12. Git in CI/CD — Automation & Deployment

⚙️ What CI/CD Actually Does

🐙 GitHub Actions — CI/CD Built Into GitHub

GitHub Actions is GitHub's built-in CI/CD system. It runs automated workflows in response to Git events (push, pull request, merge). Workflows are defined in YAML files in .github/workflows/:

The workflow YAML file lives at .github/workflows/ci.yml. A basic CI pipeline in YAML would:

1. Trigger on every push and pull request
2. Check out the code
3. Set up Node.js
4. Install dependencies (npm install)
5. Run tests (npm test)
6. Run linting (npm run lint)
7. Build the app (npm run build)

If any step fails, the PR cannot be merged (due to branch protection rules).

🔒 Branch Protection Rules

Branch protection rules on GitHub prevent developers from pushing directly to main or force-pushing over history. Configure these in: GitHub repo → Settings → Branches → Add rule. Required settings for a professional team:

• Require pull request before merging — No direct pushes to main
• Require at least 1 approval — Another developer must review before merge
• Require status checks to pass — CI pipeline must pass (tests green)
• Require branches to be up to date — Branch must include latest main before merge
• Do not allow force pushes — History is permanent; cannot be rewritten

🏷️ Git Tags & Releases

Tags mark specific commits as important (usually version releases). Create a lightweight tag:

Create an annotated tag (with a message and tagger info):

Push tags to remote (they don't push automatically with git push):

List all tags:

Checkout a specific version to inspect it:

On GitHub, tags automatically create a Release page where you can attach release notes and downloadable build artefacts.