Register an Unmanaged OS

Normally, the SUSE® Rancher Prime OS Manager Operator manages operating systems that are installed and configured by the SUSE® Rancher Prime OS Manager Toolkit.
For example, in order to automate OS installation, upgrade, and reset, the elemental-register relies on the elemental CLI to execute these operations.

However, it is also possible to register and provision SUSE® Rancher Prime OS Manager "Toolkitless" systems.

In this scenario, elemental-register needs to be installed on the system.
Optionally, the elemental-system-agent can be installed. Note that without the elemental-system-agent, the SUSE® Rancher Prime OS Manager Operator will not be able to provision any k8s cluster on the machine. In this case the SUSE® Rancher Prime OS Manager Operator can only be used for OS Inventory purposes only.

Finally, on the management cluster, the MachineRegistration must enable the spec.config.elemental.registration.no-toolkit flag.

Once no-toolkit is enabled on the MachineRegistration, and a new registration occurs using elemental-register --install on the system, a new MachineInventory will be created on the management cluster:

The MachineInventory will be annotated with the elemental.cattle.io/os.unmanaged: "true" annotation, highlighting that this machine is not managed and has limited functionality.

On the system, upon successful registration, the /etc/rancher/elemental/agent/config.yaml and /var/lib/elemental/agent/elemental_connection.json files are automatically created to configure the elemental-system-agent. The elemental-system-agent component is needed for K8s provisioning and Reset triggers.

When a machine reset is triggered, for example by deleting the MachineInventory directly, the elemental-system-agent will execute a simple reset plan that will create the /var/lib/elemental/.unmanaged_reset sentinel file.
The presence of this file indicates that the machine needs a reset. This may involve stopping services, uninstalling packages, formatting devices, and so on, depending how the machine is customly managed.