Using the Compute Engine persistent disk CSI Driver

Google Kubernetes Engine (GKE) provides a simple way for you to automatically deploy and manage the Compute Engine persistent disk Container Storage Interface (CSI) Driver in your clusters.

The Compute Engine persistent disk CSI Driver version is tied to GKE version numbers. The Compute Engine persistent disk CSI Driver version is typically the latest driver available at the time that the GKE version is released. The drivers update automatically when the cluster is upgraded to the latest GKE patch.

Note: Because the Compute Engine persistent disk CSI Driver and some of the other associated CSI components are deployed as separate containers, they incur resource usage (VM CPU, memory, and boot disk) on Kubernetes nodes. VM CPU usage is typically tens of millicores and memory usage is typically tens of MB. Boot disk usage is mostly incurred by the logs of the CSI driver and other system containers in the Deployment.

Benefits of using the Compute Engine persistent disk CSI Driver

Using the Compute Engine persistent disk CSI Driver instead of the Kubernetes in-tree gcePersistentDisk volume plugin provides the following benefits:

• CSI drivers are the future of storage extension in Kubernetes. Kubernetes has announced that the in-tree volume plugins are expected to be removed from Kubernetes in version 1.21. For details, see Kubernetes In-Tree to CSI Volume Migration Moves to Beta. After in-tree volume plugins are removed, existing volumes using in-tree volume plugins will communicate through CSI drivers instead.
• It enables the automatic deployment and management of the persistent disk driver without having to manually set it up, or use the in-tree volume plugin.
• It provides additional persistent disk features in GKE. For example:
  • You can use customer-managed encryption keys (CMEKs) with the Compute Engine persistent disk CSI Driver, but not the in-tree volume plugin. These keys are used to encrypt the data encryption keys that encrypt your data. To learn more about CMEK on GKE, see Using CMEK.
  • You can use volume snapshots with the Compute Engine persistent disk CSI Driver. 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.
• Bug fixes and feature updates are rolled out independently from minor Kubernetes releases. This release schedule typically results in a faster release cadence.

Requirements

To use the Compute Engine persistent disk CSI Driver, you must use GKE versions that are 1.14 or later.

Enabling the Compute Engine persistent disk CSI Driver on a new cluster

Newly created clusters using version 1.18.10-gke.2100 or later, or 1.19.3- gke.2100 or later have the Compute Engine persistent disk CSI Driver enabled by default. If you created a cluster with one of these versions, you do not need to take any of the steps in this section.

If you want to create a cluster with a version where the Compute Engine persistent disk CSI Driver is not automatically enabled, you can use the gcloud command-line tool or the Google Cloud Console.

To enable the driver on cluster creation, complete the following steps:

gcloud

gcloud container clusters create CLUSTER-NAME \
    --addons=GcePersistentDiskCsiDriver \
    --cluster-version=VERSION

Replace the following:

• CLUSTER-NAME: the name of your cluster.
• VERSION: the GKE version number. You must select a version of 1.14 or higher to use this feature.

For the full list of flags, see the gcloud container clusters create documentation.

Console

1. Visit the Google Kubernetes Engine menu in Cloud Console.

   Visit the Google Kubernetes Engine menu

2. Click Create.

3. Configure your cluster as you want. For details on the types of clusters that you can create, see Types of clusters.

4. From the navigation pane, under Cluster, click Features.

5. Select the Enable Compute Engine persistent disk CSI Driver checkbox.

6. Click Create.

After you have enabled the Compute Engine persistent disk CSI Driver, you can use the driver in Kubernetes volumes using the driver and provisioner name: pd.csi.storage.gke.io.

Enabling the Compute Engine persistent disk CSI Driver on an existing cluster

To enable the Compute Engine persistent disk CSI Driver in existing clusters, use the gcloud command-line tool or the Google Cloud Console.

To enable the driver on an existing cluster, complete the following steps:

gcloud

gcloud container clusters update CLUSTER-NAME \
   --update-addons=GcePersistentDiskCsiDriver=ENABLED

Replace CLUSTER-NAME with the name of the existing cluster.

Console

1. In the Cloud Console, go to the Google Kubernetes Engine menu.

   Go to the Google Kubernetes Engine menu

2. Click the cluster's Edit button, which looks like a pencil.

3. Expand Add-ons.

4. From the Compute Engine persistent disk CSI Driver dropdown, select Enabled.

5. Click Save.

Disabling the Compute Engine persistent disk CSI Driver

Disable the Compute Engine persistent disk CSI Driver using gcloud command-line tool or the Google Cloud Console.

Note: If you disable the driver, then any Pods currently using PersistentVolumes owned by the driver do not terminate. Any new Pods that try to use those PersistentVolumes also fail to start.

To disable the driver on an existing cluster, complete the following steps:

gcloud

gcloud container clusters update CLUSTER-NAME \
    --update-addons=GcePersistentDiskCsiDriver=DISABLED

Replace CLUSTER-NAME with the name of the existing cluster.

Console

1. In the Cloud Console, go to the Google Kubernetes Engine menu.

   Go to Google Kubernetes Engine

2. Click the cluster's Edit button, which looks like a pencil.

3. Expand Add-ons.

4. From the Compute Engine persistent disk CSI Driver dropdown, select Disabled.

5. Click Save.

Using the Compute Engine persistent disk CSI Driver

The following sections describe the typical process for using a Kubernetes volume backed by a CSI driver in GKE.

Create a StorageClass

After you enable the Compute Engine persistent disk CSI Driver, GKE automatically installs a StorageClass for it. The StorageClass name is standard-rwo. Some older cluster versions, however, might have one of the following names:

• singlewriter-standard
• standard-singlewriter

You can find the name of your installed StorageClass by running the following command:

kubectl get sc

You can also install a different StorageClass that uses the Compute Engine persistent disk CSI Driver by adding pd.csi.storage.gke.io in the provisioner field.

For example, you could create a StorageClass using the following file named pd-example-class.yaml:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: pd-example
provisioner: pd.csi.storage.gke.io
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true
parameters:
  type: pd-balanced

Any persistent disk type can be specified in the type parameter (for example pd-ssd, pd-standard or pd-balanced).

After creating the pd-example-class.yaml file, run the following command:

kubectl create -f pd-example-class.yaml

Create a PersistentVolumeClaim

You can create a PersistentVolumeClaim that references the Compute Engine persistent disk CSI Driver's StorageClass.

The following file, named pvc-example.yaml, uses the pre-installed storage class standard-rwo:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: podpvc
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: standard-rwo
  resources:
    requests:
      storage: 6Gi

After creating the PersistentVolumeClaim manifest, run the following command:

kubectl create -f pvc-example.yaml

In the pre-installed StorageClass (standard-rwo), volumeBindingMode is set to WaitForFirstConsumer. When volumeBindingMode is set to WaitForFirstConsumer, the PersistentVolume is not provisioned until a Pod referencing the PersistentVolumeClaim is scheduled. If volumeBindingMode in the StorageClass is set to Immediate (or it's omitted), a persistent-disk-backed PersistentVolume is provisioned after the PersistentVolumeClaim is created.

Create a Pod that consumes the volume

When using Pods with PersistentVolumes, we recommend that you use a workload controller (such as a Deployment or StatefulSet). While you would not typically use a standalone Pod, the following example uses one for simplicity.

The following example consumes the volume that you created in the previous section:

apiVersion: v1
kind: Pod
metadata:
  name: web-server
spec:
  containers:
   - name: web-server
     image: nginx
     volumeMounts:
       - mountPath: /var/lib/www/html
         name: mypvc
  volumes:
   - name: mypvc
     persistentVolumeClaim:
       claimName: podpvc
       readOnly: false

Known issues

Due to a 128 character restriction in the CSI Node ID Spec and how GKE generates instance names, installing the Compute Engine persistent disk CSI Driver might fail on new and existing GKE clusters for certain node pools. For more information, see this GitHub issue.

This issue is fixed in the following versions:

• 1.16.15-gke.1700 and later
• 1.17.9-6300 and later
• 1.18.6-4801 and later

If you are using a cluster with an earlier version, upgrade to one of the listed versions to resolve the issue.

What's next

• Learn how to use volume expansion.
• Learn how to use volume snapshots.
• Read more about the driver on GitHub.