Migrating from Jenkins to GitHub Actions

In the rapidly evolving world of DevOps, continuous integration and continuous deployment (CI/CD) pipelines are essential for maintaining a streamlined development process. We recently migrated our applications from Jenkins-based pipelines to GitHub Actions workflows. This blog explores our journey of migrating from Jenkins to GitHub Actions, highlighting the benefits and steps involved in making this transition. The first post sets the context, while subsequent blog posts will dive deeper into the details of using GitHub Actions and nuances to consider while migrating.

Why Consider Migrating to GitHub Actions?

1. Seamless GitHub Integration: GitHub Actions is built directly into GitHub, making it easy to manage workflows without needing external tools.
2. Simplified Configuration: Workflows are defined using YAML files, which are straightforward to read, write, and maintain.
3. Scalability and Flexibility: GitHub Actions supports both cloud-hosted and self-hosted runners, providing flexibility in scaling your CI/CD processes.
4. Cost Efficiency: GitHub Actions can be more cost-effective, especially for open-source projects, offering generous free tiers.

Steps to Migrate from Jenkins to GitHub Actions

1. Audit Your Existing Jenkins Pipelines: Begin by reviewing your current Jenkins pipelines. Identify the stages, tasks, and dependencies involved in your workflows. This audit will help you map out an equivalent workflow in GitHub Actions.
2. Set Up GitHub Actions: Navigate to your GitHub repository and create a new workflow. GitHub offers various templates that can serve as starting points, making it easier to get started.
3. Define Your Workflow: Use a YAML file to outline your workflow. This involves specifying triggers (e.g., push, pull request), jobs, and steps. Each job can run on different runners, and steps can include tasks such as code checkout, testing, and deployment.
4. Translate Build Steps: Convert each step from your Jenkins pipeline into equivalent steps in GitHub Actions. This may involve using specific actions from the GitHub Actions marketplace or writing custom commands.
5. Set Up Runners: Create GitHub runners, which can be set up as a virtual machine (VM) or on Kubernetes. We created a GitHub Actions controller and a set of customized runner scale set listeners. These listeners spin up a Kubernetes pod whenever a GitHub Actions workflow is triggered, and the pod goes down once the workflow steps are complete. This flexibility allows you to scale your CI/CD processes efficiently.
6. Test and Validate: Execute your new GitHub Actions workflow to ensure it performs as expected. Carefully review any errors or issues and refine your workflow until it meets your requirements.
7. Optimize and Enhance: Leverage advanced GitHub Actions features such as matrix builds, reusable workflows, and secrets management to optimize your CI/CD process. Integrate with other GitHub services like Dependabot for automated dependency updates.

Key Considerations

• Security: Ensure that secrets and sensitive information are managed securely using GitHub's secrets management capabilities.
• Compatibility: Verify that all dependencies and tools used in your Jenkins pipeline are compatible with GitHub Actions.
• Documentation: Update your documentation to reflect the new CI/CD process, making it easier for your team to adopt and maintain the new workflows.

Conclusion

Migrating from Jenkins to GitHub Actions can significantly enhance your CI/CD workflows by leveraging GitHub's native capabilities and integrations. By following a structured approach, you can ensure a smooth transition and take full advantage of the features offered by GitHub Actions. This journey not only modernises your development processes but also sets the stage for further enhancements and optimisations.

This blog is the first part of a series documenting our journey to migrate from Jenkins to GitHub Actions. In the upcoming blogs, we will delve into setting up a customised GitHub Actions runner in a Kubernetes cluster, enabling even greater flexibility and scalability for our CI/CD pipelines. Finally, we will define a centralised workflow to use with our customised runners, streamlining the CI/CD process across multiple projects. Stay tuned!

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