CI/CD with GitHub Actions: A Practical Intro

CI/CD is the practice of running your tests and deploys automatically on every push. GitHub Actions makes it a single YAML file in your repo. Once it's green, you can merge with confidence.

Your first workflow

# .github/workflows/ci.yml
name: CI
on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"
      - run: pip install -r requirements.txt
      - run: pytest -q
      - run: ruff check .

Cache dependencies

      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"
          cache: pip
      - run: pip install -r requirements.txt

The cache: pip line caches your packages between runs, cutting minutes off every build.

Deploy on merge

  deploy:
    needs: test          # only runs if tests pass
    runs-on: ubuntu-latest
    if: github.ref == 'refs/heads/main'
    steps:
      - uses: actions/checkout@v4
      - name: Deploy
        env:
          RENDER_DEPLOY_HOOK: ${{ secrets.RENDER_DEPLOY_HOOK }}
        run: curl -s "$RENDER_DEPLOY_HOOK"

Secrets — never in code

Store tokens in Settings → Secrets and variables → Actions, and reference them as ${{ secrets.NAME }}. They're injected only at runtime and never printed in logs.

What to run

• Tests, on every push.
• A linter and formatter check.
• A type check (mypy / tsc).
• A build step that proves the app compiles.
• A deploy, gated on main.

Keep CI fast — under a few minutes. A slow pipeline is a pipeline people start ignoring.

CI is the cheapest insurance you can buy. The first time it catches a bug you'd have shipped, it pays for itself.