Volume Snapshots

This procedure shows how to create Persistent Volume Snapshots. Read more about this feature in the official Kubernetes documentation.

Before you begin

The following items and configurations are required for this procedure:

• Kubernetes version 1.19.x or higher

• Konvoy version 1.7.x or higher

• CSI driver that supports volume snapshots

Limitations

• Only some CSI drivers support snapshots if underlying platform supports it

Setup Volume Snapshot Class

As StorageClass provides a way for administrators to describe the “classes” of storage they offer when provisioning a volume, VolumeSnapshotClass provides a way to describe the “classes” of storage when provisioning a volume snapshot. You can read more about the different options in this document.

The VolumeSnapshotClass depends on the infrastructure provider you are using. Refer to the sections below for the appropriate one.

AWS

Refer to the AWS EBS CSI documentation.

cat << EOF | kubectl apply -f -
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshotClass
metadata:
  name: csi-vsc
driver: ebs.csi.aws.com
deletionPolicy: Delete
EOF

Azure

Refer to the Azure CSI documentation.

cat << EOF | kubectl apply -f -
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshotClass
metadata:
  name: csi-vsc
driver: disk.csi.azure.com
deletionPolicy: Delete
parameters:
  incremental: "true"  # available values: "true", "false" ("true" by default)
EOF

GCP

Refer to the GCP CSI documentation.

cat << EOF | kubectl apply -f -
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshotClass
metadata:
  name: csi-vsc
driver: pd.csi.storage.gke.io
deletionPolicy: Delete
EOF

Test Volume Snapshots

1. Create a new PersistentVolumeClaim:

   cat << EOF | kubectl apply -f -
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: snapshot-claim
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 4Gi
   EOF
   

2. Create a sample app using the persistentVolumeClaim:

   cat << EOF | kubectl apply -f -
   apiVersion: v1
   kind: Pod
   metadata:
     name: app
   spec:
     containers:
     - name: app
       image: centos
       command: ["/bin/sh"]
       args: ["-c", "while true; do echo \$(date -u) >> /data/out.txt; sleep 5; done"]
       volumeMounts:
       - name: persistent-storage
         mountPath: /data
     volumes:
     - name: persistent-storage
       persistentVolumeClaim:
         claimName: snapshot-claim
   EOF
   

3. Validate the pod successfully wrote data to the volume. Note the timestamp of the first entry:

   kubectl exec -it app -- cat /data/out.txt
   

   The output should look similar to:

   Tue Aug 18 15:00:58 UTC 2020
   Tue Aug 18 15:01:03 UTC 2020
   Tue Aug 18 15:01:08 UTC 2020
   

4. Create a VolumeSnapshot referencing the PersistentVolumeClaim name:

   cat << EOF | kubectl apply -f -
   apiVersion: snapshot.storage.k8s.io/v1beta1
   kind: VolumeSnapshot
   metadata:
     name: volume-snapshot
   spec:
     volumeSnapshotClassName: csi-vsc
     source:
       persistentVolumeClaimName: snapshot-claim
   EOF
   

5. Wait for the READYTOUSE: true attribute of the VolumeSnapshot:

   kubectl get volumesnapshot volume-snapshot -w
   

6. Delete the existing app and PersistentVolumeClaim:

   kubectl delete pod app && kubectl delete pvc snapshot-claim
   

7. Restore a volume from the snapshot with a PersistentVolumeClaim referencing the VolumeSnapshot in its dataSource:

   cat << EOF | kubectl apply -f -
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: snapshot-restored-claim
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 4Gi
     dataSource:
       name: volume-snapshot
       kind: VolumeSnapshot
       apiGroup: snapshot.storage.k8s.io
   EOF
   

8. Create another sample app using the restored persistentVolumeClaim:

   cat << EOF | kubectl apply -f -
   apiVersion: v1
   kind: Pod
   metadata:
     name: app
   spec:
     containers:
     - name: app
       image: centos
       command: ["/bin/sh"]
       args: ["-c", "while true; do echo \$(date -u) >> /data/out.txt; sleep 5; done"]
       volumeMounts:
       - name: persistent-storage
         mountPath: /data
     volumes:
     - name: persistent-storage
       persistentVolumeClaim:
         claimName: snapshot-restored-claim
   EOF
   

9. Validate the new pod has the restored data by comparing the timestamp of the first entry to that of in step 3:

   kubectl exec -it app -- cat /data/out.txt
   

   The output should look similar to:

   Tue Aug 18 15:00:58 UTC 2020
   Tue Aug 18 15:01:03 UTC 2020
   Tue Aug 18 15:01:08 UTC 2020
   ...
   Tue Aug 18 15:05:40 UTC 2020
   Tue Aug 18 15:05:45 UTC 2020
   

10. Delete the app, PersistentVolumeClaim and VolumeSnapshot :

    kubectl delete pod app && kubectl delete pvc snapshot-restored-claim && kubectl delete volumesnapshot volume-snapshot
    

11. Delete the VolumeSnapshotClass:

    kubectl delete volumesnapshotclass csi-vsc