snapshot

Volume Snapshots

Overview

This driver implements basic volume snapshotting functionality using the external snapshotter sidecar and creates snapshots of BSU volumes using the VolumeSnapshot custom resources.

Prerequisites

1. Kubernetes 1.21 and Later

In Kubernetes versions 1.21 and later, VolumeSnapshotDataSource has been enabled by default. If your cluster is running Kubernetes 1.21 or higher, you do not need to manually set the --feature-gates=VolumeSnapshotDataSource=true flag, as it should already be enabled. The snapshot feature will work out of the box without the need for additional configuration at the API server level.

2. Kubernetes 1.20 and Earlier

In Kubernetes versions 1.20 and earlier, the VolumeSnapshotDataSource feature is not enabled by default, so you would need to manually set the --feature-gates=VolumeSnapshotDataSource=true flag on the API server to enable volume snapshots.

3. Install the Latest CRDs for Volume Snapshotting

You can apply the CRDs (if not already installed) using the following commands:

kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/release-8.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/release-8.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/release-8.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml

This will set up the necessary CRDs for volume snapshotting.

4. Install the Snapshot Controller

The snapshot controller is responsible for managing snapshots in your cluster. You can install it using the following commands:

kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/release-8.0/deploy/kubernetes/snapshot-controller/rbac-snapshot-controller.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/release-8.0/deploy/kubernetes/snapshot-controller/setup-snapshot-controller.yaml

This ensures that the snapshot controller is set up correctly to manage volume snapshots and restorations.

5. Verify the Configuration

After applying the CRDs and deploying the snapshot controller, ensure everything is set up correctly:

kubectl get crds | grep snapshot

6. Ensure the snapshot controller pods are running

kubectl get pods -n kube-system | grep snapshot

7. Check if the VolumeSnapshotClass and VolumeSnapshot resources are available

kubectl get volumesnapshotclass
kubectl get volumesnapshot

Usage

1. Create the StorageClass and VolumeSnapshotClass:

kubectl apply -f specs/classes/

2. Create a sample app and the PersistentVolumeClaim:

kubectl apply -f specs/app/

3. Validate the volume was created and volumeHandle contains an BSU volumeID:

kubectl describe pv

4. Validate the pod successfully wrote data to the volume, taking note of the timestamp of the first entry:

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

5. Create a VolumeSnapshot referencing the PersistentVolumeClaim name:

kubectl apply -f specs/snapshot/

6. Wait for the Ready To Use: true attribute of the VolumeSnapshot:

kubectl describe volumesnapshot.snapshot.storage.k8s.io bsu-volume-snapshot

7. Delete the existing app:

kubectl delete -f specs/app/

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

kubectl apply -f specs/snapshot-restore/

9. Validate the new pod has the restored data by comparing the timestamp of the first entry to that of in step 4:

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

10. Cleanup resources:

kubectl delete -f specs/snapshot-restore
kubectl delete -f specs/snapshot
kubectl delete -f specs/classes