How to Fix Docker Build Failures in GitHub Actions When Deploying Your App

Discover how to resolve the common issue of `Docker build` failures in GitHub Actions. Learn the steps to ensure your build artifacts are available across jobs for a successful deployment.
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How to Fix Docker Build Failures in GitHub Actions When Deploying Your App

Are you facing a frustrating hurdle in your GitHub Actions workflow? If you’re trying to run NPM scripts, create a Docker image, and publish it to DockerHub, you might encounter the dreaded build failure that says: "COPY failed: file not found in build context or excluded by .dockerignore." This error message commonly indicates that the build directory is missing in the context when Docker tries to build the image.

In this guide, we will break down the core issue and provide an effective solution to ensure that your builds work seamlessly from one job to the next in GitHub Actions.

Understanding the Problem

The error you might be getting commonly originates from the separation of jobs in GitHub Actions. When you have multiple jobs, each job starts with a fresh environment. This means that any build artifacts created in the first job (like the build directory) aren't automatically available in the subsequent job. As a result, when the deployment job tries to access the build directory, it's simply not there.

Your Current Workflow

Here’s a glimpse of your current GitHub Actions workflow:

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

What Went Wrong?

The core issue arises here:

You successfully build your app and create the necessary files in the first job.

However, when the second job runs, it does not have access to those artifacts, thus resulting in an error when Docker attempts to copy the files that should reside in the build directory.

The Solution: Use Artifacts to Share Data Between Jobs

To fix the issue, you can leverage GitHub Actions’ built-in capabilities to upload and download artifacts. This way, you can store the output of your first job and retrieve it in the second job. Here’s how to implement it step-by-step.

Updated Workflow

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

Key Changes Made

Upload Artifact in Build Job: After building your app, upload the build directory as an artifact.

Download Artifact in Deploy Job: In the deploy job, download the artifact before building the Docker image.

Conclusion

By implementing the above changes using actions/upload-artifact and actions/download-artifact, you can ensure your build artifacts are carried over between the jobs in your GitHub Actions workflow. This will fix the Docker build failures you've been experiencing and streamline your deployment process.

Now you can focus on what really matters – building your application and getting it into production! If you found this article helpful, don’t hesitate to share it with your fellow developers.