A Simple Analogy

GitHub Actions is like hiring robots to run your tests and deploy your code. Every time you push, robots automatically test, build, and deploy—no manual work needed.

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Why GitHub Actions?

• Automation: No manual testing/deployment
• Integrated: Runs right in GitHub
• Flexible: Write custom workflows
• Free tier: Generous free minutes
• Notifications: Slack, email alerts

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Basic Workflow

# .github/workflows/ci.yml
name: CI

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

jobs:
  test:
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Setup Node.js
      uses: actions/setup-node@v3
      with:
        node-version: '18'
    
    - name: Install dependencies
      run: npm ci
    
    - name: Run tests
      run: npm test
    
    - name: Run linter
      run: npm run lint

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.NET Workflow

name: .NET CI

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

jobs:
  build:
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Setup .NET
      uses: actions/setup-dotnet@v3
      with:
        dotnet-version: '8.0.x'
    
    - name: Restore dependencies
      run: dotnet restore
    
    - name: Build
      run: dotnet build --configuration Release
    
    - name: Test
      run: dotnet test --configuration Release --no-build
    
    - name: Publish
      run: dotnet publish -c Release -o release

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Deployment Workflow

name: Deploy

on:
  push:
    branches: [ main ]

jobs:
  deploy:
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Build Docker image
      run: docker build -t myapp:${{ github.sha }} .
    
    - name: Push to registry
      run: |
        echo ${{ secrets.DOCKER_PASSWORD }} | docker login -u ${{ secrets.DOCKER_USERNAME }} --password-stdin
        docker push myapp:${{ github.sha }}
    
    - name: Deploy to server
      uses: appleboy/ssh-action@master
      with:
        host: ${{ secrets.HOST }}
        username: ${{ secrets.USER }}
        key: ${{ secrets.SSH_KEY }}
        script: |
          docker pull myapp:${{ github.sha }}
          docker run -d -p 80:3000 myapp:${{ github.sha }}

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Matrix Testing

name: Test Multiple Versions

on: [push]

jobs:
  test:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        node-version: [16.x, 18.x, 20.x]
        os: [ubuntu-latest, windows-latest]
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Use Node.js ${{ matrix.node-version }}
      uses: actions/setup-node@v3
      with:
        node-version: ${{ matrix.node-version }}
    
    - run: npm ci
    - run: npm test

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Secrets Management

name: Secure Deployment

on:
  push:
    branches: [ main ]

jobs:
  deploy:
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Configure AWS credentials
      uses: aws-actions/configure-aws-credentials@v2
      with:
        aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
        aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
        aws-region: us-east-1
    
    - name: Deploy to AWS
      run: |
        aws s3 cp . s3://my-bucket --recursive
        aws cloudfront create-invalidation --distribution-id ${{ secrets.DISTRIBUTION_ID }} --paths "/*"

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Best Practices

1. Keep workflows simple: One job per responsibility
2. Use actions from marketplace: Don't reinvent
3. Cache dependencies: Speed up builds
4. Manage secrets securely: Never hardcode
5. Notify on failure: Get alerts quickly

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Related Concepts

• GitLab CI/CD
• Jenkins
• CircleCI
• Artifact storage

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Summary

GitHub Actions automates testing and deployment directly from your repository. Define workflows in YAML to build, test, and deploy with every push.