Kubernetes : Use External Storage2022/11/02

Configure Persistent Storage in Kubernetes Cluster.

This example is based on the environment like follows.

For example, run NFS Server on Control Plane Node and configure Pods can use NFS area as external storage.

-----------+---------------------------+--------------------------+------------
           |                           |                          |
       eth0|10.0.0.25              eth0|10.0.0.71             eth0|10.0.0.72
+----------+-----------+   +-----------+-----------+   +-----------+-----------+
|  [ ctrl.srv.world ]  |   |  [snode01.srv.world]  |   |  [snode02.srv.world]  |
|     Control Plane    |   |      Worker Node      |   |      Worker Node      |
+----------------------+   +-----------------------+   +-----------------------+

[1]	Run NFS Server on Control Plane Node, refer to here. On this example, configure [/home/nfsshare] directory as NFS share.
[2]	Create PV (Persistent Volume) object and PVC (Persistent Volume Claim) object on Control Plane Node.

# create PV definition

root@ctrl:~#

vi nfs-pv.yml

apiVersion: v1
kind: PersistentVolume
metadata:
  # any PV name
  name: nfs-pv
spec:
  capacity:
    # storage size
    storage: 10Gi
  accessModes:
    # Access Modes:
    # - ReadWriteMany (RW from multi nodes)
    # - ReadWriteOnce (RW from a node)
    # - ReadOnlyMany (R from multi nodes)
    - ReadWriteMany
  persistentVolumeReclaimPolicy:
    # retain even if pods terminate
    Retain
  nfs:
    # NFS server's definition
    path: /home/nfsshare
    server: 10.0.0.25
    readOnly: false

root@ctrl:~#

kubectl create -f nfs-pv.yml

persistentvolume "nfs-pv" created
root@ctrl:~#

kubectl get pv

NAME     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
nfs-pv   10Gi       RWX            Retain           Available                                   5s

# create PVC definition

root@ctrl:~#

vi nfs-pvc.yml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  # any PVC name
  name: nfs-pvc
spec:
  accessModes:
  - ReadWriteMany
  resources:
     requests:
       storage: 10Gi

root@ctrl:~#

kubectl create -f nfs-pvc.yml

persistentvolumeclaim "nfs-pvc" created
root@ctrl:~#

kubectl get pvc

NAME      STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
nfs-pvc   Bound    nfs-pv   10Gi       RWX                           11s

[3]	Create Pods with PVC above.

root@ctrl:~#

vi nginx-nfs.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  # any Deployment name
  name: nginx-nfs
  labels:
    name: nginx-nfs
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx-nfs
  template:
    metadata:
      labels:
        app: nginx-nfs
    spec:
      containers:
      - name: nginx-nfs
        image: nginx
        ports:
          - name: web
            containerPort: 80
        volumeMounts:
          - name: nfs-share
            # mount point in container
            mountPath: /usr/share/nginx/html
      volumes:
        - name: nfs-share
          persistentVolumeClaim:
            # PVC name you created
            claimName: nfs-pvc

root@ctrl:~#

kubectl create -f nginx-nfs.yml

deployment.apps/nginx-nfs created

root@ctrl:~#

kubectl get pods -o wide

NAME                         READY   STATUS    RESTARTS   AGE   IP                NODE                NOMINATED NODE   READINESS GATES
nginx-nfs-7c7d5d4896-k2kn4   1/1     Running   0          93s   192.168.186.68    snode01.srv.world   <none>           <none>
nginx-nfs-7c7d5d4896-stkkq   1/1     Running   0          93s   192.168.186.67    snode01.srv.world   <none>           <none>
nginx-nfs-7c7d5d4896-z8898   1/1     Running   0          94s   192.168.211.130   snode02.srv.world   <none>           <none>

root@ctrl:~#

kubectl expose deployment nginx-nfs --type="NodePort" --port 80

service/nginx-nfs exposed
root@ctrl:~#

kubectl get service nginx-nfs

NAME        TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
nginx-nfs   NodePort   10.104.124.105   <none>        80:32037/TCP   5s

# create a test file under the NFS shared directory

root@ctrl:~#

echo 'NFS Persistent Storage Test' > /home/nfsshare/index.html

# verify accesses

root@ctrl:~#

curl 10.104.124.105

NFS Persistent Storage Test

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