Day 36: Managing Persistent Volume in Deployment

🙌 Congratulations to you for conquering ConfigMaps and Secrets in Kubernetes yesterday.

🔥 You're on fire! 🔥

What is Persistent Volume in K8s?

Persistent Volume (PV) is a storage resource that can be dynamically provisioned or manually configured to provide storage to applications running in the cluster. Persistent Volumes decouple storage provision from the application, making it easier to manage and share storage resources in a cluster.

Key-points

It allows you to define and manage storage resources independently of the applications that use them.
It has a life cycle that includes the creation, deletion and management of storage resources.
It provides storage that persists data even if the application or pod using it is terminated or rescheduled.
PVs support different access modes, such as ReadWriteOnce (RWO), ReadOnlyMany (ROX), and ReadWriteMany (RWX), to accommodate various use cases.

TASK 1

Add a Persistent Volume to your Deployment todo app.

Create a Persistent Volume using a file on your node.

Create a Persistent Volume Claim that references the Persistent Volume.

Update your deployment.yml file to include the Persistent Volume Claim. After Applying pv.yml pvc.yml your deployment file.

Apply the updated deployment using the command.

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

Steps:

Create a persistent volume file and add the following content to it

  #persistentvolume.yml
  apiVersion: v1
  kind: PersistentVolume
  metadata:
    name: todo-app-pv
    namespace: my-app
  spec:
    capacity:
      storage: 1Gi
    accessModes:
      - ReadWriteOnce
    hostPath:
      path: /path/to/your/host

Give the path to your host in the hostPath section. And apply it to the Kubernetes Cluster by using the command

  kubectl apply -f persistentvolume.yml -n my-app

Claim the persistent volume by creating the persistent volume claim file and adding the content to it

  #persistentvolumeclaim.yml
  apiVersion: v1
  kind: PersistentVolumeClaim
  metadata:
    name: todo-app-pvc
    namespace: my-app
  spec:
    accessModes:
      - ReadWriteOnce
    resources:
     requests:
       storage: 1Gi

Apply PVC to your cluster

  kubectl apply -f persistentvolumeclaim.yml -n my-app

Update deployment file

  #deployment.yml
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: todo-app
    namespace: my-app
  spec:
    replicas: 1
    template:
      metadata:
        labels:
          app: todo-app
      spec:
        containers:
          - name: todo-app-container
            image: your-image:tag
            ports:
              - containerPort: 80
            volumeMounts:
              - name: persistent-volume-claim
                mountPath: /path/in/container
        volumes:
          - name: persistent-volume-claim
            persistentVolumeClaim:
              claimName: todo-app-pvc

Add your actual image tag and mountPath.

Apply the updated deployment file to the cluster
```
  kubectl apply -f deployment.yml -n my-app
```
Verify that the persistent volume was added successfully to the deployment by checking the status of pods and persistent volumes:
```
  #to check the status of pods
  kubectl get pods -n my-app

  #to check the status of persistent volume
  kubectl get pv -n my-app
```
Make sure that the pods are running and persistent volume is in a bound state.

TASK 2

Accessing data in the Persistent Volume,

Connect to a Pod in your Deployment using the command.

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