A volume snapshot is a copy of the state taken from a PVC in the Kubernetes cluster. It is a useful resource for bringing up a stateful application using existing data. Let's perform the following steps to create a volume snapshot using CSI:

1. Create a PVC or select an existing one. In our recipe, we'll use the AWS EBS CSI driver and the aws-csi-ebs storage class we created in Chapter 5, Preparing for Stateful Workloads, in the Installing an EBS CSI driver to manage EBS volumes recipe:

$ cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: csi-ebs-pvc
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: aws-csi-ebs
  resources:
    requests:
      storage: 4Gi
EOF

2. Create a pod that will write to the /data/out.txt file inside the PersistentVolume (PV):

$ 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: csi-ebs-pvc
EOF

3. Create a VolumeSnapshotClass. Make sure that the snapshot provider is set to your CSI driver name. In this recipe, this is ebs.csi.aws.com:

$ cat <<EOF | kubectl apply -f -
apiVersion: snapshot.storage.k8s.io/v1alpha1
kind: VolumeSnapshotClass
metadata:
  name: csi-ebs-vsc
snapshotter: ebs.csi.aws.com
EOF

4. A PVC must be created using the CSI driver of a storage vendor. In our recipe, we will use the PVC we created in the Installing EBS CSI driver to manage EBS volumes recipe. Now, create a VolumeSnapshot using the PVC name (csi-ebs-pvc) we set in Step 1:

$ cat <<EOF | kubectl apply -f -
apiVersion: snapshot.storage.k8s.io/v1alpha1
kind: VolumeSnapshot
metadata:
  name: ebs-volume-snapshot
spec:
  snapshotClassName: csi-ebs-vsc
  source:
    name: csi-ebs-pvc
    kind: PersistentVolumeClaim
EOF

5. List the Volume Snapshots:

$ kubectl get volumesnapshot
NAME AGE
ebs-volume-snapshot 18s

6. Validate that the status is Ready To Use: true when checking the output of the following command:

$ kubectl describe volumesnapshot ebs-volume-snapshot