Rack controllers (deb/2.9/CLI)

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A rack controller can connect to multiple VLANs, each from a different network interface. This configuration provides a scaling factor that can help as a network architecture grows in size.

Five questions you may have:

  1. How does MAAS communication work?
  2. How do I install a rack controller?
  3. How do I list rack controllers?
  4. How do I configure MAAS for multiple API servers?
  5. How do I unregister a rack controller?

Install a rack controller

To install and register a rack controller with the MAAS:

sudo apt install maas-rack-controller
sudo maas-rack register

The register command is not required when you are adding a rack controller to a system that already houses an API server.

MAAS will ask for the URL of the region API server. If you provide a hostname, ensure it is resolvable. Next, MAAS will prompt you for the secret key, stored in file /var/lib/maas/secret on the API server.

Based on the above, then, we could have also entered:

sudo maas-rack register --url http://10.5.1.5:5240/MAAS \
    --secret fa847000e7cb681101d26e3477e6e39e

List rack controllers

You can also list and confirm all registered rack controllers:

maas $PROFILE rack-controllers read | grep hostname | cut -d '"' -f 4

Note that you will need multiple rack controllers to achieve specific high availability configurations.

If you are using VM nodes, you must ensure that the new rack controller can communicate with the VM host.

Unregister a rack controller

Most likely, you would only “unregister” an extra, unnecessary rack controller. In this case, you need to delete it from the region API server; there is no ‘unregister’ command.

To do so, navigate to the ‘Controllers’ page of the web UI. Enter the controller’s page by clicking on the machine you want to delete and select ‘Delete’ from the drop-down (and then ‘Delete controller’). MAAS will do the right thing if the controller is used for DHCP HA; that is, the DHCP HA needs to be disabled.

Although similar, this is not the same as deletion. Here, you are deleting a machine that is a part of MAAS itself.

Unless you remove the software on this machine, rebooting it will cause the machine to re-instate itself as a rack controller. This behaviour may change with future versions of MAAS.