Day 36 Task: Managing Persistent Volumes in Your Deployment 💥

What are Persistent Volumes in k8s

In Kubernetes, a Persistent Volume (PV) is a piece of storage in the cluster that has been provisioned by an administrator. A Persistent Volume Claim (PVC) is a request for storage by a user. The PVC references the PV, and the PV is bound to a specific node. Read official documentation of Persistent Volumes.

Today's tasks:

Task 1:

Add a Persistent Volume to your Deployment todo app.

Create a Persistent Volume using a file on your node.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-todo-app
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  hostPath:
    path: "/tmp/data"

Create a Persistent Volume Claim that references the Persistent Volume.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-todo-app
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 500Mi

Update your deployment.yml file to include the Persistent Volume Claim.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: todo-app-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: todo-app
  template:
    metadata:
      labels:
        app: todo-app
    spec:
      containers:
        - name: todo-app
          image: amana6420/node-todo-app
          ports:
            - containerPort: 8000
          volumeMounts:
            - name: todo-app-data
              mountPath: /app
      volumes:
        - name: todo-app-data
          persistentVolumeClaim:
            claimName: pvc-todo-app

Apply the updated deployment using the command: kubectl apply -f deployment.yml

kubectl apply -f pv.yml
kubectl apply -f pvc.yml
kubectl apply -f deployment.yml

Verify that the Persistent Volume has been added to your Deployment by checking the status of the Pods and Persistent Volumes in your cluster.

ubuntu@ip-172-31-60-234:~/90DaysOfDevOps/2023/day36/90DaysOfDevOps/2023/day36$ kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                  STORAGECLASS   REASON   AGE
pv-todo-app                                1Gi        RWO            Retain           Available                                                  45m
pvc-ee1d932e-68e2-435f-83d0-c34785fa84e4   500Mi      RWO            Delete           Bound       default/pvc-todo-app   standard                45m
ubuntu@ip-172-31-60-234:~/90DaysOfDevOps/2023/day36/90DaysOfDevOps/2023/day36$ kubectl get pods
NAME                                   READY   STATUS             RESTARTS         AGE
nginx                                  1/1     Running            2 (32m ago)      3d19h
todo-app-798ddcd497-j9sxx              1/1     Running            0                2m3s

Task 2:

Accessing data in the Persistent Volume -

kubectl exec -it <pod-name> -- /bin/bash

Now, even if we delete the pod, the pod is removed but the PVC remains and the data in the PV is retained.

Day 36 Task: Managing Persistent Volumes in Your Deployment 💥 - 90DaysOfDevOps

What are Persistent Volumes in k8s

Today's tasks:

Task 1:

Task 2: