Connect existing block storage volumes?

[feluxe]

Hi there,

is it possible to use csi-digitalocean to connect a kubernetes pod to an existing block storage volume?

I looked at the docs, examples and the issues, but I couldn't find anything related to this.

[Richard87]

Following (I'm also interested in this, specifically in a recovery, how do I reattach volumes to a new cluster if necessary?)

[feluxe]

I was using the stackpoint digitalocean provisioner before and there you could select an existing volume via VolumeName and VolumeID in a PV. You could add a claimRef to the PV to bind it to a PVC. It worked quite well.

I'd much prefer something like this tho:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: csi-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: do-block-storage
  volumeId: 2478ae4c-c31f-44s8-5242-0a58ac14d085

The same discussion for other digitalocean provisioners:

• https://github.com/StackPointCloud/digitalocean-flex-volume/issues/7
• How to provision an already existing Block Storage PersistentVolume on DigitalOcean? kubernetes-retired/external-storage#668

[fatih]

This is not currently possible with the CSI plugin because there is no way to pass down metadata (i.e annotations). If that would be possible, we could pass down the existing volume name via the PVC, such as:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: csi-pvc
  annotations:
    volumeId: "2478ae4c-c31f-44s8-5242-0a58ac14d085"
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: do-block-storage

Then our CSI plugin could read the annotations and decide not to create a new volume and instead re-use the existing volume.

There is an open issue that tracks this feature in the CSI spec and K8S, see: kubernetes-csi/external-provisioner#86 Until there is an official way of doing this, it's not possible unfortunately.

[firatkucuk]

Any progress about this issue? 'cause don't want to hassle for transferring all my volume content.

[snormore]

I was successful in using existing volumes by following this example https://github.com/digitalocean/csi-digitalocean/blob/master/examples/kubernetes/pod-single-existing-volume/README.md

[firatkucuk]

If it's mature enough, it might be good to see it in the official documentation.