# 7. State Persistence (8%)

### Defining and Mounting a PersistentVolume <a href="#defining_and_mounting_a_persistentvolume_0" id="defining_and_mounting_a_persistentvolume_0"></a>

1. Create a Persistent Volume named `pv`, access mode `ReadWriteMany`, storage class name `shared`, `512MB` of storage capacity and the host path `/data/config`.
2. Create a Persistent Volume Claim named `pvc` that requests the Persistent Volume in step 1. The claim should request `256MB`. Ensure that the Persistent Volume Claim is properly bound after its creation.
3. Mount the Persistent Volume Claim from a new Pod named `app` with the\
   path `/var/app/config`. The Pod uses the image `nginx`.
4. Check the events of the Pod after starting it to ensure that the\
   Persistent Volume was mounted properly.

答案：\
Create a YAML file for the Persistent Volume and create it with the command kubectl create command.\
参考官网：[configure-persistent-volume-storage](https://kubernetes.io/zh/docs/tasks/configure-pod-container/configure-persistent-volume-storage/)

```
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv
spec:
  capacity:
    storage: 512m
  accessModes:
    - ReadWriteMany
  storageClassName: shared
  hostPath:
    path: /data/config
```

You will see that the Persistent Volume has been created but and is available to be claimed.

$ kubectl get pv\
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE\
pv 512m RWX Retain Available shared 4s\
Create a YAML file for the Persistent Volume Claim and create it with the command kubectl create command.

```
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: pvc
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 256m
  storageClassName: shared
```

You will see that the Persisten Volume Claim has been created and has been bound to the Persisten Volume.

```
$ kubectl get pvc
NAME   STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
pvc    Bound    pv       512m       RWX            shared         2s

$ kubectl get pv
NAME   CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM         STORAGECLASS   REASON   AGE
pv     512m       RWX            Retain           Bound    default/pvc   shared                  1m
```

Create a YAML file for the Pod and create it with the command kubectl create command.

```
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: app
  name: app
spec:
  containers:
  - image: nginx
    name: app
    volumeMounts:
      - mountPath: "/var/app/config"
        name: configpvc
    resources: {}
  volumes:
    - name: configpvc
      persistentVolumeClaim:
        claimName: pvc
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}
```

You can check the events of a Pod with the kubectl describe command. You should see an entry that indicates the successful mount.

```
$ kubectl describe pod app
...
Events:
  Type    Reason                 Age   From                         Message
  ----    ------                 ----  ----                         -------
  Normal  Scheduled              16s   default-scheduler            Successfully assigned app to docker-for-desktop
  Normal  SuccessfulMountVolume  16s   kubelet, docker-for-desktop  MountVolume.SetUp succeeded for volume "pv"
  Normal  SuccessfulMountVolume  16s   kubelet, docker-for-desktop  MountVolume.SetUp succeeded for volume "default-token-fsmmp"
  Normal  Pulling                15s   kubelet, docker-for-desktop  pulling image "nginx"
  Normal  Pulled                 14s   kubelet, docker-for-desktop  Successfully pulled image "nginx"
  Normal  Created                14s   kubelet, docker-for-desktop  Created container
  Normal  Started                13s   kubelet, docker-for-desktop  Started container
```