Creating a Pod Mounted with an EVS Volume

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 CCE 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

1. Use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl.
2. 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.

3. Run the following command to create the workload:

   kubectl create -f evs-deployment-example.yaml

Using EVS Volumes for StatefulSets

1. Use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl.
2. 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-west-101
             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.

3. Run the following command to create the workload:

   kubectl create -f evs-statefulset-example.yaml

Verifying Persistent Storage of an EVS Volume

1. 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

2. Run the following command to create a file named test in the /tmp directory:

   kubectl exec evs-statefulset-example-0 -- touch /tmp/test

3. 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

4. Run the following command to delete the pod named evs-statefulset-example-0:

   kubectl delete po evs-statefulset-example-0

5. 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.