Unable to restore a longhorn volume

[aacebedo]

Hi
I am learning kubernetes and tried to deploy volsync to backup / restore longhorn volumes.
I have a cluster running K3S with a rancher/local-path and longhorn drivers.
Backup using volsync works correctly disregarding the provisioner. However when I try to restore a volume provisioned with longhorn, I am facing issues. When I restore a volume provided by the rancher/local-path driver, everything works correctly.
I prefer to use Direct copy mode instead of Snapshots.

When the restore is performed, the PVC that shall receive the data created by volsync gets stuck in pending with the following event from the volsync-controller:

reason: VolSyncPopulatorError
message: >-
  Unable to populate volume: ReplicationDestination latestImage is not a
  volumesnapshot
source:

Here is the ReplicationDestination:

apiVersion: volsync.backube/v1alpha1
kind: ReplicationDestination
metadata:
  annotations:
    meta.helm.sh/release-name: searxng
    meta.helm.sh/release-namespace: cloud-services
  creationTimestamp: '2025-02-02T19:45:08Z'
  generation: 1
  labels:
    app: searxng-9.5.4
    app.kubernetes.io/instance: searxng
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: searxng
    app.kubernetes.io/version: latest
    helm-revision: '1'
    helm.sh/chart: searxng-9.5.4
    helm.toolkit.fluxcd.io/name: searxng
    helm.toolkit.fluxcd.io/namespace: cloud-services
    release: searxng
  name: searxng-config-backup-dest
  namespace: cloud-services
  resourceVersion: '2458632'
  uid: bb8f174b-7180-4718-8a48-449bedbfe693
  selfLink: >-
    /apis/volsync.backube/v1alpha1/namespaces/cloud-services/replicationdestinations/searxng-config-backup-dest
status:
  conditions:
    - lastTransitionTime: '2025-02-02T19:45:17Z'
      message: Waiting for manual trigger
      reason: WaitingForManual
      status: 'False'
      type: Synchronizing
  lastManualSync: restore-once
  lastSyncDuration: 10.189207459s
  lastSyncTime: '2025-02-02T19:45:18Z'
  latestImage:
    apiGroup: ''
    kind: PersistentVolumeClaim
    name: volsync-searxng-config-backup-dest-dest
  latestMoverStatus:
    logs: >-
      restoring snapshot db25c686 of [/data] at 2025-02-02 19:03:20.037078864
      +0000 UTC by root@volsync to .

      Restic completed in 2s
    result: Successful
spec:
  restic:
    accessModes:
      - ReadWriteOnce
    cacheCapacity: 500Mi
    cacheStorageClassName: local-path
    capacity: 500Mi
    cleanupCachePVC: false
    cleanupTempPVC: false
    copyMethod: Direct
    moverSecurityContext:
      fsGroup: 568
      runAsGroup: 0
      runAsUser: 0
    repository: searxng-config-volsync-backup
    storageClassName: local-path
  trigger:
    manual: restore-once

and the PVC created:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: searxng-config
  namespace: cloud-services
  uid: b52dd498-ae5d-4c7a-ab25-97ab36994c31
  resourceVersion: '2447405'
  creationTimestamp: '2025-02-02T19:17:34Z'
  labels:
    app: searxng-9.5.4
    app.kubernetes.io/instance: searxng
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: searxng
    app.kubernetes.io/version: latest
    helm-revision: '1'
    helm.sh/chart: searxng-9.5.4
    helm.toolkit.fluxcd.io/name: searxng
    helm.toolkit.fluxcd.io/namespace: cloud-services
    release: searxng
  annotations:
    meta.helm.sh/release-name: searxng
    meta.helm.sh/release-namespace: cloud-services
    volume.beta.kubernetes.io/storage-provisioner: driver.longhorn.io
    volume.kubernetes.io/storage-provisioner: driver.longhorn.io
  finalizers:
    - kubernetes.io/pvc-protection
  selfLink: /api/v1/namespaces/cloud-services/persistentvolumeclaims/searxng-config
status:
  phase: Pending
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 500Mi
  storageClassName: longhorn
  volumeMode: Filesystem
  dataSource:
    apiGroup: volsync.backube
    kind: ReplicationDestination
    name: searxng-config-backup-dest
  dataSourceRef:
    apiGroup: volsync.backube
    kind: ReplicationDestination
    name: searxng-config-backup-dest

[tesshuflower]

@aacebedo It sounds like you are using the volume populator feature of VolSync (your PVC searxng-config has a dataSourceRef that points to your replicationdestination).

This means volsync will wait for a replication on your replicationdestination to have completed and a latest volume snapshot created. It will only work if you are using copyMode Snapshot as the purpose of the volume populator is to easily populate the snapshot on the replicationdestination into a useable PVC.

If you are using copyMode Direct then you can simply use your destination PVC directly, no need to use the volume populator.

Some more detail: With Direct mode, you probably want to set destinationPVC in your replicationdestination spec in order to tell VolSync what PVC to use (otherwise VolSync will create one for you). That is, create an empty PVC (probaby called searxng-config) and then set your destinationPVC to this PVC.

This exact scenario is the one documented in the restic database example in the docs, take a look particularly at the "Restoring a backup" section, and hopefully it explains it in more detail: https://volsync.readthedocs.io/en/stable/usage/restic/database_example.html

[aacebedo]

Thanks for the answer ! it works. I will add a bug to truecharts as the template does not allow to add the destinationPVC.