NOTE: This project has been superseded by Ignition and is no longer under active development. Please direct all development efforts to Ignition.
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.
Configuration with cloud-config
A subset of the official cloud-config spec is implemented by coreos-cloudinit.
Additionally, several CoreOS-specific options have been implemented to support interacting with unit files, bootstrapping etcd clusters, and more.
All supported cloud-config parameters are documented here.
The following is an example cloud-config document:
#cloud-config
coreos:
units:
- name: etcd.service
command: start
users:
- name: core
passwd: $1$allJZawX$00S5T756I5PGdQga5qhqv1
write_files:
- path: /etc/resolv.conf
content:, nameserver 192.0.2.2
nameserver 192.0.2.3
Executing a Script
coreos-cloudinit supports executing user-data as a script instead of parsing it as a cloud-config document.
Make sure the first line of your user-data is a shebang and coreos-cloudinit will attempt to execute it:
#!/bin/bash
echo 'Hello, world!'
user-data Field Substitution
coreos-cloudinit will replace the following set of tokens in your user-data with system-generated values., Token, Description, -------------, -----------, $public_ipv4, Public IPv4 address of machine, $private_ipv4, Private IPv4 address of machine, These values are determined by CoreOS based on the given provider on which your machine is running.
Read more about provider-specific functionality in the CoreOS OEM documentation.
For example, submitting the following user-data...
#cloud-config
coreos:
etcd:
addr: $public_ipv4:4001
peer-addr: $private_ipv4:7001
...will result in this cloud-config document being executed:
#cloud-config
coreos:
etcd:
addr: 203.0.113.29:4001
peer-addr: 192.0.2.13:7001
Bugs
Please use the CoreOS issue tracker to report all bugs, issues, and feature requests.