💡Managing Persistent Volumes in Kubernetes.

🎯 What is a Persistent Volume (PV)?

• In Kubernetes, Persistent Volume (PV) is storage that keeps your data even if a pod is deleted or restarted.

• A Persistent Volume Claim (PVC) is like a request that an application makes to use this storage.

• Think of PV as a storage drive and PVC as asking for a piece of that drive for your app.

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🛠️ Task 1: Adding a Persistent Volume to Your Todo App Deployment

📌 Step 1: Create a Persistent Volume (PV) - pv.yml

📌 What does it do?

• This file creates storage in Kubernetes using a folder on your machine.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: todo-pv  # Name of the storage
spec:
  capacity:
    storage: 1Gi  # Total storage size (1 Gigabyte)
  accessModes:
    - ReadWriteOnce  # One node can write, multiple can read
  hostPath:
    path: "/mnt/data"  # Folder on your system to store data

✅ In simple terms:

• It creates 1GB storage at /mnt/data on the host system.

• Only one node can write, but others can read.

👉 Run this command to apply:

kubectl apply -f pv.yml

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📌 Step 2: Create a Persistent Volume Claim (PVC) - pvc.yml

📌 What does it do?

• The PVC requests storage from the PV for the app.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: todo-pvc  # Name of the storage request
spec:
  accessModes:
    - ReadWriteOnce  # Must match the PV
  resources:
    requests:
      storage: 500Mi  # Asking for 500MB of storage

✅ In simple terms:

• It asks for 500MB of storage from the available 1GB PV.

👉 Run this command to apply:

kubectl apply -f pvc.yml

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📌 Step 3: Update Deployment to Use PVC - deployment.yml

📌 What does it do?

• It mounts the storage so your app can use it.

volumes:
  - name: todo-storage
    persistentVolumeClaim:
      claimName: todo-pvc
containers:
  - name: todo-app
    volumeMounts:
      - mountPath: "/data"  # Inside the container
        name: todo-storage

✅ In simple terms:

• The storage is attached to the container at /data.

👉 Run this command to apply:

kubectl apply -f deployment.yml

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📌 Step 4: Verify That It Works

👉 Check if storage is created and connected:

kubectl get pv    # Check Persistent Volume  
kubectl get pvc   # Check Persistent Volume Claim  
kubectl get pods  # Check if the app is running

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🛠️ Task 2: Access Data in the Persistent Volume

📌 Step 1: Open the Pod’s Terminal

👉 Run this command to enter the running pod:

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

📌 Step 2: Save a File in the Persistent Volume

👉 Go to the storage folder inside the pod:

cd /data

👉 Create a test file:

echo "Hello Kubernetes!" > testfile.txt

📌 Step 3: Restart the Pod & Check if Data is Still There

👉 Delete the pod:

kubectl delete pod <pod-name>

👉 Check if a new pod starts:

kubectl get pods

👉 Enter the new pod and check the file:

kubectl exec -it <new-pod-name> -- /bin/bash
cat /data/testfile.txt

✅ If the file is still there, your Persistent Volume is working! 🎉