CI/CD (Continuous Integration / Continuous Deployment)
A set of practices that enable development teams to deliver code changes more frequently and reliably.
Detailed Explanation
Continuous Integration (CI) involves automatically building and testing code every time a developer pushes a change. Continuous Deployment (CD) goes a step further by automatically deploying those changes to production after they pass the tests. This pipeline reduces manual errors, speeds up the feedback loop, and ensures that software is always in a deployable state.
Quick Summary
CI/CD automates the path from a developer's commit to running production code. CI builds and tests every change; CD ships the artifact to staging (continuous delivery) or all the way to prod (continuous deployment).
Key Takeaways
- CI proves that every change still builds, tests, and integrates cleanly, typically per pull request.
- Continuous Delivery means every passing build is releasable; Continuous Deployment means every passing build is actually released, automatically.
- Fast pipelines (<10 min) keep developers in flow; slow pipelines (>30 min) cause batching, which defeats the purpose.
- Pipelines should produce an immutable artifact (binary, container image) and promote that same artifact across environments, no per-env builds.
- Common tools: GitHub Actions, GitLab CI, CircleCI, Buildkite, Jenkins; cloud-managed runners are the default for new projects.
When to use it
- Per-PR checks: lint, type-check, unit tests, security scans, preview deploys.
- Trunk-based development where mainline is always green and shippable.
- Multi-stage deploys: dev → staging → production, with promotion gates between.
- Release automation: signing artifacts, publishing to npm/PyPI, and updating changelogs.
Common Mistakes
- Flaky tests that pass locally but fail in CI, eroding trust until people merge with red builds.
- Building the artifact separately in each environment instead of promoting a single build through them.
- Sprawling YAML configs with copy-pasted steps; refactor into reusable workflows or composite actions.
- Skipping rollback automation, so a bad deploy needs manual intervention to recover.
CI/CD (Continuous Integration / Continuous Deployment), Frequently Asked
Continuous Delivery vs. Continuous Deployment?
Continuous Delivery means every change is automatically built, tested, and made ready to ship; a human pushes the button. Continuous Deployment removes the human and ships every passing build to production automatically.
How fast should my CI pipeline be?
Under 10 minutes for the per-PR feedback path. Above that, developers context-switch, batch changes, and lose the safety net CI is supposed to provide. Cache dependencies, parallelize tests, and split slow integration tests into nightly jobs.
Do I need staging if I have feature flags?
Often less of one. Feature flags let you deploy code dark and enable it gradually, reducing the need for a long-lived staging clone. Most teams keep a thin staging environment for integration smoke tests but make production the real test environment.