# CloudInit

Cloud-init is a program "that handles the early initialization of a cloud instance"[^n]. In other words, you can, on a "cloud-init"-ready template VM, pass a lot of data at first boot:

  • setting the hostname
  • add ssh keys
  • automatically grow the file system
  • create users
  • and a lot more!

This tool is pretty standard and used everywhere. A lot of existing cloud templates are using it.

So it means very easily customizing your VM when you create it from a compatible template. It brings you closer to the "instance" principle, like in Amazon cloud or OpenStack.

# Requirements

You only need to use a template of a VM with CloudInit installed inside it. Check this blog post to learn how to install CloudInit.

Note: In XOA 5.31, we changed the cloud-init config drive type from OpenStack to the NoCloud type. This will allow us to pass network configuration to VMs in the future. For 99% of users, including default cloud-init installs, this change will have no effect. However if you have previously modified your cloud-init installation in a VM template to only look for openstack drive types (for instance with the datasource_list setting in /etc/cloud/cloud.cfg) you need to modify it to also look for nocloud.

# Usage

First, select your compatible template (CloudInit ready) and name it:

Then, activate the config drive and insert your SSH key. Or you can also use a custom CloudInit configuration:

CloudInit configuration examples are available here.

You can extend the disk size (in this case, the template disk was 8 GiB originally). We'll extend it to 20GiB:

Finally, create the VM:

Now start the VM and SSH to its IP:

  • the system has the right VM hostname (from VM name)
  • you don't need to use a password to access it (thanks to your SSH key):
$ ssh centos@
[centos@tmp-app1 ~]$

The default cloud-init configuration can allow you to be to be a sudoer directly:

[centos@tmp-app1 ~]$ sudo -s
[root@tmp-app1 centos]#

Check the root file system size: indeed, it was automatically increased to what you need:

[centos@tmp-app1 ~]$ df -h
/dev/xvda1          20G    1,2G   18G   6% /