Resolving Docker Image Deployment Failures to GKE with Jenkins

Learn how to troubleshoot and correct deployment issues when using Jenkins to deploy Docker images to Google Kubernetes Engine (GKE).
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This video is based on the question https://stackoverflow.com/q/64015503/ asked by the user 'DVader' ( https://stackoverflow.com/u/10163423/ ) and on the answer https://stackoverflow.com/a/64023334/ provided by the user 'PjoterS' ( https://stackoverflow.com/u/11148139/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting Docker Image Deployment to GKE Using Jenkins

When working with Jenkins and Google Kubernetes Engine (GKE), deploying Docker images can sometimes hit roadblocks that cause frustration and confusion. One common issue developers face is a failure in the "Deploy to K8s" stage, where Jenkins successfully builds the Docker image but fails to deploy it to GKE without displaying any clear error messages. In this guide, we'll dive into a user's dilemma and explore step-by-step solutions to resolve deployment errors effectively.

The Problem: Deployment Failure Without Error Messages

Our user is running the Jenkins jenkinsci/blueocean docker image on a Mac and is attempting to build and deploy a Docker image to a Kubernetes cluster in GCP using a Jenkins pipeline. The image builds correctly and is pushed to DockerHub, but the deployment fails during the Kubernetes stage. This leaves the user with a sense of uncertainty, as Jenkins provides no specific error message to pinpoint what went wrong.

Example Setup

The user's deployment configuration is defined in a deployment.yaml file, which describes how the application is structured. The key parts of the configuration are:

[[See Video to Reveal this Text or Code Snippet]]

The Jenkins pipeline script includes a step to deploy the application to Kubernetes:

[[See Video to Reveal this Text or Code Snippet]]

Identifying the Issue

Although everything seems proper with the configuration, running the kubectl apply command on the deployment reveals errors related to naming conventions required by Kubernetes. Kubernetes has strict rules regarding the naming of resources. According to the error messages received, the following issues arise from the user's configuration:

Invalid metadata.name: The name mywebtestApp-deployment includes uppercase letters, which is in violation of DNS-1123 naming requirements.

Invalid container name: Similarly, the container name mywebtestApp also contains uppercase letters and must follow the same lowercase guideline.

Solutions: Make the Necessary Changes

To resolve these issues and allow the deployment to succeed, we need to modify both the deployment name and the labels to use lowercase letters only. Here are the changes that need to be made:

Update the Deployment Name:

From name: mywebtestApp-deployment to name: mywebtestapp-deployment

Adjust the Label:

From app: mywebtestApp to app: mywebtestapp

Updated Configuration Example

With these changes applied, the corrected deployment.yaml will look like this:

[[See Video to Reveal this Text or Code Snippet]]

Deploying the Updated Configuration

To deploy the updated configuration, run the following command in your terminal:

[[See Video to Reveal this Text or Code Snippet]]

This should produce a reassuring response indicating that the deployment was successfully created:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following this guide, you can troubleshoot and resolve common deployment issues when deploying Docker images to GKE using Jenkins. Remember, Kubernetes naming conventions are strict, so always ensure your resource names are in lowercase to avoid deployment failures. With this knowledge in hand, you can enhance your CI/CD pipeline and deploy applications to Kubernetes with greater confidence!