vSphere Container Storage Plug-in supports volume topology and availability zones in vSphere environment. You can deploy a Kubernetes workload to a specific region or zone defined in the topology using the default Immediate volume binding mode. The mode indicates that volume binding and dynamic provisioning occur immediately after the PersistentVolumeClaim is created.

To deploy workloads with Immediate binding mode in topology-aware environment, you must specify zone parameters in the StorageClass.

Prerequisites

Enable topology in the native Kubernetes cluster in your vSphere environment. For more information, see Deploy the vSphere Container Storage Plug-in with Topology.

Procedure

  1. Create a StorageClass with Immediate volume binding mode.
    When you do not specify the volume binding mode, it is Immediate by default.
    You can also specify zone parameters. In the following example, the StorageClass can provision volumes on either zone-a or zone-b.
    kind: StorageClass
    apiVersion: storage.k8s.io/v1
    metadata:
      name: example-multi-zones-sc
    provisioner: csi.vsphere.vmware.com
    allowedTopologies:
      - matchLabelExpressions:
          - key: topology.csi.vmware.com/k8s-region
            values:
              - region-1
          - key: topology.csi.vmware.com/k8s-zone
            values:
              - zone-a
              - zone-b
  2. Create a PersistentVolumeClaim to use the StorageClass.
    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      name: example-multi-zones-pvc
    spec:
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 100Mi
      storageClassName: example-multi-zones-sc
  3. Check that the PVC is bound.
    $ kubectl get pvc example-multi-zones-pvc
    NAME                      STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS             AGE
    example-multi-zones-pvc   Bound    pvc-b489e551-9c76-44ca-9434-76c628836748   100Mi      RWO            example-multi-zones-sc   3s
  4. Verify that the PV node affinity rules include at least one domain within zone-a or zone-b depending on whether the selected datastore is local or shared across zones.
    root@k8s-control-108-1632518174:~# kubectl describe pv pvc-b489e551-9c76-44ca-9434-76c628836748
    Name:              pvc-b489e551-9c76-44ca-9434-76c628836748
    Labels:            <none>
    Annotations:       pv.kubernetes.io/provisioned-by: csi.vsphere.vmware.com
    Finalizers:        [kubernetes.io/pv-protection]
    StorageClass:      example-multi-zones-sc
    Status:            Bound
    Claim:             default/example-multi-zones-pvc
    Reclaim Policy:    Delete
    Access Modes:      RWO
    VolumeMode:        Filesystem
    Capacity:          100Mi
    Node Affinity:    
      Required Terms: 
        Term 0:        topology.csi.vmware.com/k8s-zone in [zone-b]
                       topology.csi.vmware.com/k8s-region in [region-1]
    Message:          
    Source:
        Type:              CSI (a Container Storage Interface (CSI) volume source)
        Driver:            csi.vsphere.vmware.com
        FSType:            ext4
        VolumeHandle:      db13a347-0fd5-4b8a-894c-23cf84ab2973
        ReadOnly:          false
        VolumeAttributes:      storage.kubernetes.io/csiProvisionerIdentity=1634758806527-8081-csi.vsphere.vmware.com
                               type=vSphere CNS Block Volume
    Events:                <none>
  5. Create an application to use the PVC.
    apiVersion: v1
    kind: Pod
    metadata:
      name: example-multi-zones-pod
    spec:
      containers:
        - name: test-container
          image: gcr.io/google_containers/busybox:1.24
          command: ["/bin/sh", "-c", "echo 'hello' > /mnt/volume1/index.html  && chmod o+rX /mnt /mnt/volume1/index.html && while true ; do sleep 2 ; done"]
          volumeMounts:
            - name: test-volume
              mountPath: /mnt/volume1
      restartPolicy: Never
      volumes:
        - name: test-volume
          persistentVolumeClaim:
            claimName: example-multi-zones-pvc
    You can notice that the pod is scheduled in to the zone where volume has been provisioned. In this example, it is zone-b.
    $ kubectl get pods -o wide
    NAME                      READY   STATUS    RESTARTS   AGE     IP            NODE         NOMINATED NODE   READINESS GATES
    example-multi-zones-pod   1/1     Running   0          3m53s   10.244.5.34   k8s-node-2   <none>           <none>
     
    $ kubectl get node k8s-node-2 --show-labels
    NAME         STATUS   ROLES    AGE  VERSION   LABELS
    k8s-node-2   Ready    <none>   2d   v1.21.1   topology.csi.vmware.com/k8s-region=region-1,topology.csi.vmware.com/k8s-zone=zone-b

Example: StorageClass with Additional Restrictive Parameters

You can use additional parameters, such as storagepolicyname, in the StorageClass to further restrict the selection of a datastore for volume provisioning. For example, if you have a shared datastore datastore-AB accessible to zone-a and zone-b, create a storage policy that points to the datastore-AB. And then mention this storage policy as a parameter in the storage class.

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: example-multi-zones-sc
provisioner: csi.vsphere.vmware.com
parameters:
  storagepolicyname: "shared datastore zones A and B"
allowedTopologies:
  - matchLabelExpressions:
      - key: topology.csi.vmware.com/k8s-region
        values:
          - region-1
      - key: topology.csi.vmware.com/k8s-zone
        values:
          - zone-a
          - zone-b