Introduction

GitHub Actions has become the go-to CI/CD solution for modern development teams. At Dr. Dangs Lab, we've built pipelines that automatically test, build, and deploy across multiple environments. This guide covers everything from basics to advanced patterns.

Workflow Basics

Anatomy of a Workflow

.github/workflows/ci.yml
name: CI Pipeline
Triggers
on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]
  schedule:
    - cron: '0 0   *'  # Daily at midnight
  workflow_dispatch:  # Manual trigger
Environment variables (workflow-level)
env:
  NODE_VERSION: '20'
  PYTHON_VERSION: '3.11'
Jobs
jobs:
  test:
    name: Run Tests
    runs-on: ubuntu-latest
    # Job-level env vars
    env:
      DATABASE_URL: postgresql://localhost/test
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: ${{ env.NODE_VERSION }}
          cache: 'npm'
      - name: Install dependencies
        run: npm ci
      - name: Run tests
        run: npm test

Trigger Events

on:
  # Push to specific branches
  push:
    branches:
      - main
      - 'release/'
    paths:
      - 'src/'
      - 'package.json'
    paths-ignore:
      - '.md'
      - 'docs/'
  # Pull request events
  pull_request:
    types: [opened, synchronize, reopened]
    branches: [main]
  # Manual trigger with inputs
  workflow_dispatch:
    inputs:
      environment:
        description: 'Deployment environment'
        required: true
        default: 'staging'
        type: choice
        options:
          - staging
          - production
  # Triggered by other workflows
  workflow_call:
    inputs:
      config-file:
        required: true
        type: string
    secrets:
      token:
        required: true

Complete CI Pipeline

Testing and Linting

name: CI
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
jobs:
  lint:
    name: Lint Code
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - name: Install dependencies
        run: npm ci
      - name: Run ESLint
        run: npm run lint
      - name: Run Prettier check
        run: npm run format:check
  type-check:
    name: Type Check
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - run: npm run type-check
  test:
    name: Unit Tests
    runs-on: ubuntu-latest
    needs: [lint, type-check]  # Run after lint and type-check
    services:
      postgres:
        image: postgres:15
        env:
          POSTGRES_USER: test
          POSTGRES_PASSWORD: test
          POSTGRES_DB: test
        ports:
          - 5432:5432
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5
      redis:
        image: redis:7-alpine
        ports:
          - 6379:6379
    steps:
      - uses: actions/checkout@v4
      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - name: Run tests with coverage
        run: npm run test:coverage
        env:
          DATABASE_URL: postgresql://test:test@localhost:5432/test
          REDIS_URL: redis://localhost:6379
      - name: Upload coverage report
        uses: codecov/codecov-action@v3
        with:
          files: ./coverage/lcov.info
          fail_ci_if_error: true
  e2e:
    name: E2E Tests
    runs-on: ubuntu-latest
    needs: test
    steps:
      - uses: actions/checkout@v4
      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - name: Install Playwright browsers
        run: npx playwright install --with-deps
      - name: Run E2E tests
        run: npm run test:e2e
      - name: Upload test artifacts
        uses: actions/upload-artifact@v4
        if: failure()
        with:
          name: playwright-report
          path: playwright-report/
          retention-days: 7

Docker Build and Push

name: Build and Push Docker
on:
  push:
    branches: [main]
    tags: ['v*']
env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}
jobs:
  build:
    name: Build Docker Image
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
    outputs:
      image-tag: ${{ steps.meta.outputs.tags }}
      image-digest: ${{ steps.build.outputs.digest }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3
      - name: Log in to Container Registry
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=ref,event=branch
            type=ref,event=pr
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=sha,prefix=
      - name: Build and push
        id: build
        uses: docker/build-push-action@v5
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max
          build-args: |
            BUILD_DATE=${{ github.event.head_commit.timestamp }}
            GIT_SHA=${{ github.sha }}
  scan:
    name: Security Scan
    runs-on: ubuntu-latest
    needs: build
    steps:
      - name: Run Trivy vulnerability scanner
        uses: aquasecurity/trivy-action@master
        with:
          image-ref: ${{ needs.build.outputs.image-tag }}
          format: 'sarif'
          output: 'trivy-results.sarif'
      - name: Upload scan results
        uses: github/codeql-action/upload-sarif@v2
        with:
          sarif_file: 'trivy-results.sarif'

Deployment Workflows

Deploy to AWS ECS

name: Deploy to AWS
on:
  workflow_run:
    workflows: ["Build and Push Docker"]
    types: [completed]
    branches: [main]
jobs:
  deploy:
    name: Deploy to ECS
    runs-on: ubuntu-latest
    if: ${{ github.event.workflow_run.conclusion == 'success' }}
    environment:
      name: production
      url: https://api.example.com
    steps:
      - name: Checkout
        uses: actions/checkout@v4
      - name: Configure AWS credentials
        uses: aws-actions/configure-aws-credentials@v4
        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: Download task definition
        run: |
          aws ecs describe-task-definition \
            --task-definition my-app \
            --query taskDefinition > task-definition.json
      - name: Update task definition
        id: task-def
        uses: aws-actions/amazon-ecs-render-task-definition@v1
        with:
          task-definition: task-definition.json
          container-name: api
          image: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }}
      - name: Deploy to ECS
        uses: aws-actions/amazon-ecs-deploy-task-definition@v1
        with:
          task-definition: ${{ steps.task-def.outputs.task-definition }}
          service: my-app-service
          cluster: my-cluster
          wait-for-service-stability: true

Deploy to Vercel

name: Deploy to Vercel
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
jobs:
  deploy:
    name: Deploy
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Install Vercel CLI
        run: npm install -g vercel@latest
      - name: Pull Vercel Environment
        run: vercel pull --yes --environment=production --token=${{ secrets.VERCEL_TOKEN }}
      - name: Build Project
        run: vercel build --prod --token=${{ secrets.VERCEL_TOKEN }}
      - name: Deploy to Vercel
        id: deploy
        run: |
          url=$(vercel deploy --prebuilt --prod --token=${{ secrets.VERCEL_TOKEN }})
          echo "url=$url" >> $GITHUB_OUTPUT
      - name: Comment on PR
        if: github.event_name == 'pull_request'
        uses: actions/github-script@v7
        with:
          script: |
            github.rest.issues.createComment({
              issue_number: context.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: '🚀 Preview deployed: ${{ steps.deploy.outputs.url }}'
            })

Matrix Builds

name: Matrix Build
on: [push, pull_request]
jobs:
  test:
    name: Test on ${{ matrix.os }} with Node ${{ matrix.node }}
    runs-on: ${{ matrix.os }}
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
        node: [18, 20, 22]
        exclude:
          - os: windows-latest
            node: 18
        include:
          - os: ubuntu-latest
            node: 20
            coverage: true
    steps:
      - uses: actions/checkout@v4
      - name: Setup Node.js ${{ matrix.node }}
        uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node }}
          cache: 'npm'
      - run: npm ci
      - run: npm test
      - name: Upload coverage
        if: matrix.coverage
        uses: codecov/codecov-action@v3

Reusable Workflows

Creating a Reusable Workflow

.github/workflows/reusable-deploy.yml
name: Reusable Deploy Workflow
on:
  workflow_call:
    inputs:
      environment:
        required: true
        type: string
      image-tag:
        required: true
        type: string
    secrets:
      AWS_ACCESS_KEY_ID:
        required: true
      AWS_SECRET_ACCESS_KEY:
        required: true
jobs:
  deploy:
    name: Deploy to ${{ inputs.environment }}
    runs-on: ubuntu-latest
    environment: ${{ inputs.environment }}
    steps:
      - uses: actions/checkout@v4
      - name: Configure AWS
        uses: aws-actions/configure-aws-credentials@v4
        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
        run: |
          echo "Deploying ${{ inputs.image-tag }} to ${{ inputs.environment }}"
          # Deployment commands here

Using the Reusable Workflow

.github/workflows/main.yml
name: Main Pipeline
on:
  push:
    branches: [main]
jobs:
  build:
    # ... build job
  deploy-staging:
    needs: build
    uses: ./.github/workflows/reusable-deploy.yml
    with:
      environment: staging
      image-tag: ${{ needs.build.outputs.image-tag }}
    secrets:
      AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
      AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
  deploy-production:
    needs: [build, deploy-staging]
    uses: ./.github/workflows/reusable-deploy.yml
    with:
      environment: production
      image-tag: ${{ needs.build.outputs.image-tag }}
    secrets:
      AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
      AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}

Secrets and Environment Management

jobs:
  deploy:
    runs-on: ubuntu-latest
    environment:
      name: production
      url: https://example.com
    steps:
      # Access secrets
      - name: Use secrets
        env:
          API_KEY: ${{ secrets.API_KEY }}
          DATABASE_URL: ${{ secrets.DATABASE_URL }}
        run: |
          echo "Deploying with configured secrets"
      # Mask sensitive output
      - name: Generate token
        id: token
        run: |
          TOKEN=$(generate-token)
          echo "::add-mask::$TOKEN"
          echo "token=$TOKEN" >> $GITHUB_OUTPUT

Advanced Patterns

Conditional Jobs

jobs:
  check-changes:
    runs-on: ubuntu-latest
    outputs:
      frontend: ${{ steps.filter.outputs.frontend }}
      backend: ${{ steps.filter.outputs.backend }}
    steps:
      - uses: actions/checkout@v4
      - uses: dorny/paths-filter@v2
        id: filter
        with:
          filters: |
            frontend:
              - 'frontend/'
            backend:
              - 'backend/'
  build-frontend:
    needs: check-changes
    if: needs.check-changes.outputs.frontend == 'true'
    runs-on: ubuntu-latest
    steps:
      - run: echo "Building frontend"
  build-backend:
    needs: check-changes
    if: needs.check-changes.outputs.backend == 'true'
    runs-on: ubuntu-latest
    steps:
      - run: echo "Building backend"

Caching Dependencies

steps:
  - uses: actions/checkout@v4
  # npm cache
  - uses: actions/setup-node@v4
    with:
      node-version: '20'
      cache: 'npm'
  # Custom cache
  - name: Cache Playwright browsers
    uses: actions/cache@v4
    id: playwright-cache
    with:
      path: ~/.cache/ms-playwright
      key: playwright-${{ runner.os }}-${{ hashFiles('package-lock.json') }}
  - name: Install Playwright
    if: steps.playwright-cache.outputs.cache-hit != 'true'
    run: npx playwright install --with-deps

Notification on Failure

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      # ... build steps
  notify:
    needs: build
    if: failure()
    runs-on: ubuntu-latest
    steps:
      - name: Notify Slack
        uses: 8398a7/action-slack@v3
        with:
          status: failure
          channel: '#deployments'
          fields: repo,commit,author,action,workflow
        env:
          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK }}

Key Takeaways

1. Start simple - Add complexity as needed 2. Use caching - Speed up builds significantly 3. Leverage matrix builds - Test across environments 4. Create reusable workflows - DRY principle 5. Secure secrets - Use environments and OIDC 6. Monitor and alert - Know when things break 7. Optimize for speed - Parallel jobs, caching

Conclusion

GitHub Actions provides a powerful, flexible CI/CD platform integrated directly into your repository. Start with basic workflows, then gradually adopt advanced patterns like reusable workflows and matrix builds. The key is to automate everything that can be automated.

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