As part of a StatefulSet, volumeClaimTemplates can provide persistent storage using PersistentVolumes provisioned by a PersistentVolume provisioner of your choice. In this recipe, we will use the Azure storage class to dynamically create PVs for your application:

1. Add the azure-zrs storage class line under the volumeClaimTemplates section of your application deployment manifest, similar to the following example:  

...
  volumeClaimTemplates:
  - metadata:
      name: datadir
      annotations:
        volume.beta.kubernetes.io/storage-class: azure-zrs
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 1G
...

2. In this recipe, we will deploy Redis Statefulset using the azure-zrs storage class. Review the YAML manifest under the src/chapter5/azure directory in the example repository before we execute it:

$ cat azure/redis-statefulset.yml

3. Create the Redis StatefulSet:

$ kubectl apply -f redis-statefulset.yml

4. Verify that pods have been created. In this recipe, our example has StatefulSet with three replicas. As a result, you should see three replicas running, similar to the following output:

$ kubectl get pods
NAME READY STATUS  RESTARTS AGE
rd-0 1/1   Running 0        6m24s
rd-1 1/1   Running 0        4m14s
rd-2 1/1   Running 0        2m13s

5. List the PVCs and PVs created. You should expect to see three PVCs and three PVs created, similar to our example output here:

$ kubectl get pvc, pv
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
datadir-rd-0 Bound pvc-afaafb97-d376-11e9-88a2-a2c82783dcda 1Gi RWO azure-zrs 4m31s
datadir-rd-1 Bound pvc-fc9f3a35-d376-11e9-88a2-a2c82783dcda 1Gi RWO azure-zrs 2m22s
datadir-rd-2 Bound pvc-453d185d-d377-11e9-88a2-a2c82783dcda 1Gi RWO azure-zrs 20s
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-453d185d-d377-11e9-88a2-a2c82783dcda 1Gi RWO Delete Bound default/datadir-rd-2 azure-zrs 22s
pvc-afaafb97-d376-11e9-88a2-a2c82783dcda 1Gi RWO Delete Bound default/datadir-rd-0 azure-zrs 4m42s
pvc-fc9f3a35-d376-11e9-88a2-a2c82783dcda 1Gi RWO Delete Bound default/datadir-rd-1 azure-zrs 2m38s

Now you know how to dynamically create persistent volumes as part of your application deployment on AKS clusters.