms.MetadataUrl()); err != nil || len(data) == 0 {
+		return
+	}
+	if err = json.Unmarshal(data, &m); err != nil {
+		return
 	}
 
-	var metadata Metadata
-	if err := json.Unmarshal(data, &metadata); err != nil {
-		return []byte{}, err
+	ms.interfaces = m.Interfaces
+	ms.dns = m.DNS
+
+	if len(m.Interfaces.Public) > 0 {
+		if m.Interfaces.Public[0].IPv4 != nil {
+			metadata.PublicIPv4 = net.ParseIP(m.Interfaces.Public[0].IPv4.IPAddress)
+		}
+		if m.Interfaces.Public[0].IPv6 != nil {
+			metadata.PublicIPv6 = net.ParseIP(m.Interfaces.Public[0].IPv6.IPAddress)
+		}
+	}
+	if len(m.Interfaces.Private) > 0 {
+		if m.Interfaces.Private[0].IPv4 != nil {
+			metadata.PrivateIPv4 = net.ParseIP(m.Interfaces.Private[0].IPv4.IPAddress)
+		}
+		if m.Interfaces.Private[0].IPv6 != nil {
+			metadata.PrivateIPv6 = net.ParseIP(m.Interfaces.Private[0].IPv6.IPAddress)
+		}
+	}
+	metadata.Hostname = m.Hostname
+	metadata.SSHPublicKeys = map[string]string{}
+	for i, key := range m.PublicKeys {
+		metadata.SSHPublicKeys[strconv.Itoa(i)] = key
 	}
 
-	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)
+	return
 }
 
 func (ms metadataService) FetchNetworkConfig(filename string) ([]byte, error) {

datasource/metadata/digitalocean/metadata_test.go

@@ -15,10 +15,12 @@
 package digitalocean
 
 import (
-	"bytes"
 	"fmt"
+	"net"
+	"reflect"
 	"testing"
 
+	"github.com/coreos/coreos-cloudinit/datasource"
 	"github.com/coreos/coreos-cloudinit/datasource/metadata"
 	"github.com/coreos/coreos-cloudinit/datasource/metadata/test"
 	"github.com/coreos/coreos-cloudinit/pkg"
@@ -36,7 +38,7 @@ func TestFetchMetadata(t *testing.T) {
 		root         string
 		metadataPath string
 		resources    map[string]string
-		expect       []byte
+		expect       datasource.Metadata
 		clientErr    error
 		expectErr    error
 	}{
@@ -81,7 +83,14 @@ func TestFetchMetadata(t *testing.T) {
   }
 }`,
 			},
-			expect: []byte(`{"hostname":"","public-ipv4":"192.168.1.2","public-ipv6":"fe00::","public_keys":{"0":"publickey1","1":"publickey2"}}`),
+			expect: datasource.Metadata{
+				PublicIPv4: net.ParseIP("192.168.1.2"),
+				PublicIPv6: net.ParseIP("fe00::"),
+				SSHPublicKeys: map[string]string{
+					"0": "publickey1",
+					"1": "publickey2",
+				},
+			},
 		},
 		{
 			clientErr: pkg.ErrTimeout{Err: fmt.Errorf("test error")},
@@ -99,8 +108,8 @@ func TestFetchMetadata(t *testing.T) {
 		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)
+		if !reflect.DeepEqual(tt.expect, metadata) {
+			t.Fatalf("bad fetch (%q): want %#q, got %#q", tt.resources, tt.expect, metadata)
 		}
 	}
 }

datasource/metadata/ec2/metadata.go

@@ -17,10 +17,11 @@ package ec2
 import (
 	"bufio"
 	"bytes"
-	"encoding/json"
 	"fmt"
+	"net"
 	"strings"
 
+	"github.com/coreos/coreos-cloudinit/datasource"
 	"github.com/coreos/coreos-cloudinit/datasource/metadata"
 	"github.com/coreos/coreos-cloudinit/pkg"
 )
@@ -40,59 +41,57 @@ func NewDatasource(root string) *metadataService {
 	return &metadataService{metadata.NewDatasource(root, apiVersion, userdataPath, metadataPath)}
 }
 
-func (ms metadataService) FetchMetadata() ([]byte, error) {
-	attrs := make(map[string]interface{})
+func (ms metadataService) FetchMetadata() (datasource.Metadata, error) {
+	metadata := datasource.Metadata{}
+
 	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)
+				return metadata, fmt.Errorf("malformed public key: %q", keyname)
 			}
 			keyIDs[tokens[1]] = tokens[0]
 		}
 
-		keys := make(map[string]string)
+		metadata.SSHPublicKeys = 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
+				return metadata, err
 			}
-			keys[name] = sshkey
+			metadata.SSHPublicKeys[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
+		return metadata, err
 	}
 
 	if hostname, err := ms.fetchAttribute(fmt.Sprintf("%s/hostname", ms.MetadataUrl())); err == nil {
-		attrs["hostname"] = strings.Split(hostname, " ")[0]
+		metadata.Hostname = strings.Split(hostname, " ")[0]
 	} else if _, ok := err.(pkg.ErrNotFound); !ok {
-		return nil, err
+		return metadata, err
 	}
 
 	if localAddr, err := ms.fetchAttribute(fmt.Sprintf("%s/local-ipv4", ms.MetadataUrl())); err == nil {
-		attrs["local-ipv4"] = localAddr
+		metadata.PrivateIPv4 = net.ParseIP(localAddr)
 	} else if _, ok := err.(pkg.ErrNotFound); !ok {
-		return nil, err
+		return metadata, err
 	}
 
 	if publicAddr, err := ms.fetchAttribute(fmt.Sprintf("%s/public-ipv4", ms.MetadataUrl())); err == nil {
-		attrs["public-ipv4"] = publicAddr
+		metadata.PublicIPv4 = net.ParseIP(publicAddr)
 	} else if _, ok := err.(pkg.ErrNotFound); !ok {
-		return nil, err
+		return metadata, 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,
-		}
+	if contentPath, err := ms.fetchAttribute(fmt.Sprintf("%s/network_config/content_path", ms.MetadataUrl())); err == nil {
+		metadata.NetworkConfigPath = contentPath
 	} else if _, ok := err.(pkg.ErrNotFound); !ok {
-		return nil, err
+		return metadata, err
 	}
 
-	return json.Marshal(attrs)
+	return metadata, nil
 }
 
 func (ms metadataService) Type() string {

datasource/metadata/ec2/metadata_test.go

@@ -15,11 +15,12 @@
 package ec2
 
 import (
-	"bytes"
 	"fmt"
+	"net"
 	"reflect"
 	"testing"
 
+	"github.com/coreos/coreos-cloudinit/datasource"
 	"github.com/coreos/coreos-cloudinit/datasource/metadata"
 	"github.com/coreos/coreos-cloudinit/datasource/metadata/test"
 	"github.com/coreos/coreos-cloudinit/pkg"
@@ -145,7 +146,7 @@ func TestFetchMetadata(t *testing.T) {
 		root         string
 		metadataPath string
 		resources    map[string]string
-		expect       []byte
+		expect       datasource.Metadata
 		clientErr    error
 		expectErr    error
 	}{
@@ -169,7 +170,13 @@ func TestFetchMetadata(t *testing.T) {
 				"/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"}}`),
+			expect: datasource.Metadata{
+				Hostname:          "host",
+				PrivateIPv4:       net.ParseIP("1.2.3.4"),
+				PublicIPv4:        net.ParseIP("5.6.7.8"),
+				SSHPublicKeys:     map[string]string{"test1": "key"},
+				NetworkConfigPath: "path",
+			},
 		},
 		{
 			root:         "/",
@@ -183,7 +190,13 @@ func TestFetchMetadata(t *testing.T) {
 				"/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"}}`),
+			expect: datasource.Metadata{
+				Hostname:          "host",
+				PrivateIPv4:       net.ParseIP("1.2.3.4"),
+				PublicIPv4:        net.ParseIP("5.6.7.8"),
+				SSHPublicKeys:     map[string]string{"test1": "key"},
+				NetworkConfigPath: "path",
+			},
 		},
 		{
 			clientErr: pkg.ErrTimeout{Err: fmt.Errorf("test error")},
@@ -199,8 +212,8 @@ func TestFetchMetadata(t *testing.T) {
 		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)
+		if !reflect.DeepEqual(tt.expect, metadata) {
+			t.Fatalf("bad fetch (%q): want %#v, got %#v", tt.resources, tt.expect, metadata)
 		}
 	}
 }

datasource/proc_cmdline/proc_cmdline.go

@@ -20,6 +20,7 @@ import (
 	"log"
 	"strings"
 
+	"github.com/coreos/coreos-cloudinit/datasource"
 	"github.com/coreos/coreos-cloudinit/pkg"
 )
 
@@ -55,8 +56,8 @@ func (c *procCmdline) ConfigRoot() string {
 	return ""
 }
 
-func (c *procCmdline) FetchMetadata() ([]byte, error) {
-	return []byte{}, nil
+func (c *procCmdline) FetchMetadata() (datasource.Metadata, error) {
+	return datasource.Metadata{}, nil
 }
 
 func (c *procCmdline) FetchUserdata() ([]byte, error) {

datasource/url/url.go

@@ -15,6 +15,7 @@
 package url
 
 import (
+	"github.com/coreos/coreos-cloudinit/datasource"
 	"github.com/coreos/coreos-cloudinit/pkg"
 )
 
@@ -40,8 +41,8 @@ func (f *remoteFile) ConfigRoot() string {
 	return ""
 }
 
-func (f *remoteFile) FetchMetadata() ([]byte, error) {
-	return []byte{}, nil
+func (f *remoteFile) FetchMetadata() (datasource.Metadata, error) {
+	return datasource.Metadata{}, nil
 }
 
 func (f *remoteFile) FetchUserdata() ([]byte, error) {

datasource/waagent/waagent.go

@@ -15,13 +15,14 @@
 package waagent
 
 import (
-	"encoding/json"
 	"encoding/xml"
 	"fmt"
 	"io/ioutil"
 	"net"
 	"os"
 	"path"
+
+	"github.com/coreos/coreos-cloudinit/datasource"
 )
 
 type waagent struct {
@@ -46,13 +47,13 @@ func (a *waagent) ConfigRoot() string {
 	return a.root
 }
 
-func (a *waagent) FetchMetadata() ([]byte, error) {
-	metadataBytes, err := a.tryReadFile(path.Join(a.root, "SharedConfig.xml"))
-	if err != nil {
-		return nil, err
+func (a *waagent) FetchMetadata() (metadata datasource.Metadata, err error) {
+	var metadataBytes []byte
+	if metadataBytes, err = a.tryReadFile(path.Join(a.root, "SharedConfig.xml")); err != nil {
+		return
 	}
 	if len(metadataBytes) == 0 {
-		return metadataBytes, nil
+		return
 	}
 
 	type Instance struct {
@@ -74,30 +75,28 @@ func (a *waagent) FetchMetadata() ([]byte, error) {
 		}
 	}
 
-	var metadata SharedConfig
-	if err := xml.Unmarshal(metadataBytes, &metadata); err != nil {
-		return nil, err
+	var m SharedConfig
+	if err = xml.Unmarshal(metadataBytes, &m); err != nil {
+		return
 	}
 
 	var instance Instance
-	for _, i := range metadata.Instances.Instances {
-		if i.Id == metadata.Incarnation.Instance {
+	for _, i := range m.Instances.Instances {
+		if i.Id == m.Incarnation.Instance {
 			instance = i
 			break
 		}
 	}
 
-	attrs := map[string]string{
-		"local-ipv4": instance.Address,
-	}
+	metadata.PrivateIPv4 = net.ParseIP(instance.Address)
 	for _, e := range instance.InputEndpoints.Endpoints {
 		host, _, err := net.SplitHostPort(e.LoadBalancedPublicAddress)
 		if err == nil {
-			attrs["public-ipv4"] = host
+			metadata.PublicIPv4 = net.ParseIP(host)
 			break
 		}
 	}
-	return json.Marshal(attrs)
+	return
 }
 
 func (a *waagent) FetchUserdata() ([]byte, error) {

datasource/waagent/waagent_test.go

@@ -15,10 +15,11 @@
 package waagent
 
 import (
-	"encoding/json"
+	"net"
 	"reflect"
 	"testing"
 
+	"github.com/coreos/coreos-cloudinit/datasource"
 	"github.com/coreos/coreos-cloudinit/datasource/test"
 )
 
@@ -26,26 +27,23 @@ func TestFetchMetadata(t *testing.T) {
 	for _, tt := range []struct {
 		root     string
 		files    test.MockFilesystem
-		metadata map[string]string
+		metadata datasource.Metadata
 	}{
 		{
-			"/",
-			test.MockFilesystem{},
-			nil,
+			root:  "/",
+			files: test.MockFilesystem{},
 		},
 		{
-			"/",
-			test.MockFilesystem{"/SharedConfig.xml": ""},
-			nil,
+			root:  "/",
+			files: test.MockFilesystem{"/SharedConfig.xml": ""},
 		},
 		{
-			"/var/lib/waagent",
-			test.MockFilesystem{"/var/lib/waagent/SharedConfig.xml": ""},
-			nil,
+			root:  "/var/lib/waagent",
+			files: test.MockFilesystem{"/var/lib/waagent/SharedConfig.xml": ""},
 		},
 		{
-			"/var/lib/waagent",
-			test.MockFilesystem{"/var/lib/waagent/SharedConfig.xml": `<?xml version="1.0" encoding="utf-8"?>
+			root: "/var/lib/waagent",
+			files: test.MockFilesystem{"/var/lib/waagent/SharedConfig.xml": `<?xml version="1.0" encoding="utf-8"?>
 <SharedConfig version="1.0.0.0" goalStateIncarnation="1">
   <Deployment name="c8f9e4c9c18948e1bebf57c5685da756" guid="{1d10394f-c741-4a1a-a6bb-278f213c5a5e}" incarnation="0" isNonCancellableTopologyChangeEnabled="false">
     <Service name="core-test-1" guid="{00000000-0000-0000-0000-000000000000}" />
@@ -82,25 +80,19 @@ func TestFetchMetadata(t *testing.T) {
     </Instance>
   </Instances>
 </SharedConfig>`},
-			map[string]string{
-				"local-ipv4":  "100.73.202.64",
-				"public-ipv4": "191.239.39.77",
+			metadata: datasource.Metadata{
+				PrivateIPv4: net.ParseIP("100.73.202.64"),
+				PublicIPv4:  net.ParseIP("191.239.39.77"),
 			},
 		},
 	} {
 		a := waagent{tt.root, tt.files.ReadFile}
-		metadataBytes, err := a.FetchMetadata()
+		metadata, err := a.FetchMetadata()
 		if err != nil {
 			t.Fatalf("bad error for %q: want %v, got %q", tt, nil, err)
 		}
-		var metadata map[string]string
-		if len(metadataBytes) > 0 {
-			if err := json.Unmarshal(metadataBytes, &metadata); err != nil {
-				panic(err)
-			}
-		}
 		if !reflect.DeepEqual(tt.metadata, metadata) {
-			t.Fatalf("bad metadata for %q: want %q, got %q", tt, tt.metadata, metadata)
+			t.Fatalf("bad metadata for %q: want %#v, got %#v", tt, tt.metadata, metadata)
 		}
 	}
 }