Using PersistentVolumes in Kubernetes

Introduction

PersistentVolumes provide a way to treat storage as a dynamic resource in Kubernetes. This lab will allow you to demonstrate your knowledge of PersistentVolumes. You will mount some persistent storage to a container using a PersistentVolume and a PersistentVolumeClaim.

Solution

Log in to the server using the credentials provided:

ssh cloud_user@<PUBLIC_IP_ADDRESS>

Create a PersistentVolume That Allows Claim Expansion

1. Create a custom Storage Class by using ```vi localdisk.yml`.

2. Define the Storage Class by using:

   apiVersion: storage.k8s.io/v1 
   kind: StorageClass 
   metadata: 
     name: localdisk 
   provisioner: kubernetes.io/no-provisioner
   allowVolumeExpansion: true
   

3. Save and exit the file by hitting the ESC key and using :wq.

4. Finish creating the Storage Class by using kubectl create -f localdisk.yml.

5. Create the PersistentVolume by using vi host-pv.yml.

6. Define the PersistentVolume with a size of 1Gi by using:

   kind: PersistentVolume 
   apiVersion: v1 
   metadata: 
      name: host-pv 
   spec: 
      storageClassName: localdisk
      persistentVolumeReclaimPolicy: Recycle 
      capacity: 
         storage: 1Gi 
      accessModes: 
         - ReadWriteOnce 
      hostPath: 
         path: /var/output
   

7. Save and exit the file by hitting the ESC key and using :wq.

8. Finish creating the PersistentVolume by using kubectl create -f host-pv.yml.

9. Check the status of the PersistenVolume by using kubectl get pv.

Create a PersistentVolumeClaim

1. Start creating a PersistentVolumeClaim for the PersistentVolume to bind to by using vi host-pvc.yml.

2. Define the PersistentVolumeClaim with a size of 100Mi by using:

   apiVersion: v1 
   kind: PersistentVolumeClaim 
   metadata: 
      name: host-pvc 
   spec: 
      storageClassName: localdisk 
      accessModes: 
         - ReadWriteOnce 
      resources: 
         requests: 
            storage: 100Mi
   

3. Save and exit the file by hitting the ESC key and using :wq.

4. Finish creating the PersistentVolumeClaim by using kubectl create -f host-pvc.yml.

5. Check the status of the PersistentVolume and PersistentVolumeClaim to verify that they have been bound:

   kubectl get pv
   kubectl get pvc
   

Create a Pod That Uses a PersistentVolume for Storage

1. Create a Pod that uses the PersistentVolumeClaim by using vi pv-pod.yml.

2. Define the Pod by using:

   apiVersion: v1 
   kind: Pod 
   metadata: 
      name: pv-pod 
   spec: 
      containers: 
         - name: busybox 
           image: busybox 
           command: ['sh', '-c', 'while true; do echo Success! > /output/success.txt; sleep 5; done'] 
   

3. Mount the PersistentVolume to the /output location by adding the following, which should be level with the containers spec in terms of indentation:

   volumes: 
    - name: pv-storage 
      persistentVolumeClaim: 
         claimName: host-pvc
   

4. In the containers spec, below the command, set the list of volume mounts by using:

   volumeMounts: 
   - name: pv-storage 
     mountPath: /output 
   

5. Save and exit the file by hitting the ESC key and using :wq.

6. Finish creating the Pod by using kubectl create -f pv-pod.yml.

7. Check that the Pod is up and running by using kubectl get pods.

8. If you wish, you can log in to the worker node and verify the output data by using cat /var/output/success.txt.