add KEP to remove dynamic provisioning from in-tree plugins

[carlory]

• One-line PR description: remove dynamic provisioning from in-tree plugins

• Issue link: In-tree volume plugins remove dynamic provisioning support #4547

• Other comments:

[carlory]

/assign @xing-yang

[xing-yang]

Please add a yaml file for production readiness:
https://github.com/kubernetes/enhancements/tree/master/keps/prod-readiness/sig-storage

You also need to fill out the PRR section:
https://github.com/kubernetes/enhancements/tree/master/keps/NNNN-kep-template#production-readiness-review-questionnaire

[xing-yang]

Are there tests currently using the in-tree hostpath plugin for dynamic provisioning?

[carlory]

No.

For e2e tests, both hostPathDriver and hostPathSymlinkDriver don't implement the storageframework.DynamicPVTestDriver interface in the test/e2e/storage/drivers/in_tree.go.

For unit tests, mockVolumePlugin defined in pkg/controller/volume/persistentvolume/framework_test.go is used.

For intergation tests, FakeVolumePlugin defined in pkg/volume/testing/testing.go is used in test/integration/volume/persistent_volumes_test.go

[jpbetz]

Do we have conformance tests for dynamic provisioning that will need to be removed?

[carlory]

No, this KEP is aimed to remove dynamic provisioning for in-tree volume plugins. But host-path drivers in e2e tests don't implement the storageframework.DynamicPVTestDriver interface.

[carlory]

Some unit and integration tests need to be removed. see #4548 (comment)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: carlory
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[k8s-ci-robot]

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[jpbetz]

Should we add a deprecation feature gate for this change? I.e. add a feature gate that is off-by-default but provides any cluster administrators that run into problems with the feature removal with a way to re-enable it for one release before it is removed permanently?

cc @msau42

[jpbetz]

PRR reviewers discussed this as well. Our general agreement is that deprecations should be feature gated (this means introducing a feature gate specifically to aid the deprecation in this case) to allow for a softer landing: "featuregate disables this soft-removed functionality by default, but you can re-enable for one release by setting this gate. The next release, the gate will locked to removed".

EDIT: @deads2k also pointed out: "where "next release" may end up informed by a future skip level upgrade policy" (note that node skew policy is N-3 compatibility with apiserver)

[jpbetz]

PRR reviewer here, #4548 (review), just wanted to point out that is still open, and would be required for this enhancement, and enhancement freeze is tomorrow.

[carlory]

@jpbetz I have to postpone it to 1.32 because of a personal issue. I will update the KEP according to the feedback when I have time.