Scenario

CCE allows you to use an existing SGS volume to create a StatefulSet (by using a PVC).

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.

Procedure

1. Create an SFS volume by referring to Creating an SFS Volume and record the volume name.
2. Use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl.
3. Create a YAML file for creating the workload. Assume that the file name is sfs-statefulset-example.yaml.

   touch sfs-statefulset-example.yaml

   vi sfs-statefulset-example.yaml

   Configuration example:

   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: sfs-statefulset-example
     namespace: default
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: sfs-statefulset-example
     template:
       metadata:
         labels:
           app: sfs-statefulset-example
       spec:
         volumes: 
         - name: pvc-sfs-example 
           persistentVolumeClaim:
             claimName: pvc-sfs-example     
         containers:
         - name: container-0
           image: 'nginx:latest'
           volumeMounts:
             - name: pvc-sfs-example
               mountPath: /tmp
         restartPolicy: Always
         imagePullSecrets:
         - name: default-secret 
     serviceName: sfs-statefulset-example-headless
     updateStrategy:
       type: RollingUpdate

   Table 1 Key parameters

   Parent Parameter	Parameter	Description
   spec	replicas	Number of pods.
   metadata	name	Name of the new workload.
   spec.template.spec.containers	image	Image used by the workload.
   spec.template.spec.containers.volumeMounts	mountPath	Mount path of a container.
   spec	serviceName	Service corresponding to the workload. For details about how to create a Service, see Creating a StatefulSet.
   spec.template.spec.volumes.persistentVolumeClaim	claimName	Name of an existing PVC.

   Example of mounting an SFS volume to a StatefulSet (PVC template-based, dedicated volume):

   Example YAML file:

   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: sfs-statefulset-example
     namespace: default
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: sfs-statefulset-example
     template:
       metadata:
         labels:
           app: sfs-statefulset-example
       spec:
         containers:
           - name: container-0
             image: 'nginx:latest'
             volumeMounts:
               - name: pvc-sfs-auto-example
                 mountPath: /tmp
         restartPolicy: Always
         imagePullSecrets:
           - name: default-secret
     volumeClaimTemplates:
       - metadata:
           name: pvc-sfs-auto-example
           namespace: default
         spec:
           accessModes:
             - ReadWriteMany
           resources:
             requests:
               storage: 10Gi
           storageClassName: csi-nas
     serviceName: sfs-statefulset-example-headless
     updateStrategy:
       type: RollingUpdate

   

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

4. Create a StatefulSet.

   kubectl create -f sfs-statefulset-example.yaml

Verifying Persistent Storage of an SFS Volume

1. Query the pod and SFS volume of the deployed workload (for example, sfs-statefulset-example).
   1. Run the following command to query the pod name of the workload:

      kubectl get po | grep sfs-statefulset-example

      Expected outputs:

      sfs-statefulset-example-0   1/1     Running   0          2m5s

   2. Run the following command to check whether an SFS volume is mounted to the /tmp directory:

      kubectl exec sfs-statefulset-example-0 -- mount|grep /tmp

      Expected outputs:

      sfs-nas01.cn-north-4.myhuaweicloud.com:/share-c56b9aa4 on /tmp type nfs (rw,relatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,nolock,noresvport,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=10.79.96.32,mountvers=3,mountport=2050,mountproto=tcp,local_lock=all,addr=10.79.96.32)

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

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

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

   kubectl exec sfs-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 sfs-statefulset-example-0:

   kubectl delete po sfs-statefulset-example-0

5. Check whether the data file in the SFS volume 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:

      sfs-statefulset-example-0   1/1     Running   0          2m

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

      kubectl exec sfs-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 SFS volume can be persistently stored.

Related Operations

Creating an SFS Turbo Volume in subpath Mode