How to Configure Rolling Update in Kubernetes

Kubernetes, the open-source container orchestration platform, empowers developers to deploy, scale, and manage containerized applications effortlessly. One crucial aspect of maintaining applications in Kubernetes is ensuring seamless updates without downtime. In this guide, we'll explore the concept of rolling updates and provide step-by-step instructions on how to configure them in Kubernetes.

Understanding Rolling Updates in Kubernetes:

Rolling updates enable the deployment of new versions of an application while gracefully transitioning from the old version to the new one. This ensures that your application remains available and responsive throughout the update process, minimizing user impact.

Prerequisites:

Before diving into the configuration, make sure you have the following prerequisites in place:

1. A running Kubernetes cluster.
2. kubectl command-line tool installed and configured to communicate with your cluster.

Configuring Rolling Updates:

Step 1: Update Your Kubernetes Deployment Manifest:

To initiate a rolling update, you need to modify your deployment manifest file. Open the file using your preferred text editor. Locate the container image tag or version you want to update and replace it with the new one.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: your-app-deployment
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: your-app
    spec:
      containers:
      - name: your-app-container
        image: your-app-image:v2.0  # Update this to the new version
        ports:
        - containerPort: 80

Step 2: Apply the Updated Manifest:

Save the changes to your deployment manifest file and apply the update using the following kubectl command:

kubectl apply -f your-updated-manifest.yaml

Step 3: Monitor the Rolling Update:

Keep an eye on the update progress by monitoring the rollout status:

kubectl rollout status deployment/your-app-deployment

This command displays the status of the rollout, indicating whether it's in progress or has been successfully completed.

Step 4: Rollback (if needed):

In case something goes wrong during the update, Kubernetes allows you to roll back to the previous version:

kubectl rollout undo deployment/your-app-deployment

More Examples and Advanced Configurations:

Blue-Green Deployment:

For a more advanced strategy, consider implementing a blue-green deployment, where you maintain two identical environments, one with the current version (blue) and the other with the new version (green). This allows for quick and safe switching between versions.

# Blue service
apiVersion: v1
kind: Service
metadata:
  name: blue-service
spec:
  selector:
    app: your-app
    color: blue
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
---
# Green service
apiVersion: v1
kind: Service
metadata:
  name: green-service
spec:
  selector:
    app: your-app
    color: green
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080

Configuring rolling updates in Kubernetes is an essential skill for ensuring the smooth operation of your containerized applications. By following these steps and exploring advanced deployment strategies, you can deploy updates seamlessly and maintain a robust and responsive application environment.