How to deploy a real-time kernel

Deploying Ubuntu with a real-time kernel using MAAS

This guide walks you through the steps to deploy an Ubuntu machine with a real-time (RT) kernel^. The RT kernel comes with all Ubuntu Pro^ subscriptions for Ubuntu 22.04 LTS.

How the RT kernel gets installed

The RT kernel isn’t directly integrated into MAAS. Instead, cloud-init is used to first deploy a generic kernel. Then cloud-init installs the RT kernel and reboots the machine to enable it. Be aware that after MAAS marks the machine as DEPLOYED, there’ll be a delay while cloud-init completes and the machine reboots.

Here’s the sequence of events:

1. Machine deploys with Ubuntu 22.04 LTS and a generic kernel.
2. Machine reboots.
3. Bootloader instructed to boot from disk.
4. Host requests MAAS for configuration.
5. MAAS sends cloud-init config to host.
6. Cloud-init activates Ubuntu Pro.
7. Ubuntu Pro agent installs the RT kernel.
8. Another reboot to enable the new kernel.
9. System is ready for use.

What you’ll need

1. Valid Ubuntu Pro token (find yours at Ubuntu Pro Dashboard^^*^^).
2. MAAS 3.2 or later with Ubuntu 22.04 LTS images.
3. A host compatible with Ubuntu RT kernel.
4. Internet connection.

Deploying the RT kernel

Perform these steps in the MAAS UI:

1. Enlist and commission the host: Do this as you normally would.

2. Initiate deployment: Select the host and click Deploy.

3. Choose OS and release: Opt for Ubuntu and Ubuntu 22.04 LTS "Jammy Jellyfish".

4. Configure cloud-init: Select Cloud-init user-data and use the following template. Replace YOUR_TOKEN with your valid token.

   #cloud-config
   power_state:
     mode: reboot
   ubuntu_advantage:
     token: YOUR_TOKEN
     enable:
       - esm-infra
       - realtime-kernel
   

5. Start deployment: Click Start deployment for machine.

Verifying the deployment

After deployment, execute these commands on the host to confirm RT kernel activation:

1. Check Pro status

   pro status
   

   You should see realtime-kernel as enabled.

2. Confirm kernel version

   uname -a
   

Your machine should now be up and running with an RT kernel.