Remove finalizers on CSI snapshot objects

[bobfuru]

BZ1896084
Adds instructions for removing finalizers to support volume snapshot delete operations. Includes note that force option is not sufficient.

[bobfuru]

@huffmanca and @duanwei33 PTAL for technical and QE review. Also, please confirm that this is for 4.7+ only. (CSI Snapshot is GA in 4.7.) Thanks.

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[huffmanca]

I'm very hesitant on including instructions for removing VolumeSnapshot finalizers as the default documentation. What I'd do is:

1. Leave the current instructions alone. These should be sufficient for the majority of use-cases.
2. Add an optional section after the existing instructions. This should say something similar to the following:

While the above instructions satisfy the majority of delete operations, there are some circumstances where the
VolumeSnapshot is not successfully deleted. In this case it is required to remove the existing Finalizers from the
VolumeSnapshot resource for the delete operation to continue....
IMPORTANT: Only remove the Finalizers if you are confident that there are no existing references, from either
PersistentVolumeClaims or VolumeSnapshotContents, to the VolumeSnapshot resource.

Then in this optional section we can include the oc patch and oc delete commands.

[bobfuru]

@huffmanca Thanks for the feedback! I reworked this so that it ends as an optional set of steps to follow if the initial default instructions are not enough. I dropped "it is required/must" wording because it falls in the "optional" step, so hopefully your suggested meaning still remains. PTAL and let me know if this ordering is logical to you.

[duanwei33]

@bobfuru I noticed this section name is Deleting a volume snapshot, so from the user side, we need a common use case and an optional part to introduce this bug fix.
In common part(I think the previous process is not complete), the oc delete command need to be listed to delete volumesnapshot or/and VolumeSnapshotContent, as you mentioned, if the deletionPolicy is "Delete", the VolumeSnapshotContent will be deleted alone with the volumesnapshot; if the deletionPolicy is "Retain", VolumeSnapshotContent will remain and oc delete VolumeSnapshotContent could be introduced here if needed.
After that, we can use the oc patch and oc delete for the exception case.

[bobfuru]

Thanks, @duanwei33! I'm not sure that I fully captured what you are suggesting but could you PTAL and let me know if the ordering and wording make sense with my latest update?

[duanwei33]

Thanks, @duanwei33! I'm not sure that I fully captured what you are suggesting but could you PTAL and let me know if the ordering and wording make sense with my latest update?

Hi @bobfuru, thanks for the update, yes this is what I mean to. Just one comment, deleting volumesnapshotcontent depends on the user requirement in the following section, so do you think the update or something like that is ok?

Delete the volume snapshot:

$ oc delete volumesnapshot <volumesnapshot_name>
Example output
volumesnapshot.snapshot.storage.k8s.io "mysnapshot" deleted

If the deletion policy is Retain and you want to delete volumesnapshotcontent object, enter the following commands:

$ oc delete volumesnapshotcontent <volumesnapshotcontent_name>

[bobfuru]

Hi @bobfuru, thanks for the update, yes this is what I mean to. Just one comment, deleting volumesnapshotcontent depends on the user requirement in the following section, so do you think the update or something like that is ok?

Delete the volume snapshot:

$ oc delete volumesnapshot <volumesnapshot_name>
Example output
volumesnapshot.snapshot.storage.k8s.io "mysnapshot" deleted

If the deletion policy is Retain and you want to delete volumesnapshotcontent object, enter the following commands:

$ oc delete volumesnapshotcontent <volumesnapshotcontent_name>

It's helpful that you pointed out this out. I've made some small tweaks along the lines of your suggestion.

[bobfuru]

@huffmanca and @duanwei33 Could you both PTAL once more and let me know if this looks good? Thanks.

[duanwei33]

/LGTM

[bobfuru]

@huffmanca - Ignore my earlier comment, I think this should be backported to all versions back to 4.5, correct?

[huffmanca]

Just some nitpicks and rewording. Otherwise it looks good to me!

[huffmanca]

@bobfuru ,

In regards to backporting, VolumeSnapshots were introduced as tech preview in OCP 4.4. I think we'd need to backport it through all versions to 4.4.

[openshift-ci-robot]

New changes are detected. LGTM label has been removed.

[bobfuru]

Thanks, @huffmanca!

I made a few small edits to be more in line with your most recent comments. You are correct that CSI snapshot was introduced in 4.4 but now that we're in 4.7 GA, we only support back to 4.5 as 4.4 support has ended.

[bobfuru]

LGTM from @huffmanca via Slack.
@openshift/team-documentation PTAL

[bmcelvee]

This is existing content and might be out of scope of this PR, but we've been avoiding future tense (e.g., will be). I'll leave it up to you if you want to change it. :)

[bobfuru]

Good catch! I :) updated two instances using future tense in this note.

[bmcelvee]

LGTM! Just one optional comment.

[bobfuru]

/cherrypick enterprise-4.8

[bobfuru]

/cherrypick enterprise-4.7

[bobfuru]

/cherrypick enterprise-4.6

[bobfuru]

/cherrypick enterprise-4.5

[openshift-cherrypick-robot]

@bobfuru: new pull request created: #30025

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/cherrypick enterprise-4.8

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[openshift-cherrypick-robot]

@bobfuru: new pull request created: #30026

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/cherrypick enterprise-4.7

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[openshift-cherrypick-robot]

@bobfuru: new pull request created: #30027

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/cherrypick enterprise-4.6

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[openshift-cherrypick-robot]

@bobfuru: new pull request created: #30028

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In response to this:

/cherrypick enterprise-4.5

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