Update Management

1. Introduction

Welcome to this tutorial! Our goal is to learn how to manage updates in Kubernetes, focusing on performing Rolling Updates. With Rolling Updates, we can update the version of the application without any downtime.

By the end of this tutorial, you will learn:
- How to perform Rolling Updates in Kubernetes
- How to revert to previous versions if needed
- Best practices for managing updates

Prerequisites:
- Basic understanding of Kubernetes
- Kubernetes and kubectl installed on your system
- Basic understanding of Docker and Containers

2. Step-by-Step Guide

Rolling updates are the default strategy to update the running version of your app in Kubernetes. This means that the update will be done pod by pod, ensuring zero downtime during the application update.

To perform a rolling update, use the kubectl set image command, followed by the deployment name and the new image version.

Tips:
- Always test the new version of your application before deploying it into the production environment.
- Regularly backup your Kubernetes cluster's state using tools like Velero.

3. Code Examples

• Here's an example of how to update your application:

# Update the version of the application
kubectl set image deployments/myapp-deployment myapp=nginx:1.16.1

In this command:
- deployments/myapp-deployment is the name of your Deployment.
- myapp=nginx:1.16.1 specifies that the nginx version 1.16.1 should replace the current version.

The expected output will be the updated deployment in which the new pods start running and old pods terminate gradually.

• To check the status of the rollout, use this command:

kubectl rollout status deployments/myapp-deployment

• If something goes wrong with the new version, you can revert to the previous version using the rollout undo command:

kubectl rollout undo deployments/myapp-deployment

4. Summary

In this tutorial, we learned how to perform rolling updates in Kubernetes, how to check the status of these updates, and how to revert to the previous version of the application if something goes wrong.

For further learning, explore how to automate the update process using CI/CD pipelines, and how to monitor your applications in Kubernetes.

5. Practice Exercises

1. Create a new deployment with an image of your choice and perform a rolling update to a new version.
2. Check the status of the rollout. If it's not successful, try to identify the issue and fix it.
3. Practice rolling back to a previous version of your application.

Remember, practice is key to mastering any concept. Continue to explore and experiment with different scenarios and configurations. Good luck!