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csi-volume-import.md

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Import volumes into Kubernetes

Use Cases

  • Reinstall Kubernetes or migrate volume from one Kubernetes cluster to another
  • Disaster recovery from backup volume
  • Containerize legacy application

Dependencies

  • Kubernetes v1.15+ (Lower version might work however not tested)
  • Pure CSI driver 5.2.0+
  • Support both FA (raw block and file system) and FB (file system)

Import Guidance

The beauty of volume import feature is that there are no changes or additional annotations to persistent volume objects. Take the scenario of migrating volumes from one Kubernetes cluster to another cluster: users can export persistent volume objects (and persistent volume claim objects) from the old cluster and deploy to a new Kubernetes cluster, with no additional changes.

-Caution: important notes about reclaim policy

Both Delete and Retain reclaim policies are supported on imported volumes, where the reclaim policy is configured in persistent volume object. If users delete a persistent volume claim and the corresponding persistent volume has Delete as reclaim policy, both the persistent volume object and backend volume will be deleted automatically.

If users delete a persistent volume (PV) object before deleting the associated persistent volume claim (PVC) the backend volume will NOT be deleted regardless of the reclaim policy setting for the PV. This is consistent with the behaviour of any dynamically provisioned volume.

If users want to import a volume that was created outside of Kubernetes, persistent volume and persistent volume claim objects can be manually created using the following steps:

  1. Create and deploy a persistent volume object with volumeHandle configured to be the name of the volume in backend, and claimRef to be the name of the persistent volume claim at your choice.

    Here is an example, but more examples can be found at: examples/volumeimport

apiVersion: v1
kind: PersistentVolume
metadata:
  annotations:
    pv.kubernetes.io/provisioned-by: pure-csi
  name: pv-import
spec:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 1Gi
  claimRef:
    apiVersion: v1
    kind: PersistentVolumeClaim
    # TODO: change to the PVC you want to bind this PV.
    # If you don't pre-bind PVC here, the PV might be automatically bound to a PVC by scheduler.
    name: pvc-import
    # Namespace of the PVC
    namespace: default
  csi:
    driver: pure-csi
    # TODO: change to the volume name in backend.
    # Volume with any name that exists in backend can be imported, and will not be renamed.
    volumeHandle: ttt-pvc-a90d7d5f-da6c-44db-a306-a4cc122f9dd3
    volumeAttributes:
      backend: file
  # TODO: configure your desired reclaim policy,
  # Use Retain if you don't want your volume to get deleted when the PV is deleted.
  persistentVolumeReclaimPolicy: Delete
  storageClassName: pure-file
  volumeMode: Filesystem

  1. Create and deploy a persistent volume claim object with volumeName configured to the persistent volume created at step 1.

    Here is an example, but more examples can be found at: examples/volumeimport

apiVersion: "v1"
kind: "PersistentVolumeClaim"
metadata:
  name: pvc-import
spec:
  accessModes:
    - "ReadWriteOnce"
  resources:
    requests:
      storage: "1Gi"
  # Note: These two fields are not required for pre-bound PV.
  # storageClassName: pure-block
  # volumeMode: Filesystem

  # TODO: Change to the name of the imported PV.
  volumeName: pv-import
  1. Use the persistent volume claim.
 apiVersion: v1
 kind: Pod
 metadata:
   name: nginx
 spec:
   # Specify a volume that uses the claim defined in pvc.yaml
   volumes:
   - name: pure-vol
     persistentVolumeClaim:
         claimName: pvc-import
   containers:
   - name: nginx
     image: nginx
     # Configure a mount for the volume We define above
     volumeMounts:
     - name: pure-vol
       mountPath: /data
     ports:
     - containerPort: 80