YAML

# Strings
name: Alice
quoted: "Hello, World!"
multiline: |
  Line one
  Line two
folded: >
  This is a long line that
  gets folded into one.

# Numbers & booleans
age: 30
price: 9.99
enabled: true
disabled: false
not_set: null

# Lists
fruits:
  - apple
  - banana
  - cherry
inline: [1, 2, 3]

# Maps
address:
  street: 123 Main St
  city: Springfield
inline_map: {a: 1, b: 2}

# Define anchor
defaults: &defaults
  timeout: 30
  retries: 3
  log_level: info

# Reuse with alias
production:
  <<: *defaults      # Merge defaults
  log_level: warn    # Override one field
  replicas: 5

staging:
  <<: *defaults
  replicas: 1

# Multiple environment example
x-common: &common
  image: my-app:latest
  restart: unless-stopped

services:
  web:
    <<: *common
    ports: ['80:8080']
  worker:
    <<: *common
    command: worker

services:
  app:
    build: .
    ports:
      - "3000:3000"
    environment:
      DATABASE_URL: postgres://db:5432/app
      REDIS_URL: redis://cache:6379
    depends_on:
      db:
        condition: service_healthy
    volumes:
      - ./src:/app/src        # Dev hot-reload

  db:
    image: postgres:16-alpine
    volumes:
      - pgdata:/var/lib/postgresql/data
    environment:
      POSTGRES_DB: app
      POSTGRES_PASSWORD: secret
    healthcheck:
      test: ["CMD", "pg_isready", "-U", "postgres"]
      interval: 5s
      retries: 5

  cache:
    image: redis:7-alpine

volumes:
  pgdata:

name: CI/CD

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

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'          # Caches node_modules

      - run: npm ci
      - run: npm test

  deploy:
    needs: test              # Only runs if test passes
    runs-on: ubuntu-latest
    if: github.ref == 'refs/heads/main'
    environment: production
    steps:
      - uses: actions/checkout@v4
      - run: ./deploy.sh
        env:
          API_KEY: ${{ secrets.API_KEY }}