Scenario

After an EVS volume is created or imported to CCE, you can mount it to a workload.

EVS disks cannot be attached across AZs. Before mounting a volume, you can run the kubectl get pvc command to query the available PVCs in the AZ where the current cluster is located.

Prerequisites

You have created a cluster and installed the CSI plug-in (everest) in the cluster.

Notes and Constraints

The following configuration example applies to clusters of Kubernetes 1.15 or later.

Using EVS Volumes for Deployments

Use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl.

Run the following commands to configure the evs-deployment-example.yaml file, which is used to create a Deployment.

touch evs-deployment-example.yaml

vi evs-deployment-example.yaml

Example of mounting an EVS volume to a Deployment (PVC-based, shared volume):

apiVersion: apps/v1 
kind: Deployment 
metadata: 
  name: evs-deployment-example 
  namespace: default 
spec: 
  replicas: 1 
  selector: 
    matchLabels: 
      app: evs-deployment-example 
  template: 
    metadata: 
      labels: 
        app: evs-deployment-example 
    spec: 
      containers: 
      - image: nginx
        name: container-0 
        volumeMounts: 
        - mountPath: /tmp 
          name: pvc-evs-example 
      imagePullSecrets:
        - name: default-secret
      restartPolicy: Always 
      volumes: 
      - name: pvc-evs-example 
        persistentVolumeClaim: 
          claimName: pvc-evs-auto-example

**Table 1** Key parameters
Parent Parameter	Parameter	Description
spec.template.spec.containers.volumeMounts	name	Name of the volume mounted to the container.
spec.template.spec.containers.volumeMounts	mountPath	Mount path of the container. In this example, the volume is mounted to the /tmp directory.
spec.template.spec.volumes	name	Name of the volume.
spec.template.spec.volumes.persistentVolumeClaim	claimName	Name of an existing PVC.

spec.template.spec.containers.volumeMounts.name and spec.template.spec.volumes.name must be consistent because they have a mapping relationship.

Run the following command to create the workload:
kubectl create -f evs-deployment-example.yaml

Using EVS Volumes for StatefulSets

Use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl.

Run the following commands to configure the evs-statefulset-example.yaml file, which is used to create a Deployment.

touch evs-statefulset-example.yaml

vi evs-statefulset-example.yaml

Mounting an EVS volume to a StatefulSet (PVC template-based, non-shared volume):

Example YAML:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: evs-statefulset-example
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: evs-statefulset-example
  template:
    metadata:
      labels:
        app: evs-statefulset-example
    spec:
      containers:
        - name: container-0
          image: 'nginx:latest'
          volumeMounts:
            - name: pvc-evs-auto-example
              mountPath: /tmp
      restartPolicy: Always
      imagePullSecrets:
        - name: default-secret
  volumeClaimTemplates:
    - metadata:
        name: pvc-evs-auto-example
        namespace: default
        labels:
          failure-domain.beta.kubernetes.io/region: eu-de
          failure-domain.beta.kubernetes.io/zone: 
        annotations:
          everest.io/disk-volume-type: SAS
      spec:
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
            storage: 10Gi
        storageClassName: csi-disk   
  serviceName: evs-statefulset-example-headless
  updateStrategy:
    type: RollingUpdate

**Table 2** Key parameters
Parent Parameter	Parameter	Description
metadata	name	Name of the created workload.
spec.template.spec.containers	image	Image of the workload.
spec.template.spec.containers.volumeMount	mountPath	Mount path of the container. In this example, the volume is mounted to the /tmp directory.
spec	serviceName	Service corresponding to the workload. For details about how to create a Service, see Creating a StatefulSet.

spec.template.spec.containers.volumeMounts.name and spec.volumeClaimTemplates.metadata.name must be consistent because they have a mapping relationship.

Run the following command to create the workload:
kubectl create -f evs-statefulset-example.yaml

Verifying Persistent Storage of an EVS Volume

Query the pod and EVS files of the deployed workload (for example, evs-statefulset-example).
1. Run the following command to query the pod name of the workload:
```
kubectl get po | grep evs-statefulset-example
```
  Expected outputs:
```
evs-statefulset-example-0   1/1     Running   0          22h
```
2. Run the following command to check whether an EVS volume is mounted to the /tmp directory:
```
kubectl exec evs-statefulset-example-0 -- df tmp
```
  Expected outputs:
```
/dev/sda        10255636 36888  10202364   1% /tmp
```
Run the following command to create a file named test in the /tmp directory:
```
kubectl exec evs-statefulset-example-0 -- touch /tmp/test
```

Run the following command to view the file in the /tmp directory:

kubectl exec evs-statefulset-example-0 -- ls -l /tmp

Expected outputs:

-rw-r--r-- 1 root root     0 Jun  1 02:50 test

Run the following command to delete the pod named evs-statefulset-example-0:
```
kubectl delete po evs-statefulset-example-0
```
Check whether the file still exists after the pod is rebuilt.
1. Run the following command to query the name of the rebuilt pod:
```
kubectl get po
```
  Expected outputs:
```
evs-statefulset-example-0   1/1     Running   0          2m
```
2. Run the following command to view the file in the /tmp directory:
```
kubectl exec evs-statefulset-example-0 -- ls -l /tmp
```
  Expected outputs:
```
-rw-r--r-- 1 root root     0 Jun  1 02:50 test
```
3. The test file still exists after the pod is rebuilt, indicating that the data in the EVS volume can be persistently stored.

Creating a Deployment Mounted with an EVS Volume

Scenario

Prerequisites

Notes and Constraints

Using EVS Volumes for Deployments

Using EVS Volumes for StatefulSets

Verifying Persistent Storage of an EVS Volume