How to set pvc with statefulset in kubernetes?

Question

On GKE, I set a statefulset resource as

---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: redis
spec:
  serviceName: "redis"
  selector:
    matchLabels:
      app: redis
  updateStrategy:
    type: RollingUpdate
  replicas: 3
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
      - name: redis
        image: redis
        resources:
          limits:
            memory: 2Gi
        ports:
          - containerPort: 6379
        volumeMounts:
          - name: redis-data
            mountPath: /usr/share/redis
      volumes:
        - name: redis-data
          persistentVolumeClaim:
            claimName: redis-data-pvc

Want to use pvc so created this one. (This step was did before the statefulset deployment)

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: redis-data-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi

When check the resource in kubernetes

kubectl get pvc
NAME             STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
redis-data-pvc   Bound    pvc-6163d1f8-fb3d-44ac-a91f-edef1452b3b9   10Gi       RWO            standard       132m

The default Storage Class is standard.

kubectl get storageclass
NAME                 PROVISIONER
standard (default)   kubernetes.io/gce-pd

But when check the statafulset's deployment status. It always wrong.

# Describe its pod details
...
Events:
  Type     Reason                  Age                From                     Message
  ----     ------                  ----               ----                     -------
  Warning  FailedScheduling        22s                default-scheduler        persistentvolumeclaim "redis-data-pvc" not found
  Warning  FailedScheduling        17s (x2 over 20s)  default-scheduler        pod has unbound immediate PersistentVolumeClaims (repeated 2 times)
  Normal   Created                 2s (x2 over 3s)    kubelet                  Created container redis
  Normal   Started                 2s (x2 over 3s)    kubelet                  Started container redis
  Warning  BackOff                 0s (x2 over 1s)    kubelet                  Back-off restarting failed container

Why can't it find the redis-data-pvc name?

Barrens

Add output of kubectl get pv -A – Wnw

Answer 1

What you have done, should work. Make sure that the PersistentVolumeClaim and the StatefulSet is located in the same namespace.

---

Thats said, this is an easier solution, and that let you easier scale up to more replicas:

When using StatefulSet and PersistentVolumeClaim, use the volumeClaimTemplates: field in the StatefulSet instead.

The volumeClaimTemplates: will be used to create unique PVCs for each replica, and they have unique naming ending with e.g. -0 where the number is an ordinal used for the replicas in a StatefulSet.

So instead, use a SatefuleSet manifest like this:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: redis
spec:
  serviceName: "redis"
  selector:
    matchLabels:
      app: redis
  updateStrategy:
    type: RollingUpdate
  replicas: 3
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
      - name: redis
        image: redis
        resources:
          limits:
            memory: 2Gi
        ports:
          - containerPort: 6379
        volumeMounts:
          - name: redis-data
            mountPath: /usr/share/redis
  volumeClaimTemplates:                     // this will be used to create PVC
  - metadata:
      name: redis-data
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 10Gi

Horseshit

Your comment is correct for Redis StatefulSet, but it's not necessarily true for any StatefulSet. Actually you can use both options, depending on your needs. If you need a separate PV for each pod then indeed you should use volumeClaimTemplates. But if your pods need to share a volume mount it's perfectly legal to use a regular PVC in ReadOnlyMany / ReadWriteMany mode (given that your storage drive supports this kind of access). – Octavalent

Thank you. It works. But I have an another question. How to do in this case? #65276512 If I want to do an install command when install container. – Barrens

Answer 2

For using exist multiple persistentvolume instead storageclass use selector, for sample:

  volumeClaimTemplates:
  - metadata:
      name: pvc-nginx
    spec:
      selector:
        matchLabels:
          app: nginx-tst-statefulset
      accessModes: [ "ReadWriteMany" ]
      resources:
        requests:
          storage: 10Mi
      storageClassName: ""

Karalee