Docker CI/CD

Integrating Docker with a CI/CD pipeline to automate build, test, and deployment.

GitHub Actions

# .github/workflows/docker.yml
name: Docker CI/CD

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

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Build image
        run: docker build -t myapp:${{ github.sha }} .

      - name: Run tests
        run: docker run myapp:${{ github.sha }} npm test

  deploy:
    needs: build
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Login to Docker Hub
        uses: docker/login-action@v2
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_TOKEN }}

      - name: Build and push
        uses: docker/build-push-action@v4
        with:
          push: true
          tags: username/myapp:${{ github.sha }}

GitLab CI

# .gitlab-ci.yml
stages:
  - build
  - test
  - deploy

build:
  stage: build
  script:
    - docker build -t myapp:$CI_COMMIT_SHA .

test:
  stage: test
  script:
    - docker run myapp:$CI_COMMIT_SHA npm test

deploy:
  stage: deploy
  only:
    - main
  script:
    - docker tag myapp:$CI_COMMIT_SHA username/myapp:latest
    - docker push username/myapp:latest

Use Case: Application CI/CD

# .github/workflows/myapp.yml
name: MyApp CI/CD

on:
  push:
    branches: [main, develop]

jobs:
  test:
    runs-on: ubuntu-latest
    services:
      postgres:
        image: postgres:15
        env:
          POSTGRES_DB: test_db
          POSTGRES_USER: test
          POSTGRES_PASSWORD: test
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5
        ports:
          - 5432:5432

    steps:
      - uses: actions/checkout@v3

      - name: Build and test
        run: |
          docker build -t myapp-api:test .
          docker run --network host myapp-api:test npm test

  deploy:
    needs: test
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Deploy to production
        run: |
          docker build -t myapp-api:latest .
          docker push username/myapp-api:latest
          # Deploy to the server

Everyday Use Case

Case: A developer pushes code, and it is deployed automatically.

# Push to GitHub
git push origin main

# GitHub Actions will:
# 1. Build the image
# 2. Run the tests
# 3. Push to Docker Hub
# 4. Deploy to the server

Best Practices

1. Use multi-stage builds: For smaller images
2. Cache dependencies: For faster builds
3. Run tests in a container: For consistency
4. Use secrets: For credentials
5. Rollback strategy: Prepare a way to roll back if a deployment fails

Conclusion

CI/CD with Docker automates the deployment process. For applications, use GitHub Actions or GitLab CI for automation.