CI/CD

In simple terms

CI/CD stands for Continuous Integration and Continuous Delivery (or Deployment). It’s the practice — and the toolchain — that runs your tests on every commit and automatically packages and ships the code if those tests pass. The goal is to make releases boring: small, frequent, and reversible.

More detail

Continuous Integration (CI) focuses on the path from commit to merged:

• Every push triggers a pipeline: install dependencies, lint, type-check, build, run tests, scan for vulnerabilities.
• Branches merge to main only when the pipeline is green.
• Failures are loud and quick to fix while the change is small.

Continuous Delivery extends the pipeline: any green main is deployable on demand. Continuous Deployment removes even the manual click: every green main goes to production automatically.

A typical pipeline:

push → lint → build → unit tests → integration tests → security scan
     → docker image → deploy to staging → smoke tests → manual approval?
     → canary deploy to production → full rollout

Mainstream platforms:

• GitHub Actions, GitLab CI/CD, Bitbucket Pipelines (Git-host-native).
• Buildkite, CircleCI, Jenkins (standalone).
• Argo CD, Flux (GitOps-style continuous deployment to Kubernetes).

Healthy pipelines:

• Run in < 10 minutes for most repos (faster is better).
• Cache aggressively (dependencies, builds, Docker layers).
• Are deterministic: same commit, same result.
• Run on every commit, not just main.

Why it matters

CI/CD turns “release day” into “every day”. It catches bugs while the diff is small, makes rollback a one-command operation, and lets a team ship many times per day with confidence. The Accelerate / DORA research links high deploy frequency directly to organisational performance.

Real-world examples

• A typical PR opens, runs ~3 minutes of CI, gets reviewed, gets merged, and is in production within an hour.

• Large companies (Amazon, Google) deploy thousands of times per day across their services.

• A canary deploy shifts 5% of traffic to the new version first; if metrics stay healthy, it rolls forward.

• Spotify deploys to production thousands of times a day; their entire pipeline (build, test, canary, full rollout) is measured in minutes, not hours.

Common misconceptions

• “CI = running tests.” Tests are the core; lint, build, security scan, and packaging are part of it too.
• “Continuous deployment is reckless.” Done with good tests, canary deploys, and observability, it is less risky than infrequent big-bang releases.

Learn next

The release end of the pipe: deployment. The discipline that fills the pipe: testing.