Updating and Rolling Back Applications in GKE - Tutorial
Updating and rolling back applications is a critical aspect of managing containerized workloads in Google Kubernetes Engine (GKE). Being able to deploy new versions of your applications and revert to previous versions is essential for maintaining application health and continuous delivery. This tutorial will guide you through the process of updating and rolling back applications in GKE.
Prerequisites
Before getting started with updating and rolling back applications in GKE, ensure you have the following:
- A Google Cloud Platform (GCP) project with the necessary permissions
- A configured Kubernetes cluster in Google Kubernetes Engine
- An existing deployment or application running in your cluster
Steps to Update and Roll Back Applications
Follow these steps to update and roll back applications in GKE:
Step 1: Build a new version of your application
Build a new version of your application, such as updating the container image, modifying the code, or changing the configuration. Ensure that the new version is ready to be deployed.
Step 2: Update the deployment manifest
Update the deployment manifest to reference the new version of your application. You can modify the image tag, environment variables, or any other relevant fields in the manifest. Here's an example:
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-app
spec:
replicas: 3
template:
spec:
containers:
- name: my-container
image: my-registry/my-app:2.0
# Other configuration options
Step 3: Apply the updated manifest
Apply the updated deployment manifest to your cluster using the kubectl apply command:
kubectl apply -f deployment.yaml
Step 4: Verify the rollout status
Check the status of the rollout to ensure that the new version of your application is being deployed successfully:
kubectl rollout status deployment/my-app
Step 5: Roll back to a previous version
If necessary, you can roll back to a previous version of your application. Specify the revision you want to roll back to using the kubectl rollout undo command:
kubectl rollout undo deployment/my-app --to-revision=1
Common Mistakes to Avoid
- Not thoroughly testing the new version of the application before deployment.
- Overlooking the need to update the deployment manifest, resulting in incorrect configurations.
- Skipping the verification step, which may lead to undetected issues in the rollout process.
Frequently Asked Questions (FAQs)
-
What happens during a rollout in Kubernetes?
During a rollout, Kubernetes creates new replicas with the updated configuration and gradually replaces the existing instances to ensure a smooth transition.
-
How can I track the progress of a rollout?
You can track the progress of a rollout by using the
kubectl rollout statuscommand, which provides information on the deployment's current status. -
Can I perform a rolling update with zero downtime?
Yes, Kubernetes supports rolling updates, which allow you to update your application without causing downtime by gradually transitioning between old and new instances.
-
What happens to the existing instances during a rollback?
During a rollback, Kubernetes terminates the new instances and replaces them with the previous version, ensuring a seamless transition to the older version of the application.
-
Can I roll back to a specific revision?
Yes, you can roll back to a specific revision of your application by specifying the revision number using the
kubectl rollout undocommand.
Summary
In this tutorial, you learned how to update and roll back applications in Google Kubernetes Engine (GKE). By building a new version of your application, updating the deployment manifest, applying the changes, and verifying the rollout status, you can successfully update your applications. Additionally, you explored how to roll back to a previous version if needed. Remember to avoid common mistakes and thoroughly test your application updates before deployment. Managing application updates and rollbacks is crucial for maintaining the stability and reliability of your applications in GKE.