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Multiple Pods Read Write Many

This example shows how to create a static provisioned Amazon EFS persistent volume (PV) and access it from multiple pods with the ReadWriteMany (RWX) access mode. This mode allows the PV to be read and written from multiple pods.

  1. Clone the Amazon EFS Container Storage Interface (CSI) driver GitHub repository to your local system.

    git clone https://github.com/kubernetes-sigs/aws-efs-csi-driver.git

  2. Navigate to the multiple_pods example directory.

    cd aws-efs-csi-driver/examples/kubernetes/multiple_pods/

  3. Retrieve your Amazon EFS file system ID. You can find this in the Amazon EFS console, or use the following AWS CLI command.

    aws efs describe-file-systems --query "FileSystems[*].FileSystemId" --output text

    The example output is as follows.

    fs-582a03f3

  4. Edit the specs/pv.yaml file and replace the volumeHandle value with your Amazon EFS file system ID.

    apiVersion: v1
kind: PersistentVolume
metadata:
  name: efs-pv
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  storageClassName: efs-sc
  csi:
    driver: efs.csi.aws.com
    volumeHandle: fs-582a03f3

Note
spec.capacity is ignored by the Amazon EFS CSI driver because Amazon EFS is an elastic file system. The actual storage capacity value in persistent volumes and persistent volume claims isn't used when creating the file system. However, because storage capacity is a required field in Kubernetes, you must specify a valid value, such as, 5Gi in this example. This value doesn't limit the size of your Amazon EFS file system.

  1. Deploy the efs-sc storage class, the efs-claim PVC, and the efs-pv PV from the specs directory.

    kubectl apply -f specs/pv.yaml
kubectl apply -f specs/claim.yaml
kubectl apply -f specs/storageclass.yaml

  2. List the persistent volumes in the default namespace. Look for a persistent volume with the default/efs-claim claim.

    kubectl get pv -w

    The example output is as follows.

    NAME     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM               STORAGECLASS   REASON   AGE
efs-pv   5Gi        RWX            Retain           Bound    default/efs-claim   efs-sc                  2m50s

    Don't proceed to the next step until the STATUS is Bound.

  3. Deploy the app1 and app2 sample applications from the specs directory. Both pod1 and pod2 consume the PV and write to the same Amazon EFS filesystem at the same time.

    kubectl apply -f specs/pod1.yaml
kubectl apply -f specs/pod2.yaml

  4. Watch the Pods in the default namespace and wait for the app1 and app2 Pods' STATUS to become Running.

    kubectl get pods --watch

Note
It may take a few minutes for the Pods to reach the Running status.

  1. Describe the persistent volume.

    kubectl describe pv efs-pv

    The example output is as follows.

    Name:            efs-pv
Labels:          none
Annotations:     kubectl.kubernetes.io/last-applied-configuration:
                   {"apiVersion":"v1","kind":"PersistentVolume","metadata":{"annotations":{},"name":"efs-pv"},"spec":{"accessModes":["ReadWriteMany"],"capaci...
                 pv.kubernetes.io/bound-by-controller: yes
Finalizers:      [kubernetes.io/pv-protection]
StorageClass:    efs-sc
Status:          Bound
Claim:           default/efs-claim
Reclaim Policy:  Retain
Access Modes:    RWX
VolumeMode:      Filesystem
Capacity:        5Gi
Node Affinity:   none
Message:
Source:
    Type:              CSI (a Container Storage Interface (CSI) volume source)
    Driver:            efs.csi.aws.com
    VolumeHandle:      fs-582a03f3
    ReadOnly:          false
    VolumeAttributes:  none
Events:                none

    The Amazon EFS file system ID is listed as the VolumeHandle.

  2. Verify that the app1 Pod is successfully writing data to the volume.

    kubectl exec -ti app1 -- tail -f /data/out1.txt

    The example output is as follows.

    [...]
Mon Mar 22 18:18:22 UTC 2021
Mon Mar 22 18:18:27 UTC 2021
Mon Mar 22 18:18:32 UTC 2021
Mon Mar 22 18:18:37 UTC 2021
[...]

  3. Verify that the app2 Pod shows the same data in the volume that app1 wrote to the volume.

    kubectl exec -ti app2 -- tail -f /data/out2.txt

    The example output is as follows.

    [...]
Mon Mar 22 18:18:22 UTC 2021
Mon Mar 22 18:18:27 UTC 2021
Mon Mar 22 18:18:32 UTC 2021
Mon Mar 22 18:18:37 UTC 2021
[...]

  4. When you finish experimenting, delete the resources for this sample application to clean up.

    kubectl delete -f specs/

    You can also manually delete the file system and security group that you created.