Day 36 Task: Managing Persistent Volumes in Your Deployment 💥

🙏 Introduction:

In this blog, we will explore Persistent Volumes & use Persistent Volumes in our deployment.

What are Persistent Volumes in k8s?

In Kubernetes, a Persistent Volume (PV) is a cluster-wide storage resource that can be used by pods to persist data beyond the lifetime of the pod. A Persistent Volume is a separate entity from the pod, and its lifecycle is managed independently from the pod.

A Persistent Volume is created by a cluster administrator and made available for use by the cluster's users. Once a Persistent Volume is created, it can be bound to a Persistent Volume Claim (PVC), which is a request for a specific amount of storage that a pod can use. When a pod requests storage using a PVC, the Kubernetes scheduler finds an available Persistent Volume that matches the request, binds the volume to the claim, and mounts the volume in the pod's container.

Many types of Persistent Volumes can be used in Kubernetes, including network-attached storage (NAS), storage area network (SAN), local storage, and cloud-based storage. Kubernetes also provides a plugin architecture for storage providers, allowing third-party storage systems to be integrated into the Kubernetes cluster.

💼Task :1

Add a Persistent Volume to your Deployment todo app

Steps:

1. 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"

1. Apply the Persistent Volume

kubectl apply -f pv.yml

1. 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

1. Apply the Persistent Volume Claim

kubectl apply -f pvc.yml

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

apiVersion: apps/v1
kind: Deployment
metadata:
  name: todo-app-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: todo-app
  template:
    metadata:
      labels:
        app: todo-app
    spec:
      containers:
        - name: todo-app
          image: sutish/django-todo-cicd:latest
          ports:
            - containerPort: 8000
          volumeMounts:
            - name: todo-app-data
              mountPath: /app
      volumes:
        - name: todo-app-dat
          persistentVolumeClaim:
            claimName: pvc-todo-app

1. Apply the updated deployment

kubectl apply -f deployment.yml

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

kubectl get pods 
kubectl get pv

💼Task:2

Accessing data in the Persistent Volume

Steps:

1. Connect to a Pod in your Deployment

kubectl exec -it todo-app-deployment-6d86879976-jgmxs -- bash

1. Create a test file inside that pod

echo "adding data into the pod" >test.txt

Verify that you can access the data stored in the Persistent Volume from within the Pod

1. To verify that we can access the data stored, delete the pod we have used in the above step and create a new pod. Connect to the new pod and verify whether the same file exists.

kubectl delete -f deployment.yml
kubectl apply -f deployment.yml
kubectl get pods

👋 Conclusion :

In this blog, we cover Persistent Volume in Kubernetes & do hands-on Persistent Volume. In the next blog, we will cover some Kubernetes Important Interview Questions.

Thank you for reading!

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