GitLab CI vs Github Actions: What are the differences?

Introduction: GitLab CI and GitHub Actions are both continuous integration and continuous delivery (CI/CD) platforms that help automate software development workflows. While they serve a similar purpose, they have several key differences that make each platform unique.

1. Workflow Configuration: GitLab CI uses a YAML file called .gitlab-ci.yml to define the stages, jobs, and steps of a CI/CD pipeline. It follows a declarative approach, allowing users to specify the desired state of the pipeline. On the other hand, GitHub Actions uses YAML files called workflow files that are stored in the .github/workflows directory. It follows an imperative approach, allowing users to define the exact steps to be executed.

2. Built-in Integration: GitLab CI is tightly integrated with the GitLab platform, providing seamless integration with other GitLab features like issue tracking, code reviews, and container registry. GitHub Actions, on the other hand, is closely integrated with GitHub, offering native integration with pull requests, issues, and the GitHub ecosystem.

3. Parallel Execution: GitLab CI allows parallel execution of jobs by default, enabling faster CI/CD pipelines. It automatically distributes jobs across available runners, optimizing resource utilization. In contrast, GitHub Actions had a limited parallelism feature initially, but now also allows parallel execution, albeit with some limitations on the number of concurrent jobs depending on the user plan.

4. Pricing Model: GitLab CI is part of the GitLab platform, which comes with a different pricing structure based on GitLab's plans. It offers various tiers ranging from free to enterprise editions, with different features and capabilities. GitHub Actions, on the other hand, is included in all GitHub plans, including the free tier, allowing users to benefit from its CI/CD capabilities at no additional cost.

5. Third-Party Actions: GitHub Actions has a rich ecosystem of third-party actions available in the GitHub Marketplace. These pre-built actions provide additional functionality and integrations that can be easily added to workflows. GitLab CI also has a collection of community-contributed CI/CD templates, but the availability of pre-built actions is not as extensive as in GitHub Actions.

6. Deployment Environments: GitLab CI allows the definition of multiple deployment environments, each representing a stage in the software delivery pipeline. It facilitates the separation of tasks and enables easy promotion of code through different environments. GitHub Actions, on the other hand, does not have a built-in feature similar to GitLab's deployment environments, making it less suitable for complex multi-stage deployment scenarios.

In summary, GitLab CI and GitHub Actions differ in their workflow configuration, integration with the respective platforms, parallel execution capabilities, pricing models, availability of third-party actions, and support for deployment environments. The choice between the two depends on the specific requirements of the project and the development team's preferences.