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!'