Static cloud disk volume for persistent storage - Flexvolume

Limitations

• A cloud disk can be mounted to only one pod at a time.

• A cloud disk can be mounted only to a node in the same zone.

Create a PV

1. Create a file named pv-static.yaml.

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: <your-disk-id>
     labels:
       alicloud-pvname: <your-disk-id>
       failure-domain.beta.kubernetes.io/zone: <your-zone>
       failure-domain.beta.kubernetes.io/region: <your-region>
   spec:
     capacity:
       storage: 20Gi
     accessModes:
       - ReadWriteOnce
     flexVolume:
       driver: "alicloud/disk"
       fsType: "ext4"
       options:
         volumeId: "<your-disk-id>"

   Note

   • alicloud-pvname: <your-disk-id>: The PV name. Must match your cloud disk ID.

   • failure-domain.beta.kubernetes.io/zone: <your-zone>: The cloud disk zone, for example, cn-hangzhou-b.

   • failure-domain.beta.kubernetes.io/region: <your-region>: The cloud disk region, for example, cn-hangzhou.

   For multi-zone clusters, specify failure-domain.beta.kubernetes.io/zone and failure-domain.beta.kubernetes.io/region to ensure pods are scheduled in the same zone as the cloud disk.

2. Create the PV.

   kubectl create -f pv-static.yaml

   Verification Result

   1. Log on to the Container Service Management Console.

   2. In the left-side navigation pane, click Clusters.

   3. On the Clusters page, click the target cluster, or click Details in the Actions column.

   4. In the left-side navigation pane of the cluster management page, choose Volumes > Persistent Volumes. The PV appears with capacity 20Gi, access mode ReadWriteOnce, reclaim policy Retain, and status Available.

Create a PVC

1. Create a file named pvc-static.yaml.

   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: pvc-disk
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 20Gi
     selector:
       matchLabels:
         alicloud-pvname: <your-disk-id>

2. Create the PVC.

   kubectl create -f pvc-static.yaml

   Verification Result

   1. Log on to the Container Service Management Console.

   2. In the left-side navigation pane, click Clusters.

   3. On the Clusters page, click the target cluster, or click Details in the Actions column.

   4. In the left-side navigation pane of the cluster management page, choose Volumes > Persistent Volume Claims.

   5. The PVC appears on the Persistent Volume Claims page.

Create an application

1. Create a file named static.yaml.

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx-static
     labels:
       app: nginx
   spec:
     selector:
       matchLabels:
         app: nginx
     template:
       metadata:
         labels:
           app: nginx
       spec:
         containers:
         - name: nginx
           image: nginx
           volumeMounts:
             - name: disk-pvc
               mountPath: "/data"
         volumes:
           - name: disk-pvc
             persistentVolumeClaim:
               claimName: pvc-disk

2. Create the application.

   kubectl create -f static.yaml

   Verification Result

   1. Log on to the Container Service Management Console.

   2. In the left-side navigation pane, click Clusters.

   3. On the Clusters page, click the target cluster, or click Details in the Actions column.

   4. In the left-side navigation pane of the cluster management page, choose Workloads > Deployments.

   5. The application appears on the Deployments page.

Verify data persistence

1. Get the pod name.

   kubectl get pod | grep static

   Expected output:

   nginx-static-78c7dcb9d7-g****   2/2     Running     0          32s

2. Verify that the cloud disk is mounted to /data.

   kubectl exec nginx-static-78c7dcb9d7-g**** -- df | grep data

   Expected output:

   /dev/vdf        20511312    45080  20449848   1% /data

3. List the files in /data.

   kubectl exec nginx-static-78c7dcb9d7-g**** -- ls /data

   Expected output:

   lost+found

4. Create a file named static in /data.

   kubectl exec nginx-static-78c7dcb9d7-g**** -- touch /data/static

5. List the files in /data.

   kubectl exec nginx-static-78c7dcb9d7-g**** -- ls /data

   Expected output:

   static
   lost+found

6. Delete the pod nginx-static-78c7dcb9d7-g****.

   kubectl delete pod nginx-static-78c7dcb9d7-g****

   Expected output:

   pod "nginx-static-78c7dcb9d7-g****" deleted

7. In a separate terminal, watch Kubernetes delete and recreate the pod.

   kubectl get pod -w -l app=nginx

   Expected output:

   NAME                            READY   STATUS            RESTARTS   AGE
   nginx-static-78c7dcb9d7-g****   2/2     Running           0          50s
   nginx-static-78c7dcb9d7-g****   2/2     Terminating       0          72s
   nginx-static-78c7dcb9d7-h****   0/2     Pending           0          0s
   nginx-static-78c7dcb9d7-h****   0/2     Pending           0          0s
   nginx-static-78c7dcb9d7-h****   0/2     Init:0/1          0          0s
   nginx-static-78c7dcb9d7-g****   0/2     Terminating       0          73s
   nginx-static-78c7dcb9d7-h****   0/2     Init:0/1          0          5s
   nginx-static-78c7dcb9d7-g****   0/2     Terminating       0          78s
   nginx-static-78c7dcb9d7-g****   0/2     Terminating       0          78s
   nginx-static-78c7dcb9d7-h****   0/2     PodInitializing   0          6s
   nginx-static-78c7dcb9d7-h****   2/2     Running           0          8s

8. Get the name of the recreated pod.

   kubectl get pod

   Expected output:

   NAME                            READY   STATUS      RESTARTS   AGE
   nginx-static-78c7dcb9d7-h****   2/2     Running     0          14s

9. List the files in /data. The static file still exists, confirming that data on the cloud disk persists across pod restarts.

   kubectl exec nginx-static-78c7dcb9d7-h**** -- ls /data

   Expected output:

   static
   lost+found