The product described by this documentation, Anthos Clusters on AWS (previous generation), is now in maintenance mode. All new installs must use the current generation product, Anthos clusters on AWS.

Using EFS file systems

GKE on AWS versions 1.6 and later support the AWS Elastic File System (EFS) through the EFS CSI Driver. This topic explains how to mount an existing EFS file system as a PersistentVolume on your user clusters.

Before you begin

To perform the steps in this topic, you need the following:

An existing EFS file system in the same AWS VPC as your GKE on AWS installation.
At least one EFS mount target in the same AWS VPC as your GKE on AWS installation.
All of your EFS mount targets must belong to the following:
- The private subnets for your GKE on AWS installation. By default, GKE on AWS creates subnets named gke-CLUSTER_ID-private-AWS_ZONE, where CLUSTER_ID is your user cluster ID and AWS_ZONE is the AWS availability zone.
- The node pool security group. By default, GKE on AWS creates node pools named gke-CLUSTER_ID-nodepool, where CLUSTER_ID is your user cluster ID.
From your anthos-aws directory, use anthos-gke to switch context to your user cluster.
```
cd anthos-aws
env HTTPS_PROXY=http://localhost:8118 \
  anthos-gke aws clusters get-credentials CLUSTER_NAME
```
Replace CLUSTER_NAME with your user cluster name.

Using an EFS PersistentVolume

To use an EFS file system as a PersistentVolume with your user clusters, you first create a PersistentVolume and then create a PersistentVolumeClaim which you reference in your workload.

Creating a PersistentVolume

To create a PersistentVolume with the EFS CSI driver, perform the following steps.

From your anthos-aws directory, use anthos-gke to switch context to your user cluster.
```
cd anthos-aws
env HTTPS_PROXY=http://localhost:8118 \
  anthos-gke aws clusters get-credentials CLUSTER_NAME
```
Replace CLUSTER_NAME with your user cluster name.

The PersistentVolume configuration you use depends on if you are connecting directly to the Elastic File System or via an access point. Select if you are connecting to the Elastic File System directly or via an access point.

Connect directly

Copy the following YAML manifest into a file named efs-volume.yaml. The manifest references the EFS storage class you created previously.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: VOLUME_NAME
spec:
  capacity:
    # Note: storage capacity is not used by the EFS CSI driver.
    # It is required by the PersistentVolume spec.
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  storageClassName: "" # storageClassName is not required, see note in the following section.
  claimRef:
    name: CLAIM_NAME
    namespace: default
  csi:
    driver: efs.csi.aws.com
    volumeHandle: EFS_FILE_SYSTEM_ID

Replace the following:

VOLUME_NAME with a name for the persistent volume.
CLAIM_NAME with the name you want to use for the PersistentVolumeClaim.
EFS_FILE_SYSTEM_ID with your EFS file system ID. For example, fs-12345678a.

Access point

Copy the following YAML manifest into a file named efs-volume.yaml. The manifest references the EFS storage class you created previously.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: VOLUME_NAME
spec:
  capacity:
    # Note: storage capacity is not used by the EFS CSI driver.
    # It is required by the PersistentVolume spec.
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  storageClassName: "" # storageClassName is not required, see note in the following section.
  claimRef:
    name: CLAIM_NAME
    namespace: default
  csi:
    driver: efs.csi.aws.com
    volumeHandle: EFS_FILE_SYSTEM_ID::ACCESS_POINT_ID

Replace the following:

VOLUME_NAME with a name for the persistent volume.
CLAIM_NAME with the name you want to use for the PersistentVolumeClaim.
EFS_FILE_SYSTEM_ID with your EFS file system ID. For example, fs-12345678a.
ACCESS_POINT_ID with your access point's ID. For example, fsap-1234567890abcde.

Apply the YAML to your user cluster.

env HTTPS_PROXY=http://localhost:8118 \
  kubectl apply -f efs-volume.yaml

The output confirms the PersistentVolume's creation.

persistentvolume/VOLUME_NAME created

Creating a PersistentVolumeClaim

To use your EFS file system with your workloads, you create a PersistentVolumeClaim.

To create the PersistentVolumeClaim, copy the following YAML manifest into a file named efs-claim.yaml.
```
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: CLAIM_NAME
spec:
  accessModes:
    - ReadWriteMany
  storageClassName: ""
  resources:
    requests:
      storage: 5Gi
```
Replace CLAIM_NAME with a name for your PersistentVolumeClaim. For example, efs-claim1.

Note: You must use the same storageClassName value for your PersistentVolume and PersistentVolumeClaim resources.

Apply the YAML to your user cluster.

env HTTPS_PROXY=http://localhost:8118 \
  kubectl apply -f efs-claim.yaml

The output confirms the PersistentVolumeClaim's creation.

persistentvolumeclaim/CLAIM_NAME created

Create a StatefulSet

After you have created a PersistentVolumeClaim, you can use it in a workload. The steps in this section create an example StatefulSet with your EFS file system mounted. You can also use a PersistentVolumeClaim with other workload types such as Pods and Deployments by referencing the claim in spec.volumes.

To create a StatefulSet that mounts the EFS file system referenced in your PersistentVolumeClaim, perform the following steps.

Copy the following YAML manifest into a file named efs-statefulset.yaml. This example manifest launches an Ubuntu Linux container that mounts your EFS file system at /efs-data. The container writes every five seconds to a file on your EFS file system named out.txt.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: efs-shell
spec:
  selector:
    matchLabels:
      app: test-efs
  serviceName: efs-app
  replicas: 1
  template:
    metadata:
      labels:
        app: test-efs
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: linux
        image: ubuntu:bionic
        command: ["/bin/sh"]
        args: ["-c", "while true; do echo $(date -u) >> /efs-data/out.txt; sleep 5; done"]
        volumeMounts:
        - name: efs-volume
          mountPath: /efs-data
      volumes:
      - name: efs-volume
        persistentVolumeClaim:
          claimName: CLAIM_NAME

Replace the following:

CLAIM_NAME with the name of the PersistentVolumeClaim you specified previously. For example, efs-claim1.

Apply the YAML to your user cluster.
```
env HTTPS_PROXY=http://localhost:8118 \
 kubectl apply -f efs-statefulset.yaml
```
The output confirms the StatefulSet's creation.
```
statefulset.apps/efs-shell created
```
The StatefulSet might take several minutes to download the container image and launch.
Confirm the StatefulSet's Pod is in Running status with kubectl get pods.
```
env HTTPS_PROXY=http://localhost:8118 \
  kubectl get pods -l app=test-efs
```
The output includes the name of the Pod and its status. In the following response, the Pod's name is efs-shell-0.
```
NAME          READY   STATUS    RESTARTS   AGE
efs-shell-0   1/1     Running   0          1m
```
After the Pod is in Running status, use kubectl exec to connect to the Pod hosting the StatefulSet.
```
env HTTPS_PROXY=http://localhost:8118 \
  kubectl exec -it efs-shell-0 -- bash
```
The kubectl command launches a shell on the Pod.
To confirm that your EFS file system is mounted, check the contents of the out.txt file with the tail command.
```
tail /efs-data/out.txt
```
The output contains recent times in UTC.
Disconnect from the Pod with the exit command.
```
exit
```
Your shell returns to your local machine.

To remove the StatefulSet, use kubectl delete.

env HTTPS_PROXY=http://localhost:8118 \
  kubectl delete -f efs-statefulset.yaml

Cleaning up

To remove the resources you created in the previous sections, run the following commands:

env HTTPS_PROXY=http://localhost:8118 \
  kubectl delete -f efs-statefulset.yaml
env HTTPS_PROXY=http://localhost:8118 \
  kubectl delete -f efs-claim.yaml
env HTTPS_PROXY=http://localhost:8118 \
  kubectl delete -f efs-volume.yaml

What's next

Learn about additional ways to use EFS volumes in the aws-efs-csi-driver examples.