How to set pvc with statefulset in kubernetes? - 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?

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