How to deploy a real-time kernel

[alexsander-souza]

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This page 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.

The RT kernel is currently in Beta. General availability is coming soon.

RT kernel install

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 will be a delay while cloud-init completes and the machine reboots.

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.

Offline installation of the RT kernel is not supported currently.

RT kernel deployment

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 templates. Replace <ubuntu_pro_token> with your valid token.

   1. cloud-init >= 23.4

    #cloud-config
    ubuntu_advantage:
      token: <ubuntu_pro_token>
      enable:
      - realtime-kernel

2. `cloud-init` < 23.4

    #cloud-config
    package_update: true
    package_upgrade: true
    
    runcmd:
    - pro attach <ubuntu_pro_token>
    - yes | pro enable realtime-kernel

5. Start deployment: Click Start deployment for machine.

Verifying deployment

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

1. Check Pro status

    sudo 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.