Introduction to GitHub Actions

GitHub Actions is the built-in CI/CD and automation platform for GitHub repositories. With a YAML file in your repository, you can automatically run tests on every pull request, build and push Docker images on merge, deploy to production on a tag, or run any script on a schedule.

Key Concepts

Your First Workflow — CI for a Node.js Project

name: CI

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  test:
    runs-on: ubuntu-latest

    steps:
      - name: Check out code
        uses: actions/checkout@v4

      - name: Set up Node.js
        uses: actions/setup-node@v4
        with:
          node-version: "20"
          cache: "npm"

      - name: Install dependencies
        run: npm ci

      - name: Run linter
        run: npm run lint

      - name: Run tests
        run: npm test

Save this as .github/workflows/ci.yml. Every push to main or PR targeting main will now automatically run your lint and test suite.

Triggers (on:)

# Run on push to main or any release/* branch
on:
  push:
    branches: [main, "release/*"]

# Run on any PR targeting main
on:
  pull_request:
    branches: [main]

# Run every day at 06:00 UTC
on:
  schedule:
    - cron: "0 6 * * *"

# Allow manual trigger from the GitHub UI
on:
  workflow_dispatch:
    inputs:
      environment:
        description: "Target environment"
        required: true
        default: "staging"

Secrets and Environment Variables

Store sensitive values in GitHub repository secrets (Settings → Secrets and variables → Actions). Access them in workflows via the secrets context:

      - name: Deploy to production
        env:
          API_KEY: ${{ secrets.DEPLOY_API_KEY }}
        run: ./scripts/deploy.sh

Secrets are masked in logs — GitHub replaces them with ***. Never print secrets with echo or store them in environment variables that get logged.

Job Dependencies

By default jobs run in parallel. Use needs to create a dependency chain:

jobs:
  test:
    runs-on: ubuntu-latest
    steps: [...]

  build:
    needs: test
    runs-on: ubuntu-latest
    steps: [...]

  deploy:
    needs: build
    runs-on: ubuntu-latest
    steps: [...]

Popular Actions from the Marketplace

GitHub Actions is covered in more depth in the DevOps and SRE Fundamentals course — this lesson gives you the foundation to understand CI/CD pipelines in a GitHub context.