Using volume snapshots

In Google Kubernetes Engine (GKE), you can use the Kubernetes volume snapshot feature for persistent volumes in your GKE clusters.

Volume snapshots let you create a copy of your volume at a specific point in time. You can use this copy to bring a volume back to a prior state or to provision a new volume.

From version 1.17 or later, you can provision and attach volume snapshots with the following components:

Requirements

You must meet the following requirements to use volume snapshots on GKE:

Use a CSI driver that supports snapshots. Snapshots are not supported by the in-tree persistent disk driver. The Compute Engine persistent disk CSI driver is installed by default on new Linux clusters running GKE version 1.18.10-gke.2100 or later, or version 1.19.3-gke.2100 or later. You can also enable the Compute Engine persistent disk CSI driver on an existing cluster. For a list of all CSI drivers that support snapshots, see the "Other features" column in Drivers in the Kubernetes documentation.
Use control plane (master) versions that are GKE versions 1.17 or later. To use the Compute Engine persistent disk CSI Driver, in a VolumeSnapshot, use GKE versions 1.17.6-gke.4 or later.
Have an existing PersistentVolumeClaim to use for a snapshot. The PersistentVolume you use for a snapshot source must be managed by a CSI driver. You can verify that you're using a CSI driver by checking that the PersistentVolume spec has a csi section with driver: pd.csi.storage.gke.io. If the PersistentVolume is dynamically provisioned by the CSI driver as described in the following sections, it's managed by the CSI driver.

Before you begin

Before you start, make sure you have performed the following tasks:

Ensure that you have enabled the Google Kubernetes Engine API.

Enable Google Kubernetes Engine API

Ensure that you have installed the Cloud SDK.

Set up default gcloud settings using one of the following methods:

Using gcloud init, if you want to be walked through setting defaults.
Using gcloud config, to individually set your project ID, zone, and region.

Using gcloud init

If you receive the error One of [--zone, --region] must be supplied: Please specify location, complete this section.

Run gcloud init and follow the directions:
```
gcloud init
```
If you are using SSH on a remote server, use the --console-only flag to prevent the command from launching a browser:
```
gcloud init --console-only
```
Follow the instructions to authorize gcloud to use your Google Cloud account.
Create a new configuration or select an existing one.
Choose a Google Cloud project.
Choose a default Compute Engine zone for zonal clusters or a region for regional or Autopilot clusters.

Note: You can override these default settings in gcloud commands using the --project, --zone, and --region flags.

Using gcloud config

Set your default project ID:
```
gcloud config set project PROJECT_ID
```
If you are working with zonal clusters, set your default compute zone:
```
gcloud config set compute/zone COMPUTE_ZONE
```
If you are working with Autopilot or regional clusters, set your default compute region:
```
gcloud config set compute/region COMPUTE_REGION
```
Update gcloud to the latest version:
```
gcloud components update
```

Note: You can override these default settings in gcloud commands using the --project, --zone, and --region flags.

Creating and using a volume snapshot

The examples in this document show you how to do the following:

Create a PersistentVolumeClaim and Deployment.
Add a file to the PersistentVolume that the Deployment uses.
Create a VolumeSnapshotClass to configure the snapshot.
Create a volume snapshot of the PersistentVolume.
Delete the test file.
Restore the PersistentVolume to the snapshot you created.
Verify that the restoration worked.

To use a volume snapshot, you must complete the following steps:

Create a VolumeSnapshotClass object to specify the CSI driver and deletion policy for your snapshot.
Create a VolumeSnapshot object to request a snapshot of an existing PersistentVolumeClaim.
Reference the VolumeSnapshot in a PersistentVolumeClaim to restore a volume to that snapshot or create a new volume using the snapshot.

Create a PersistentVolumeClaim and a Deployment

To create the PersistentVolumeClaim object, save the following manifest as my-pvc.yaml:
```
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  storageClassName: standard-rwo
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
```
For spec.storageClassName, you can specify any storage class that uses a supported CSI driver. This example uses the standard-rwo storage class installed by default with the Compute Engine persistent disk CSI driver. For more information, refer to Using the Compute Engine persistent disk CSI driver.
Apply the manifest:
```
kubectl apply -f my-pvc.yaml
```

To create a Deployment, save the following manifest as my-deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-app
spec:
  selector:
    matchLabels:
      app: hello-app
  template:
    metadata:
      labels:
        app: hello-app
    spec:
      containers:
      - name: hello-app
        image: google/cloud-sdk:slim
        args: [ "sleep", "3600" ]
        volumeMounts:
        - name: sdk-volume
          mountPath: /usr/share/hello/
      volumes:
      - name: sdk-volume
        persistentVolumeClaim:
          claimName: my-pvc

Apply the manifest:
```
kubectl apply -f my-deployment.yaml
```
Check the status of the Deployment:
```
kubectl get deployment hello-app
```
Note: It might take some time for the Deployment to become ready.

Add a test file to the volume

List the pods in the Deployment:

kubectl get pods -l app=hello-app

The output is similar to the following:

NAME                         READY   STATUS    RESTARTS   AGE
hello-app-6d7b457c7d-vl4jr   1/1     Running   0          2m56s

Create a test file in a Pod:

kubectl exec POD_NAME -- sh -c 'echo "Hello World!" > /usr/share/hello/hello.txt'

Replace POD_NAME with the name of the Pod.

Verify that the file exists:

kubectl exec POD_NAME -- sh -c 'cat /usr/share/hello/hello.txt'

The output is similar to the following:

Hello World!

Create a `VolumeSnapshotClass` object

Create a VolumeSnapshotClass object to specify the CSI driver and deletionPolicy for your volume snapshot. You can reference VolumeSnapshotClass objects when you create VolumeSnapshot objects.

Save the following manifest as volumesnapshotclass.yaml. You can use either API version v1beta1 or v1 depending on the version of GKE on your cluster.
v1beta1
Use the v1beta1 API version for clusters running versions 1.23 or earlier.
```
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshotClass
metadata:
  name: my-snapshotclass
driver: pd.csi.storage.gke.io
deletionPolicy: Delete
```
v1
Use the v1 API version for clusters running versions 1.21 or later.
```
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: my-snapshotclass
driver: pd.csi.storage.gke.io
deletionPolicy: Delete
```
In this example:
- The driver field is the CSI driver to use to provision the snapshot. pd.csi.storage.gke.io uses the Compute Engine persistent disk CSI Driver.
- ThedeletionPolicy field tells GKE what to do with the VolumeSnapshotContent object and the underlying snapshot when the bound VolumeSnapshot object is deleted. Specify Delete to delete the VolumeSnapshotContent object and the underlying snapshot. You can also specify Retain if you want to keep the VolumeSnapshotContent and underlying snapshot.

Apply the manifest:

kubectl apply -f volumesnapshotclass.yaml

Create a VolumeSnapshot

A VolumeSnapshot object is a request for a snapshot of an existing PersistentVolumeClaim object. When you create a VolumeSnapshot object, GKE automatically creates and binds it with a VolumeSnapshotContent object, which is a resource in your cluster like a PersistentVolume object.

Save the following manifest as volumesnapshot.yaml. You can use API version v1beta1 or v1.

v1beta1

Use the v1beta1 API version for clusters running versions 1.23 or earlier.

apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
  name: my-snapshot
spec:
  volumeSnapshotClassName: my-snapshotclass
  source:
    persistentVolumeClaimName: my-pvc

v1

Use the v1 API version for clusters running versions 1.21 or later.

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: my-snapshot
spec:
  volumeSnapshotClassName: my-snapshotclass
  source:
    persistentVolumeClaimName: my-pvc

Apply the manifest:
```
kubectl apply -f volumesnapshot.yaml
```
After you create a volume snapshot, GKE creates a corresponding VolumeSnapshotContent object in the cluster. This object stores the snapshot and bindings of VolumeSnapshot objects. You do not interact with VolumeSnapshotContents objects directly.

To confirm that GKE created the VolumeSnapshotContents object, run the following command:

kubectl get volumesnapshotcontents

The output is similar to the following:

NAME                                               AGE
snapcontent-cee5fb1f-5427-11ea-a53c-42010a1000da   55s

After the volume snapshot content is created, the CSI driver you specified in the VolumeSnapshotClass creates a snapshot on the corresponding storage system. After GKE creates a snapshot on the storage system and binds it to a volume snapshot object on the cluster, the snapshot is ready to use. You can check the status by running the following command:

kubectl get volumesnapshot \
  -o custom-columns='NAME:.metadata.name,READY:.status.readyToUse'

If it's ready to use, the output is similar to the following:

NAME               READY
my-snapshot        true

Delete the test file

Delete the test file you created:

kubectl exec POD_NAME -- sh -c 'rm /usr/share/hello/hello.txt'

Verify that the file no longer exists:

kubectl exec POD_NAME -- sh -c 'cat /usr/share/hello/hello.txt'

The output is similar to the following:

cat: /usr/share/hello/hello.txt: No such file or directory

Restore the volume snapshot

You can reference a VolumeSnapshot in a PersistentVolumeClaim to provision a new volume with data from an existing volume or restore a volume to a state that you captured in the snapshot.

To reference a VolumeSnapshot in a PersistentVolumeClaim, add the dataSource field to your PersistentVolumeClaim.

In this example, you reference the VolumeSnapshot you created in a new PersistentVolumeClaim and update the Deployment to use the new claim.

Save the following manifest as pvc-restore.yaml:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-restore
spec:
  dataSource:
    name: my-snapshot
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
  storageClassName: standard-rwo
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

Apply the manifest:
```
kubectl apply -f pvc-restore.yaml
```

Update my-deployment.yaml to use the new PersistentVolumeClaim:

...
volumes:
- name: my-volume
  persistentVolumeClaim:
    claimName: pvc-restore

Apply the updated manifest:
```
kubectl apply -f my-deployment.yaml
```

Check that the snapshot restored successfully

To check that the snapshot was successfully restored, get the name of the new Pod GKE creates for the updated Deployment:

kubectl get pods -l app=hello-app

Verify that the test file exists:

kubectl exec NEW_POD_NAME -- sh -c 'cat /usr/share/hello/hello.txt'

Replace NEW_POD_NAME with the name of the new Pod GKE created.

The output is similar to the following:

Hello World!

Cleaning up

Delete the VolumeSnapshot:
```
kubectl delete volumesnapshot my-snapshot
```
Note: If a volume snapshot's VolumeSnapshotClass has deletionPolicy:Delete, the corresponding VolumeSnapshotContent and the physical snapshot on the storage system are also deleted. If it has a deletionPolicy:Retain, GKE retains the underlying snapshot.

Delete the VolumeSnapshotClass:

kubectl delete volumesnapshotclass my-snapshotclass

Delete the Deployment:
```
kubectl delete deployments hello-app
```
Delete the PersistentVolumeClaim objects:
```
kubectl delete pvc my-pvc pvc-restore
```

What's next

Read the Kubernetes Volume Snapshot documentation.
Learn about volume expansion.
Learn how to manually install a CSI driver.

Using volume snapshots

Requirements

Before you begin

Using gcloud init

Using gcloud config

Creating and using a volume snapshot

Create a PersistentVolumeClaim and a Deployment

Add a test file to the volume

Create a VolumeSnapshotClass object

v1beta1

v1

Create a VolumeSnapshot

v1beta1

v1

Delete the test file

Restore the volume snapshot

Check that the snapshot restored successfully

Cleaning up

What's next

Create a `VolumeSnapshotClass` object