CI/CD Pipelines: A Practical Introduction Without the Buzzword Overload

Continuous Integration (CI) is the practice of frequently merging code changes into a shared branch and automatically running tests to catch integration issues early. The goal is finding conflicts and bugs before they accumulate. Continuous Delivery (CD) extends CI by automatically building deployable artifacts and potentially deploying them to staging environments — but the final production push requires manual approval. Continuous Deployment goes one step further: every change that passes all automated checks is automatically deployed to production with no manual step. Most teams practice CI and Continuous Delivery; full Continuous Deployment is appropriate when you have high test coverage, good rollback mechanisms, and incremental change processes like feature flags.

A basic CI pipeline should: install dependencies, run a linter (catches style and common errors instantly), run type checking if using TypeScript, run unit tests, run integration tests if they exist, build the project (ensuring the build isn't broken), and report success or failure back to the PR. Optionally: run security dependency audits (npm audit, Snyk), check code coverage and fail below a threshold, run end-to-end tests against a test environment, and run performance benchmarks. The pipeline should fail fast — put quick, cheap checks (linting, type checking) first so slow checks (E2E tests) only run on code that passed the basics. A pipeline that takes 20 minutes destroys developer feedback loops.

GitHub Actions is now the default for projects hosted on GitHub — free for public repos, tightly integrated with GitHub PRs and security. GitLab CI is built into GitLab with a similar feature set and stronger support for self-hosted environments. Jenkins is the most flexible and powerful but requires significant infrastructure setup and maintenance — better for enterprises with complex requirements. CircleCI and Buildkite are hosted services offering performance and parallelization features for larger teams. For most projects on GitHub, GitHub Actions is the easiest starting point. For enterprise environments with specific security or compliance requirements, self-hosted options with Jenkins or GitLab are common. The YAML syntax differs but the concepts are identical across all platforms.