Cloud-init

Post-creation script

A simple example of using a post-creation script, as possible with OpenStack, is as follows:

#cloud-config
password: passw0rd
chpasswd: { expire: False }
ssh_pwauth: True

This will set a password for the login user (differs per image?!) and allow this user to login using ssh.

Force run of cloud-init script

You can just run it like this:

/usr/bin/cloud-init -d init

This runs the cloud init setup with the initial modules. Note: the -d option is for debug.

If want to run all the modules you have to run:

/usr/bin/cloud-init -d modules

Keep in mind that the second time you run these it doesn't do much since it has already run at boot time. To force to run after boot time you can run from the command line:

( cd /var/lib/cloud/ && sudo rm -rf * )

Always run cloud-init scripts

In 11.10, 12.04 and later, you can achieve this by making the 'scripts-user' run 'always'. In /etc/cloud/cloud.cfg you'll see something like:

cloud_final_modules:
 - rightscale_userdata
 - scripts-per-once
 - scripts-per-boot
 - scripts-per-instance
 - scripts-user
 - keys-to-console
 - phone-home
 - final-message

This can be modified after boot, or cloud-config data overriding this stanza can be inserted via user-data. Ie, in user-data you can provide:

#cloud-config
cloud_final_modules:
 - rightscale_userdata
 - scripts-per-once
 - scripts-per-boot
 - scripts-per-instance
 - [scripts-user, always]
 - keys-to-console
 - phone-home
 - final-message

More info

Config drive

Most virtual platforms will provision instances with no root password, so it's necessary to supply a password or key to log in using cloud-init. If you're using a virtualization application without cloud-init support, such as virt-manager or VirtualBox, you can create a simple iso image to provide a key or password to your image when it boots.

To create this iso image, you must first create two text files.

Create a file named meta-data that includes an "instance-id" name and a "local-hostname." For instance:

instance-id: instance0
local-hostname: instance-00

The second file is named user-data, and includes password and key information. For instance:

#cloud-config
password: secrete
chpasswd: {expire: False}
ssh_pwauth: True
ssh_authorized_keys:
  - ssh-rsa AAA...EFus user1@mydomain.com
  - ssh-rsa AAB...RDie user2@mydomain.com

Once you have completed your files, they need to packaged into an ISO image. For instance:

# genisoimage -output instance0-cidata.iso -volid cidata -joliet -rock user-data meta-data

You can boot from this iso image, and the auth details it contains will be passed along to your instance.

For more information about creating these cloud-init iso images, see config-drive.

Automated creation of configdrive

Project at GitLab and output

cloud-init