[epic] Elemental CAPI Implementation

[anmazzotti]

This epic tracks the progress of the Elemental CAPI Implementation.

The scope is to implement the Cluster and Machine infrastructure provider contracts.

To keep aligned with CAPI conventions and to keep implementation simpler, this will be handled as a separate project: cluster-api-provider-elemental

Experimental CAPI features are out of the scope of the epic.

The first goal is to have a working prototype that can be used with the Kubeadm Bootstrap and Control-Plane providers.

A test Elemental image containing kubeadm and all needed dependencies can be provided initially for a proof of concept.

Since Kubeadm is the reference implementation for these providers, it would be best to have automated testing using it, so that we can compare differences and troubleshoot issues when using the RKE2 or K3s providers.

[anmazzotti]

Linking sub-issues:

Prioritized:

• Elemental CAPI Rancher UI Extension #1102
• Elemental CAPI OS Upgrades #1103
• Elemental CAPI support automatic image builds #1104
• Provide a way to configure the host network rancher-sandbox/cluster-api-provider-elemental#28

Low hanging fruits:

• Elemental CAPI hostname management #1038
• Allow selecting install devices on the Elemental OS Plugin rancher-sandbox/cluster-api-provider-elemental#48
• Upgrade elemental-toolkit version rancher-sandbox/cluster-api-provider-elemental#47
• Collect Host information rancher-sandbox/cluster-api-provider-elemental#52
• Allow usage of Elemental btrfs snapshotter when using the Elemental OSPlugin rancher-sandbox/cluster-api-provider-elemental#72
• Prevent kubelet from starting before the elementalhost has been bootstrapped rancher-sandbox/cluster-api-provider-elemental#77

To reconsider:

• Elemental CAPI controlPlaneEndpoint provisioning #1011