🐛 Skip draining failed DaemonSet pods to prevent recreation loops

[liuxu623]

What this PR does / why we need it:

In scenarios where nodes experience DiskPressure, DaemonSet pods may be evicted and enter Failed state. When deleting Machines, cluster-api attempts to delete these failed pods, but this triggers DaemonSet to create new pods which can then be evicted again due to persistent DiskPressure, creating an infinite loop.

/area machine

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[k8s-ci-robot]

Hi @liuxu623. Thanks for your PR.

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[chrischdi]

Could you please provide more information (logs, yaml Data etc.) to gather further information?

Afaik, daemonset pods get ignored during drain.
That is also mentioned here https://cluster-api.sigs.k8s.io/tasks/automated-machine-management/machine_deletions#node-drain

[liuxu623]

Could you please provide more information (logs, yaml Data etc.) to gather further information?

Afaik, daemonset pods get ignored during drain. That is also mentioned here https://cluster-api.sigs.k8s.io/tasks/automated-machine-management/machine_deletions#node-drain

https://github.com/kubernetes-sigs/cluster-api/blob/v1.10.4/internal/controllers/machine/drain/filters.go#L215-L218

	// Any finished pod can be removed.
	if pod.Status.Phase == corev1.PodSucceeded || pod.Status.Phase == corev1.PodFailed {
		return MakePodDeleteStatusOkay()
	}

For failed daemonSet Pods, cluster-api will still delete them. The timeline roughly goes like this:

1. Delete Machine
2. cluster-api deletes the failed daemonSet Pod
3. daemonSet controller creates a new Pod
4. kubelet evict the new Pod and causes it to become Failed
5. cluster-api deletes the new failed daemonSet Pod
6. ...

cluster-api and the daemonSet controller enter a loop.

[chrischdi]

Ah so its about failed or succeeded daemonset pods. That changes things.

Did you try if MachineDrainRules could help to workaround your issue? (see: https://github.com/kubernetes-sigs/cluster-api/blob/main/docs/proposals/20240930-machine-drain-rules.md )

Just changing the drain behavior might introduce issues for other users.

[liuxu623]

Ah so its about failed or succeeded daemonset pods. That changes things.

Did you try if MachineDrainRules could help to workaround your issue? (see: https://github.com/kubernetes-sigs/cluster-api/blob/main/docs/proposals/20240930-machine-drain-rules.md )

Just changing the drain behavior might introduce issues for other users.

In certain scenarios, such as when a node is under DiskPressure, any DaemonSet Pod may be evicted. This is not an issue specific to any particular DaemonSet but rather stems from node-level abnormalities. In this context, MachineDrainRules may not be applicable.