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