Docs: Configuring Kubelet in Cluster API

[killianmuldoon]

What would you like to be added (User Story)?

As a user I would like to understand how to configure Kubelet when deployed in a Cluster API cluster using KCP and CAPBK.

Detailed Description

Currently there's a few different approaches:

1. Write a Kubelet conf using CloudInit files
2. Add Kubelet extraArgs in the KubeadmConfigTemplate
3. Patch kubeletconfiguration using a Kubeadm patch defined in the KubeadmConfigTemplate

The documentation should layout basic examples of each approach, and detail the limitations of each.

Anything else you would like to add?

No response

Label(s) to be applied

/kind feature
/kind documentation

[fabriziopandini]

/triage accepted
/help

[k8s-ci-robot]

@fabriziopandini:
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In response to this:

/triage accepted
/help

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[musaprg]

Hi, I'd like to work on this. Let me try to prepare a PR for it.

/assign
/lifecycle active

[killianmuldoon]

@musaprg - awesome, looking forward to seeing what you come up with!

[musaprg]

I'm considering where I should put the document. I think putting it under https://cluster-api.sigs.k8s.io/tasks/bootstrap/kubeadm-bootstrap.html would be best.

[killianmuldoon]

That makes sense to me.

[guettli]

Please consider this use case: I you want to set system-reserved during the execution of preKubeadmCommands.

The script detects the amount of mem and cpu, and then sets the value accordingly.

[fabriziopandini]

from #8670 (comment)

I prepared several examples for #8425. This would help for this purpose.

https://github.com/musaprg/cluster-api-kubelet-config-examples/blob/a46c8c80aa9b194cfda22747b14eaf4a0b86cca7/clusters/cloudinit/kubeadmcontrolplanetemplate.yaml#L10