Rack controllers

Region/Rack/Machine communication and high-availability environments Install a rack controller
Configuration for multiple API servers Unregister a rack controller

Region/Rack/Machine communication and high-availability environments

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. Please see Communication for more information about the way that rack controllers communicate with region controllers and machines as well as how to use rack controllers in an HA environment.

Install a rack controller

Installing a rack controller consists of installing the rack controller software and then registering the rack controller with the region API server.

When MAAS installs a rack controller on the same host as the region API server, registration occurs automatically. Automatic registration happens in two types of installations:

  1. Using the Ubuntu Server ISO (see Install from ISO)
  2. Using Ubuntu packages: either the ‘maas’ metapackage or multiple individual packages (see Install from packages)

A rack controller can be installed on a host devoid of a region API server, and registered manually, in one of two ways:

  1. Using the Ubuntu Server ISO (see Install from ISO)
  2. Using the ‘maas-rack-controller’ Ubuntu package (see MAAS CLI - advanced tasks)

Once registered, if this is an extra rack controller, it will appear immediately alongside the primary controller in the web UI and begin to sync with it:

install rackd

See MAAS CLI - advanced tasks for how to list (and confirm) all registered rack controllers with the CLI.

You will need multiple rack controllers to achieve specific types of high availability. See MAAS HA.

If you are using KVM-backed nodes, you must ensure that the new rack controller can communicate with the KVM host. See KVM guest nodes.

Configuration for multiple API servers

Please see Multiple region endpoints in the High availability section for more information about how to add another API server (region endpoint).

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 dropdown (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.