How to exclude specific CSI volumes from backup?

[Zalfsten]

I have the same task as #7746: I would like to use the backup facilities of by PostgreSQL operator instead of velero to backup the persistent volume of my database.

It's no problem to introduce a backup hook to trigger an operator backup, but still velero will also create a normal CSI snapshot and store it in S3 -- which wastes a lot resources. How do I exclude my PostgreSQL volumes from backup?

I'm using the builtin velero CSI plugin for volume snapshots.

The annotation backup.velero.io/backup-volumes-excludes has no effect for me. It could be that it's not evaluated by the CSI plugin.

Any ideas how to fix this?

[sseago]

backup.velero.io/backup-volumes-excludes wouldn't help you -- that is intended to opt out of fs-backup (when that's the default) and use snapshots instead.

You might be able to use volume policies (applying the skip policy) if the available filters are able to narrow down to just the PostgresQL volumes, although I don't know if that's enough to uniquely describe the volumes of interest in your case. Here's the doc for that:
https://velero.io/docs/main/resource-filtering/#resource-policies

[Zalfsten]

Thanks for your answer, @sseago

I've thought about that. I think I could use this to exclude the backup of the PostgreSQL PVCs, but actually I need them for a full restore. I would like to backup all kubernetes manifests -- just not the PostgreSQL volume contents.

Actually I do not understand good enough, how velero works internally. When does velero trigger the CSI plugin? -- When it encounters a PVC to backup? Or when it encounters a PV? Or maybe a Pod?
In case it's the PV, I could exclude the PVs from backup, because they get created automatically when I create/restore a PVC...

[Zalfsten]

Oh... maybe it' possible... I wasn't aware that there is something like the skip policy. I will try out