README.md

Persistent Volume and Persistent Volume Claim

Persistent Volume and Persistent Volume Claim
Reserving a Persistent Volume
Tips and Tricks

For simulated Practice problems visit KillerCoda.

1. Create a persistent Volume name pv-1808 with the following details:

   • storageClassName: ""
   • capacity.storage: 1Gi
   • volumeModes: FileSystem
   • accessModes: ReadWriteMany
   • hostPath: /data
   Solution

   # create pv.yaml
   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: pv-1808
   spec:
     capacity:
       storage: 1Gi
     volumeMode: Filesystem
     accessModes:
       - ReadWriteMany
     persistentVolumeReclaimPolicy: Recycle
     storageClassName: ""
     hostPath:
       path: /data
   
   
   # create persistent volume
   k create -f pv.yaml

2. Create a persistent Volume claim name pvc-1808 in namespace ns-1808, binding to pv-1808 with the following details:

   • storageClassName: ""
   • capacity.storage: 1Gi
   • volumeModes: FileSystem
   • accessModes: ReadWriteMany
   Solution

   # check for the ns-1808 namespace
   k get ns
   
   # create if it does not exist
   k create ns ns-1808
   
   # create pvc.yaml
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: pvc-1808
     namespace: ns-1808
   spec:
     accessModes:
       - ReadWriteMany
     volumeMode: Filesystem
     resources:
       requests:
         storage: 1Gi
     storageClassName: ""
     volumeName: pv-1808
   
   
   # create persistent volume
   k create -f pvc.yaml
   
   # check pvc status to be binded
   k get pvc -n ns-1808

3. Run pod pd-1808 with image nginx:alpine in namespace ns-1808 mounting pvc pvc-1808 as volume named mydata at mount path /tedi, run a command echo "It feels awsome to prepare for CKAD" > /tedi/author.txt.

   Solution

   export dr="--dry-run=client -o yaml"
   
   # generate pod.yaml
   k run pd-1808 --image=nginx:alpine $dr > pod.yaml
   
   # update pod.yaml
   apiVersion: v1
   kind: Pod
   metadata:
     creationTimestamp: null
     labels:
       run: pd-1808
     name: pd-1808
     namespace: ns-1808
   spec:
     volumes:
       - name: mydata
         persistentVolumeClaim:
           claimName: pvc-1808
     containers:
     - image: nginx:alpine
       name: pd-1808
       command: ["sh","-c","echo 'It feels awsome to prepare for CKAD' > /tedi/author.txt"]
       volumeMounts:
         - name: mydata
           mountPath: /tedi
     dnsPolicy: ClusterFirst
     restartPolicy: Always
   
   # now to verify that our text is persisted on the host storage
   # check node on which pod is scheduled
   k describe po pd-1808 -n ns-1808 | grep -i node
   
   # ssh to that node
   ssh <node-name>
   
   # check file contents
   cat /data/author.txt

4. Create a persistent Volume name lv-vol with storage capacity 1Gi, mounting at /inventory and accessModes RWO, bind it to a claim name lv-vol-claim and mount it on a busybox pod name busy running command sleep 3600 in namespace default.

   Solution

   # create pv.yaml
   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: lv-vol
     namespace: default
   spec:
     capacity:
       storage: 1Gi
     volumeMode: Filesystem
     accessModes:
       - ReadWriteOnce
     persistentVolumeReclaimPolicy: Recycle
     hostPath:
       path: /inventory
   
   # create persistent volume claim
   k create -f pv.yaml
   
   # create pvc.yaml
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: lv-vol-claim
     namespace: default
   spec:
     accessModes:
       - ReadWriteOnce
     volumeMode: Filesystem
     resources:
       requests:
         storage: 1Gi
     volumeName: lv-vol
   
   
   # create persistent volume claim
   k create -f pvc.yaml
   
   
   # mount it to a pod
   apiVersion: v1
   kind: Pod
   metadata:
     creationTimestamp: null
     labels:
       run: busy
     name: busy
     namespace: default
   spec:
     volumes:
       - name: data
         persistentVolumeClaim:
           claimName: lv-vol-claim
     containers:
     - image: busybox
       name: busy
       resources: {}
       command: ["sh","-c","sleep 3600"]
       volumeMounts:
         - name: data
           mountPath: /log
     dnsPolicy: ClusterFirst
     restartPolicy: Always

5. create a rare pod with image nginx:alpine mounting an emptyDir volume called pdata at /usr/share/data.

   Solution

   export do="--dry-run=client -o yaml"
   
   # generate pod.yaml
   k run rare --image=nginx:alpine $dr > pod.yaml
   
   # update pod.yaml
   apiVersion: v1
   kind: Pod
   metadata:
     creationTimestamp: null
     labels:
       run: rare
     name: rare
   spec:
     volumes:
       - name: pdata
         emptyDir: {}
     containers:
     - image: nginx:alpine
       name: rare
       volumeMounts:
         - name: pdata
           mountPath: /usr/share/data
     dnsPolicy: ClusterFirst
     restartPolicy: Always
   
   # create the pod
   k create -f pod.yaml