Persistent NFS volumes with Kubernetes

Persistent Volumes in Kubernetes

In this example we will create a persistent Volume, followed by a persistent volume claim, then create an nginx pod that will mount the volume we created
As this is my home environment, I have an Ubuntu server sharing and NFS filesystem over running on ZFS
Check for PV
kubectl get pv
No resources found in default namespace.
Check for PVC
kubectl get pvc
No resources found in default namespace.
  • Create the yaml file
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-nfs1
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteMany
  nfs:
    server: 192.168.0.240
    path: "/mypool/data1"
  • Create the PV
kubectl create -f nfspv.yaml
persistentvolume/pv-nfs1 created

kubectl get pv
NAME      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
pv-nfs1   5Gi        RWX            Retain           Available           manual                  14s
  • Create the PVC yaml file
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pv-nfs1
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 2Gi
  • Create the PVC
kubectl create -f nfs-pvc.yaml
persistentvolumeclaim/pv-nfs1 created

kubectl get pvc
NAME      STATUS   VOLUME    CAPACITY   ACCESS MODES   STORAGECLASS   AGE
pv-nfs1   Bound    pv-nfs1   5Gi        RWX            manual         14s
  • Create the nginx yaml file, note the pvc volume pv-nfs1
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    run: nginx
  name: mynginx
spec:
  replicas: 1
  selector:
    matchLabels:
      run: nginx
  template:
    metadata:
      labels:
        run: nginx
    spec:
      volumes:
      - name: www
        persistentVolumeClaim:
          claimName: pv-nfs1
      containers:
      - image: nginx
        name: nginx
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  • Create the nginx pod
kubectl create -f deploynfs.yaml
deployment.apps/mynginx created

kubectl get deployments
NAME      READY   UP-TO-DATE   AVAILABLE   AGE
mynginx   1/1     1            1           27s
  • Get the name of the new POD
kubectl get all
NAME                           READY   STATUS    RESTARTS   AGE
pod/mynginx-58854674df-vnrgp   1/1     Running   0          2m20s

NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
service/kubernetes   ClusterIP   10.96.0.1               443/TCP          4d1h
service/mynginx      NodePort    10.111.183.18           80:32443/TCP     4d
service/oracle12c    NodePort    10.109.93.8             1521:30759/TCP   24h

NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/mynginx   1/1     1            1           2m20s

NAME                                 DESIRED   CURRENT   READY   AGE
replicaset.apps/mynginx-58854674df   1         1         1       2m20s
  • Fine out which workder node the container is running on ( worker2 )
kubectl describe pod mynginx-58854674df-vnrgp
Name:         mynginx-58854674df-vnrgp
Namespace:    default
Priority:     0
Node:         worker2.localdomain/192.168.0.232
Start Time:   Tue, 28 Apr 2020 21:22:26 +1000
Labels:       pod-template-hash=58854674df
              run=nginx
  • SSH into worker 2 and check the filesystem is mounted
mount|grep data
192.168.0.240:/mypool/data1 on /var/lib/kubelet/pods/10906cfd-ff44-4970-83d0-7c558d88acd4/volumes/kubernetes.io~nfs/pv-nfs1
  • Log into the Container and confirm nginx is running on the Persistent volume
docker exec -it f3122341bb94 bash
root@mynginx-58854674df-vnrgp:/# df -k
Filesystem                   1K-blocks    Used  Available Use% Mounted on
overlay                       37722116 7164592   30557524  19% /
tmpfs                            65536       0      65536   0% /dev
tmpfs                          4987368       0    4987368   0% /sys/fs/cgroup
/dev/mapper/ol-root           37722116 7164592   30557524  19% /etc/hosts
shm                              65536       0      65536   0% /dev/shm
192.168.0.240:/mypool/data1 1450573824       0 1450573824   0% /usr/share/nginx/html
tmpfs                          4987368      12    4987356   1% /run/secrets/kubernetes.io/serviceaccount
tmpfs                          4987368       0    4987368   0% /proc/acpi
tmpfs                          4987368       0    4987368   0% /proc/scsi
tmpfs                          4987368       0    4987368   0% /sys/firmware
  • check to make sure nginx web server is running
curl worker2.localdomain:32443

 It worked!!
NOTE To get the port the nginx server is runnig on, run the following command ( 80:32443 )
kubectl get all -o wide
NAME                           READY   STATUS    RESTARTS   AGE     IP            NODE                  NOMINATED NODE   READINESS GATES
pod/mynginx-58854674df-vnrgp   1/1     Running   0          9m18s   172.17.2.17   worker2.localdomain              

NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE    SELECTOR
service/kubernetes   ClusterIP   10.96.0.1               443/TCP          4d1h   
service/mynginx      NodePort    10.111.183.18           80:32443/TCP     4d     run=nginx

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