88 lines
2.5 KiB
Markdown
88 lines
2.5 KiB
Markdown
# coreos-cloudinit
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coreos-cloudinit allows a user to customize CoreOS machines by providing either an executable script or a cloud-config document as instance user-data. See below to learn how to use these features.
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## cloud-config
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Only a subset of [cloud-config functionality][cloud-config] is implemented. A set of custom parameters were added to the cloud-config format that are specific to CoreOS.
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[cloud-config]: http://cloudinit.readthedocs.org/en/latest/topics/format.html#cloud-config-data
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### Supported cloud-config Parameters
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#### ssh_authorized_keys
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Provided public SSH keys will be authorized for the `core` user.
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The keys will be named "coreos-cloudinit" by default.
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Override this with the `--ssh-key-name` flag when calling `coreos-cloudinit`.
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### Custom cloud-config Parameters
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#### coreos.etcd.discovery_url
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The value of `coreos.etcd.discovery_url` will be used to discover the instance's etcd peers using the [etcd discovery protocol][disco-proto]. Usage of the [public discovery service][disco-service] is encouraged.
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[disco-proto]: https://github.com/coreos/etcd/blob/master/Documentation/discovery-protocol.md
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[disco-service]: http://discovery.etcd.io
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#### coreos.units
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Arbitrary systemd units may be provided in the `coreos.units` attribute.
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`coreos.units` is a list of objects with the following fields:
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- **name**: string representing unit's name
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- **runtime**: boolean indicating whether or not to persist the unit across reboots. This is analagous to the `--runtime` flag to `systemd enable`.
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- **content**: plaintext string representing entire unit file
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See docker example below.
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## user-data Script
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Simply set your user-data to a script where the first line is a shebang:
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```
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#!/bin/bash
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echo 'Hello, world!'
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```
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## Examples
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### Inject an SSH key, bootstrap etcd, and start fleet
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```
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#cloud-config
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coreos:
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etcd:
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discovery_url: https://discovery.etcd.io/827c73219eeb2fa5530027c37bf18877
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fleet:
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autostart: yes
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ssh_authorized_keys:
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- ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC0g+ZTxC7weoIJLUafOgrm+h...
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```
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### Start a docker container on boot
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```
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#cloud-config
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coreos:
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units:
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- name: docker-redis.service
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content: |
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[Unit]
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Description=Redis container
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Author=Me
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After=docker.service
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[Service]
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Restart=always
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ExecStart=/usr/bin/docker start -a redis_server
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ExecStop=/usr/bin/docker stop -t 2 redis_server
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[Install]
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WantedBy=local.target
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```
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