Use StorageClasses with your workloads

GKE on AWS automatically deploys the Container Storage Interface (CSI) Driver for Amazon Elastic Block Store (EBS) to provision and manage Amazon EBS volumes in your clusters.

The GKE on AWS EBS CSI Driver version is tied to a GKE on AWS Kubernetes version. The driver version is typically the latest available when the GKE version is released. When the cluster is upgraded, the drivers update automatically.

How to use the default StorageClass

Creating a PersistentVolumeClaim without the field spec.storageClassName set provisions a gp2 volume using the default GKE on AWS EBS CSI Driver StorageClass.

The following YAML creates a PersistentVolumeClaim (PVC) named mypvc with a size of 30 gibibytes.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mypvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 30Gi

How to use a different preinstalled StorageClass

The GKE on AWS EBS CSI Driver also includes the premium-rwo StorageClass, which provisions higher-throughput io1 volumes.

You can use it by specifying it in the spec.storageclassName of the PVC.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mypvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 30Gi
  storageclassName: premium-rwo

How to use a custom StorageClass

You can create additional StorageClasses for EBS volumes or use Container Storage Interface (CSI) Drivers.

  1. Choose if you are using an EBS volume or a specific CSI driver.

    EBS Volume

    You can create your own custom StorageClass that specifies an EBS volume type, file system type, and other parameters. You can find additional StorageClass parameters on the GKE on AWS EBS CSI Driver GitHub page.

    To configure a custom StorageClass, copy the following YAML manifest into a file named my-custom-class.yaml.

    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: CLASS_NAME
provisioner: ebs.csi.aws.com
volumeBindingMode: WaitForFirstConsumer

    Replace CLASS_NAME with the name of your new StorageClass.

    For example, the following YAML creates a new StorageClass that provisions Throughput Optimized HDD EBS volumes formatted with the XFS file system.

    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-custom-class
provisioner: ebs.csi.aws.com
volumeBindingMode: WaitForFirstConsumer
parameters:
  csi.storage.k8s.io/fsType: xfs
  type: st1

    CSI Driver

    You can specify a different CSI driver in the provisioner field.

    To create a StorageClass with another CSI driver, you can use the example YAML below.

    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: CLASS_NAME
provisioner: CSI_DRIVER_NAME
volumeBindingMode: WaitForFirstConsumer
parameters:
  ...

    Replace the following:

    • CSI_DRIVER_NAME with the name of the CSI driver—for example,csi.example.com
    • CLASS_NAME with the name of the StorageClass—for example, my-custom-class

    Configure the sub-fields under parameters according to your CSI driver.

  2. Apply the YAML to your cluster.

    kubectl apply -f my-custom-class.yaml

How to create a PersistentVolumeClaim with a custom StorageClass

  1. Once a custom StorageClass is created, you can specify it in a PVC. The example below creates a PVC named my-pvc that references the StorageClass my-custom-class.

    apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 30Gi
  storageclassName: my-custom-class

How to set the default StorageClass

GKE on AWS uses a default StorageClass called standard-rwo that provisions gp2 EBS volumes. You can change the default to another StorageClass.

To change the default StorageClass:

  1. Update the is-default-class annotation for the standard-rwo StorageClass with kubectl patch.

    kubectl patch storageclass standard-rwo -p \
'{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"false"}}}'

  2. Create a new StorageClass that has the annotation storageclass.kubernetes.io/is-default-class: true.

    The following example StorageClass uses the ebs.csi.aws.com driver. To install another storage driver, see Installing a CSI driver.

    Copy the following YAML into a file named my-custom-class.yaml.

    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: CLASS_NAME
  annotations:
    storageclass.kubernetes.io/is-default-class: true
provisioner: ebs.csi.aws.com
volumeBindingMode: WaitForFirstConsumer
parameters:
  type: EBS_VOLUME_TYPE

    Replace the following:

    • EBS_VOLUME_TYPE: the AWS EBS volume type that the StorageClass creates.
    • CLASS_NAME with the name of your new StorageClass

    For example, the following YAML creates a new default StorageClass that provisions Throughput Optimized HDD EBS volumes formatted with the XFS file system.

    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-custom-default-class
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: ebs.csi.aws.com
volumeBindingMode: WaitForFirstConsumer
parameters:
  csi.storage.k8s.io/fsType: xfs
  type: st1

  3. Apply the new custom class to your cluster.

    kubectl apply -f my-custom-class.yaml

After applying this manifest, GKE on AWS uses the my-custom-default-class StorageClass for new storage requests.

Reference the StorageClass in a StatefulSet

To use your new StorageClass, you must reference it in a StatefulSet's volumeClaimTemplates.

When you reference a StorageClass in a StatefulSet's volumeClaimTemplates specification, Kubernetes provides stable storage using PersistentVolumes (PVs). Kubernetes calls the provisioner defined in the StorageClass to create a new storage volume. After the volume is provisioned, Kubernetes automatically creates a PV.

The following StatefulSet references the my-custom-class StorageClass and provisions a 1 gibibyte volume:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: registry.k8s.io/nginx-slim:0.8
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates: # This is the specification in which you reference the StorageClass
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 1Gi
      storageClassName: my-custom-class # This field references the existing StorageClass

What's next