Import existing, externally created snapshot into cluster

[stiller-leser]

Hi everybody,

I have started playing around with snapshotting. My usecase is to import an existing snapshot into the cluster (it has been created externaly, not from a pv in the cluster). My current attempt with these two configurations fails with the snapshot source is not specified when creating the VolumeSnapshot:

apiVersion: snapshot.storage.k8s.io/v1alpha1
kind: VolumeSnapshotContent
metadata:
  name: my-own-snapshot-content
  namespace: default
spec:
  csiVolumeSnapshotSource:
    driver: pd.csi.storage.gke.io
    snapshotHandle: projects/my-project/global/snapshots/my-snapshot
  deletionPolicy: Retain
  volumeSnapshotRef:
    kind: VolumeSnapshot
    name: my-own-snapshot-source-pvc
    namespace: default

apiVersion: snapshot.storage.k8s.io/v1alpha1
kind: VolumeSnapshot
metadata:
  name: my-own-snapshot-source-pvc
  namespace: default
spec:
  snapshotClassName: default-snapshot-class
  snapshotContentName: my-own-snapshot-content

( taken from this blog post )

Looking at this code it seems logical.

However, reading through the spec it says for the VolumeSnapshot struct:

// Source has the information about where the snapshot is created from.
// In Alpha version, only PersistentVolumeClaim is supported as the source.
// If not specified, user can create VolumeSnapshotContent and bind it with VolumeSnapshot manually.

This is the part that is confusing me, because the last comment describes what I am trying to do above. I assumed that the PVC created from the referenced VolumeSnapshot could be created from the snapshotHandle defined in the VolumeSnapshotContent. Instead, it seems I need to define an existing PVC in the VolumeSnapshot.

Will my approach become possible in the future (i.e. currently not yet possible, since this is an alpha feature) or is this usecase not intended at all? If not, how else could I do it in Kubernetes (it would of course be possible using the cloud provider sdk).

Best regards,
stiller-leser

P.S. This is related to this question: kubernetes-sigs/gcp-compute-persistent-disk-csi-driver#224

[msau42]

Importing existing snapshot should be possible. It needs more documentation and testing though.
cc @xing-yang @jingxu97

[nrb]

If you're using GKE, I saw this too. It appears to be fixed in v1.1.0 of csi-snapshotter, but GKE's driver currently comes with v1.0.1. See #94

[msau42]

fyi, tracking issue to update snapshotter in pd csi driver: kubernetes-sigs/gcp-compute-persistent-disk-csi-driver#321

[xing-yang]

@stiller-leser The comment "If not specified, user can create VolumeSnapshotContent and bind it with VolumeSnapshot manually" means you can dynamically create a VolumeSnapshot using an already existing snapshot resource. It does not mean you need to define an existing PVC in VolumeSnapshot.

Can you try v1.1.0 or later of csi-snapshotter as suggested by @nrb? Looks like you need to wait for a fix in the PD CSI driver before testing that.

[stiller-leser]

Hi everybody,

you rock! Thank you for getting back to me so quickly - this is awesome. Thanks to the pointer of @nrb I was able to see that I was using an old version of the snapshotter. Updated it and it works 👍

Also @xing-yang - I must have misread this then. Guess that happens if you play around way above your K8s knowledge ;) - Thank you for the explanation!