Creating a StatefulSet Mounted with an OBS Volume
Scenario
CCE allows you to use an existing OBS volume to create a StatefulSet through 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
- Create an OBS volume by referring to PersistentVolumeClaims (PVCs) and obtain the PVC 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 obs-statefulset-example.yaml.
touch obs-statefulset-example.yaml
vi obs-statefulset-example.yaml
Configuration example:
apiVersion: apps/v1 kind: StatefulSet metadata: name: obs-statefulset-example namespace: default spec: replicas: 1 selector: matchLabels: app: obs-statefulset-example template: metadata: labels: app: obs-statefulset-example spec: volumes: - name: pvc-obs-example persistentVolumeClaim: claimName: pvc-obs-example containers: - name: container-0 image: 'nginx:latest' volumeMounts: - name: pvc-obs-example mountPath: /tmp restartPolicy: Always imagePullSecrets: - name: default-secret serviceName: obs-statefulset-example-headless # Name of the headless Service
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.
Example of mounting an OBS volume to a StatefulSet (PVC template-based, dedicated volume):
Example YAML:
apiVersion: apps/v1 kind: StatefulSet metadata: name: obs-statefulset-example namespace: default spec: replicas: 1 selector: matchLabels: app: obs-statefulset-example template: metadata: labels: app: obs-statefulset-example spec: containers: - name: container-0 image: 'nginx:latest' volumeMounts: - name: pvc-obs-auto-example mountPath: /tmp restartPolicy: Always imagePullSecrets: - name: default-secret volumeClaimTemplates: - metadata: name: pvc-obs-auto-example namespace: default annotations: everest.io/obs-volume-type: STANDARD spec: accessModes: - ReadWriteMany resources: requests: storage: 1Gi storageClassName: csi-obs serviceName: obs-statefulset-example-headless
- Create a StatefulSet.
kubectl create -f obs-statefulset-example.yaml
Verifying Persistent Storage of an OBS Volume
- Query the pod and OBS volume of the deployed workload (for example, obs-statefulset-example).
- Run the following command to query the pod name of the workload:
kubectl get po | grep obs-statefulset-example
Expected outputs:
obs-statefulset-example-0 1/1 Running 0 2m5s
- Run the following command to check whether an OBS volume is mounted to the /tmp directory:
kubectl exec obs-statefulset-example-0 -- mount|grep /tmp
Expected outputs:
s3fs on /tmp type fuse.s3fs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other)
- Run the following command to query the pod name of the workload:
- Run the following command to create a file named test in the /tmp directory:
kubectl exec obs-statefulset-example-0 -- touch /tmp/test
- Run the following command to view the file in the /tmp directory:
kubectl exec obs-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 obs-statefulset-example-0:
kubectl delete po obs-statefulset-example-0
- Check whether the file still exists after the pod is rebuilt.
- Run the following command to query the name of the rebuilt pod:
kubectl get po
Expected outputs:
obs-statefulset-example-0 1/1 Running 0 2m
- Run the following command to view the file in the /tmp directory:
kubectl exec obs-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 OBS volume can be persistently stored.
- Run the following command to query the name of the rebuilt pod:
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