Creating a Storage Class in Microsoft Azure

Introduction

Azure volumes can be:

• Azure Disks

• Azure Files

• Azure NetApp Files

• Azure Blobs.

To provide a PersistentVolume, you can use only:

• Azure Disks

• Azure Files

As noted in the Volumes section, the choice of Disks or Files is often determined by the need for concurrent access to the data or the performance tier.

Prerequisites

• Make sure you have an existing AKS Cluster.

• Make sure you're connected to the cluster. Quickstart: Deploy an Azure Kubernetes Service cluster using the Azure CLI

Steps to create Disk and Network Volumes

DISK VOLUMES

The main focus of the next steps is preparing your cluster to support Disk Volumes.

1. Create a file named csi_rwo.yaml.

2. Copy and paste the content below into the csi_rwo.yaml file:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: bns-disk-sc
provisioner: disk.csi.azure.com
parameters:
  skuName: <insert a valid SKU type>
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

The complete list of valid SKU types is available on the Microsoft documentation website.

3. Save the file and exit from edit mode

4. Apply the file to Kubernetes using the following command:

kubectl apply -f csi_rwo.yaml

// OUTPUT
storageclass.storage.k8s.io/bns-disk-sc created

Testing the Storage Class

1. Create a file named claim_rwo.yaml and paste the content below inside it.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: test-claim-volume
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: bns-disk-sc
  resources:
    requests:
      storage: 5Gi

2. Apply the claim:

kubectl apply -f claim_rwo.yaml

3. Now it's time to create a pod that uses the claim. Create a new file named pod.yaml and paste the content below inside it:

kind: Pod
apiVersion: v1
metadata:
  name: nginx
spec:
  containers:
    - name: myfrontend
      image: mcr.microsoft.com/oss/nginx/nginx:1.15.5-alpine
      volumeMounts:
      - mountPath: "/mnt/azure"
        name: test-claim-volume
  volumes:
    - name: test-claim-volume
      persistentVolumeClaim:
        claimName: test-claim-volume

4. Apply the file

kubectl apply -f pod.yaml

5. Make sure everything worked out:

kubectl get pvc

// OUTPUT
NAME                STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
test-claim-volume   Bound    pvc-8ad14dec-2c8b-41b5-aec0-d953f0c03764   5Gi        RWO            bns-disk-sc    3m7s

6. Now let's check if the pod is running:

kubectl get pods

7. Cleanup the resources:

kubectl delete -f claim_rwo.yaml

kubectl delete -f pod.yaml

The volume type disk will be automatically provisioned by Azure using the defined storage class.

NETWORK VOLUMES

The NFS component that has the Volume mounted will be exported using a Kubernetes deployment.

Creating a NFS server

Start by creating a deployment file nfs-deployment.yaml:

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nfs-server-bns-pvc
spec:
  storageClassName: managed-csi
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 100Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
    name: nfs-server-bns
spec:
    replicas: 1
    selector:
        matchLabels:
            io.kompose.service: nfs-server-bns
    template:
        metadata:
            labels:
                io.kompose.service: nfs-server-bns
        spec:
            containers:
                - name: nfs-server-bns
                  image: itsthenetwork/nfs-server-alpine:latest
                  volumeMounts:
                      - name: nfs-storage
                        mountPath: /nfsshare
                  env:
                      - name: SHARED_DIRECTORY
                        value: "/nfsshare"
                  ports:
                      - name: nfs
                        containerPort: 2049   # <- export port
                  securityContext:
                      privileged: true      # <- privileged mode is mandentory.
            volumes:
                - name: nfs-storage
                  persistentVolumeClaim:
                      claimName: nfs-server-bns-pvc

Apply the deployment file:

kubectl apply -f nfs-deployment.yaml

This will create the container which will export a host volume

Creating a Kubernetes service for nfs-deployment.yaml

Create a file named service.yaml containing the text below:

apiVersion: v1
kind: Service
metadata:
    name: srv-nfs-server-bns
    labels:
        io.kompose.service: nfs-server-bns
spec:
    ports:
        -
            name: nfs-server-bns-2049k
            port: 2049
            protocol: TCP
            targetPort: 2049
    selector:
        io.kompose.service: nfs-server-bns

Apply the file

kubectl apply -f service.yaml

Wait for the service and pod to be created. Check status using commands:

kubectl get pods

kubectl get svc

Use Helm charts to create the Storage Class

Retrieve the Service Endpoint IP using the command below:

kubectl get endpoints

// OUTPUT
kubernetes                                                   100.65.7.129:443                                                   34d
srv-nfs-server-bns                                           10.244.0.15:2049                                                   15h

In this case, 10.244.0.15 is the NFS Server IP which will be used in the Helm Chart command.

2049 is the port used for NFS mounts.

Add the following Helm Chart repository:

helm repo add nfs-subdir-external-provisioner https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner/

Use the Helm Chart to create the Storage Class:

helm install nfs-subdir-external-provisioner-vv3 nfs-subdir-external-provisioner/nfs-subdir-external-provisioner \
--set nfs.server=NFS_SERVICE_ENDPOINT_IP --set nfs.path="/" --set storageClass.name=bns-network-sc \
--set "nfs.mountOptions={nfsvers=4.1,proto=tcp}"

• Replace NFS_SERVICE_ENDPOINT_IP with the IP of your NFS service Endpoint. In our case, the IP is 10.244.0.15 (visible in the Output of a previous step).

Verifying the presence of the bns-network-sc storage class

Wait until the Storage Class is created, check status using command:

kubectl get sc

// OUTPUT
NAME                    PROVISIONER                                         RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
bns-network-sc          cluster.local/nfs-subdir-external-provisioner-vv3   Delete          Immediate              true                   39m

Testing the Storage Class

1. Create the test.yaml file with the contents below.

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: test-pvc-network
spec:
  resources:
    requests:
      storage: 5Gi
  accessModes:
    - ReadWriteMany
  storageClassName: bns-network-sc
---
apiVersion: v1
kind: Pod
metadata:
  name: test-app-network
  labels:
    name: test-network
spec:
  containers:
  - name: app
    image: centos
    command: ["/bin/sh"]
    args: ["-c", "while true; do echo $(date -u) >> /data/out; sleep 5; done"]
    volumeMounts:
      - name: persistent-storage-network
        mountPath: /data
    resources:
      limits:
        memory: "50Mi"
        cpu: "50m"
  volumes:
    - name: persistent-storage-network
      persistentVolumeClaim:
        claimName: test-pvc-network

2. Apply test.yaml:

kubectl apply -f test.yaml

// OUTPUT
persistentvolumeclaim/test-pvc-network created
pod/test-app-network created

3. Let's make sure that test-pvc-network has the status Bound by performing the next command:

kubectl get pvc

// OUTPUT
NAME                                      STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS     AGE
jenkins-backup                            Bound    pvc-1ead6f96-be65-46b6-81b9-1bb0ab69f773   5Gi        RWO            default          14d
pvc-nfs-subdir-external-provisioner-vv3   Bound    pv-nfs-subdir-external-provisioner-vv3     10Mi       RWO                             93s
test-pvc-network                          Bound    pvc-60600a30-74a5-4035-9052-d4a35c1617b5   5Gi        RWX            bns-network-sc   25s

4. Check that the pod reached the Running status by performing the following command:

kubectl get pods

// OUTPUT
NAME                                                   READY   STATUS    RESTARTS   AGE
nfs-server-bns-5876f5997-9gv5j                         1/1     Running   0          3m42s
nfs-subdir-external-provisioner-vv3-65b74898c9-g87rp   1/1     Running   0          98s
test-app-network                                       1/1     Running   0          30s

5. Verify that the test-app-network pod is writing data to the volume:

kubectl exec test-app-network -- bash -c "cat data/out"

// OUTPUT
Tue Jul 26 12:24:22 UTC 2022
Tue Jul 26 12:24:28 UTC 2022
Tue Jul 26 12:24:33 UTC 2022
Tue Jul 26 12:24:38 UTC 2022
Tue Jul 26 12:24:43 UTC 2022
Tue Jul 26 12:24:48 UTC 2022
Tue Jul 26 12:24:53 UTC 2022
Tue Jul 26 12:24:58 UTC 2022
Tue Jul 26 12:25:03 UTC 2022
Tue Jul 26 12:25:08 UTC 2022
Tue Jul 26 12:25:13 UTC 2022

6. If your results are similar with the Output displayed above, then you've completed the process successfully and you can delete the test resources.

• Delete the PVC and the Pod. This will also cause the PV to be deleted:

kubectl delete -f test.yaml

// OUTPUT
persistentvolumeclaim "test-pvc-network" deleted
pod "test-app-network" deleted