add restore item action to update PVC selected-node annotation

[mynktl]

This change solve below issue

If backed-up persistentvolumeclaims resource has an annotation of selected-node(volume.kubernetes.io/selected-node) and the given node doesn't exist in destination cluster, where the restore is triggered, then restore will stuck InProgress state.

Approach
This restoreItemAction works for persistentvolumeclaims resource having an annotation volume.kubernetes.io/selected-node.

If node-mapping for the given node exists in configMap(in velero installation namespace, with label selector velero.io/plugin-config,velero.io/change-pvc-node=RestoreItemAction), then the plugin will update the PVC annotation with new node and return the updated resource.

If node-mapping for the given node doesn't exist, then the plugin will check for the given node existence. If the given node doesn't exist in the cluster, then the plugin will delete the annotation for selected-node and return the updated persistentvolumeclaims resource.

Signed-off-by: mayank [email protected]

[carlisia]

For the core team: This seems to be the restore side of the same logical issue we are discussing on the backup side in this ticket #1878.

[skriss]

thanks for the PR @mynktl! It looks pretty good, just a few small comments. Two further requests:

• add a changelog (changelogs/unreleased/2377-mynktl) with a brief description of the change
• update site/docs/master/restore-reference.md with info about this plugin - you can use the "Changing PV/PVC Storage Classes" section as a template

[mynktl]

Hi @skriss
Thanks for the review comments.
I've updated the PR with the changes you suggested. PTAL.

• add a changelog (changelogs/unreleased/2377-mynktl) with a brief description of the change

• update site/docs/master/restore-reference.md with info about this plugin - you can use the "Changing PV/PVC Storage Classes" section as a template

Thanks!

[skriss]

thanks for the updates @mynktl, LGTM! We'll just need one other reviewer.

[carlisia]

👍 and thanks for the tests!

[blackpiglet]

According to my test on k8s v1.22, without this plugin, the restore can still work.
The logic in volume controller can remove the select-node annotation from PVC, if the node specified by annotation not found in the cluster, and reconcile for another try.

https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/volume/persistentvolume/pv_controller.go#L1597-L1616

But I think this plugin's code still can be useful in some cases, of course, although it's not mandatory for restore to work.