Creating a StatefulSet Mounted with an SFS Turbo Volume

Scenario

CCE allows you to use an existing SFS Turbo volume to create a StatefulSet.

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

Create an SFS Turbo volume and record the volume name.
Use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl.

Create a YAML file for creating the workload. Assume that the file name is sfsturbo-statefulset-example.yaml.

touch sfsturbo-statefulset-example.yaml

vi sfsturbo-statefulset-example.yaml

Configuration example:

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

**Table 1** Key parameters
Parameter	Description
replicas	Number of pods.
name	Name of the new workload.
image	Image used by the workload.
mountPath	Mount path of a container.
serviceName	Service corresponding to the workload. For details about how to create a Service, see Creating a StatefulSet.
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.

Create the StatefulSet.
kubectl create -f sfsturbo-statefulset-example.yaml

Verifying Persistent Storage of an SFS Turbo Volume

Query the pod and SFS Turbo volume of the deployed workload (for example, sfsturbo-statefulset-example).

Run the following command to query the pod name of the workload:

kubectl get po | grep sfsturbo-statefulset-example

Expected outputs:

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

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

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

Expected outputs:

192.168.0.108:/ 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=192.168.0.108,mountvers=3,mountport=20048,mountproto=tcp,local_lock=all,addr=192.168.0.108)

Run the following command to create a file named test in the /tmp directory:
```
kubectl exec sfsturbo-statefulset-example-0 -- touch /tmp/test
```

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

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