MicroK8s : Use External Storage2023/06/22

	Configure External Storage in MicroK8s. For example, it uses NFS server for it.
[1]	Configure NFS Server on any node, refer to here. On ths example, it uses [/home/nfsshare] directory on NFS Server that is running on [nfs.srv.world (10.0.0.35)].
[2]	Create PV (Persistent Volume) object and PVC (Persistent Volume Claim) object.

# create PV definition

root@dlp:~#

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
  storageClassName: nfs-server
  nfs:
    # NFS server's definition
    path: /home/nfsshare
    server: 10.0.0.35
    readOnly: false

root@dlp:~#

microk8s kubectl apply -f nfs-pv.yml

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

microk8s kubectl get pv

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

# create PVC definition

root@dlp:~#

vi nfs-pvc.yml

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

root@dlp:~#

microk8s kubectl apply -f nfs-pvc.yml

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

microk8s kubectl get pvc

NAME      STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
nfs-pvc   Bound    nfs-pv   10Gi       RWX            nfs-server     5s

[3]	Create Pods with PVC above.

root@dlp:~#

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@dlp:~#

microk8s kubectl apply -f nginx-nfs.yml

deployment.apps/nginx-nfs created

root@dlp:~#

microk8s kubectl get pods -o wide

NAME                         READY   STATUS    RESTARTS   AGE     IP            NODE               NOMINATED NODE   READINESS GATES
nginx-nfs-5bb7fbc8fb-mhs5n   1/1     Running   0          3m25s   10.1.142.73   dlp.srv.world      <none>           <none>
nginx-nfs-5bb7fbc8fb-vxkzd   1/1     Running   0          3m25s   10.1.40.197   node01.srv.world   <none>           <none>
nginx-nfs-5bb7fbc8fb-v9fx9   1/1     Running   0          3m25s   10.1.40.198   node01.srv.world   <none>           <none>

root@dlp:~#

microk8s kubectl expose deployment nginx-nfs --type="NodePort" --port 80

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

microk8s kubectl get service nginx-nfs

NAME        TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
nginx-nfs   NodePort   10.152.183.161   <none>        80:30887/TCP   6s

# on NFS server, create a test file under the NFS shared directory

root@nfs:~#

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

# verify accesses on a node which users can access to microk8s cluster

root@dlp:~#

curl 10.152.183.161

NFS Persistent Storage Test

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