Deprecate kubelet "enable-controller-attach-detach" option

[msau42]

Is this a BUG REPORT or FEATURE REQUEST?:
/kind feature
@kubernetes/sig-storage-feature-requests

What happened:
Are there any use cases where we still need to support kubelet doing the attach/detach? If not, let's deprecate this field and eventually remove it.

[fejta-bot]

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/lifecycle stale

[msau42]

/remove-lifecycle stale

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/lifecycle stale

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[wackxu]

/remove-lifecycle stale

[wackxu]

according to #20262,

Since rolling upgrades are only supported for up to two Kubernetes releases, after two releases this rolling upgrade logic can be removed. That means the volume.temporary.kubernetes.io/controller-managed annotation can be retirered and the controller can operate on all nodes by default (ignore the annotation).

I think we can remove the logic for kubelet doing the attach/detach.

[jsafrane]

It's lengthy process to deprecate something. https://kubernetes.io/docs/reference/using-api/deprecation-policy/

With the old policy (when we introduced the annotation), it would fall into

Rule #7: Deprecated behaviors must function for no less than 1 year after their announced deprecation.

But with the new one, it seems impossible to remove the annotation:

The following rules govern the deprecation of elements of the API. This includes:

• Annotations on REST resources, including “beta” annotations but not including “alpha” annotations.

Could we get an exception in this case?

[msau42]

Discussed with @saad-ali a little, he says there are users that still need this flag so I'm not sure if we can ever remove it. If we cannot remove it and need to support it forever, then maybe we need to at least document the limitations of using this, and test this configuration as well.

[Zhuvikin]

I think this flag is still needed at least for attach/detach operations in case when some static pod needs volume and controller isn't up yet. My case is to use cinder volume plugin in static pod definition like follows.

volumes:
  - cinder:
      fsType: "ext4"
      volumeID: "1234678-90-1234-5678-90123456789"
    name: data

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/close

[msau42]

/reopen
/lifecycle frozen

[k8s-ci-robot]

@msau42: Reopened this issue.

In response to this:

/reopen
/lifecycle frozen

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[msau42]

This is an untested configuration and as we're adding more features and designing around AD controller/kubelet coordination for things like migration, this functionality is bound to get broken.

We should think about how to support the static pod scenario outlined above considering the move towards CSI and eventually removing all in-tree plugin code. Many CSI features today depend on K8s api objects and won't work in a static pod/master bootstrapping scenario.

[bertinatto]

@msau42 @jsafrane since we are migrating to CSI and this option is mandatory for that use case, is there a way we can deprecate this now?