CloudInit

CloudInit support is available from 4.11 release

Cloud-init is a program "that handles 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 hostname
  • add ssh keys
  • grow automatically 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 customizing very easily your VM when you create it from a compatible template. It brings you closer to the "instance" principle, like in Amazon cloud or OpenStack.

Requirement

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.

Usage

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

Then, activate the config drive and put 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):

Finally, create the VM:

Now start the VM and SSH on its IP:

  • the system got the right VM hostname (from VM name)
  • you don't have to use a password to access it (thanks to your SSH key):
$ ssh centos@192.168.100.226
[centos@tmp-app1 ~]$

The default cloud-init configuration could 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 grown to what you need:

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

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