On Day 36 of your #90DaysOfDevOps journey, we’re tackling an important part of Kubernetes: Persistent Volumes (PVs)

Let’s break this down and walk you through both tasks:

What are Persistent Volumes (PV) in Kubernetes?

Kubernetes Pods are ephemeral — which means data inside a Pod is lost when the Pod is deleted or restarted. To persist data beyond the lifecycle of a Pod, we use:

• Persistent Volumes (PV): Storage resource in the cluster, provisioned by admins or dynamically via StorageClass.

• Persistent Volume Claims (PVC): A request for storage by a user or app.

• Deployment + PVC: Your app (e.g., the ToDo app) can claim storage by referencing a PVC.

Task 1: Add Persistent Volume to Your Deployment

Let’s go step-by-step.

1. Create a Persistent Volume (pv.yml)

apiVersion: v1

kind: PersistentVolume

metadata:

name: todo-pv

spec:

capacity:

storage: 1Gi

accessModes:

- ReadWriteOnce

hostPath:

path: /mnt/data

This creates a 1Gi volume using the hostPath /mnt/data on the node (local path for testing).

1. Create a Persistent Volume Claim (pvc.yml)

apiVersion: v1

kind: PersistentVolumeClaim

metadata:

name: todo-pvc

spec:

accessModes:

- ReadWriteOnce

resources:

requests:

storage: 1Gi

This PVC will bind to the todo-pv if the specs match.

1. Update your deployment.yml to use the PVC

Here’s the updated Deployment with volume mounting:

apiVersion: apps/v1

kind: Deployment

metadata:

name: todo-app

spec:

replicas: 1

selector:

matchLabels:

app: todo

template:

metadata:

labels:

app: todo

spec:

containers:

- name: todo-container

image: your-todo-app-image

volumeMounts:

- name: todo-storage

mountPath: /app/data

volumes:

- name: todo-storage

persistentVolumeClaim:

claimName: todo-pvc

Make sure:

•image: your-todo-app-image is replaced with your actual image.

•/app/data is where your app stores persistent data.

1. Apply the files

kubectl apply -f pv.yml

kubectl apply -f pvc.yml

kubectl apply -f deployment.yml

1. Verify Everything

kubectl get pv

kubectl get pvc

kubectl get pods

Look for STATUS: Bound on the PVC and Running pods.

Task 2: Access Data Inside the Pod

1. Connect to the Pod

kubectl get pods # get pod name

kubectl exec -it -- /bin/bash

1. Verify Data Access

cd /app/data

ls -l

OR

cat

You should see files created or used by your app.

Optional: Test Persistence

1. Delete the pod:

kubectl delete pod

2.  A new pod will be created (Deployment ensures this).

3.  Check if data is still present by repeating the steps to access /app/data.

You have Created and attached a Persistent Volume.