compose

Docker Compose Configuration Skill

Overview

This skill generates Docker Compose configurations for multi-container applications. It creates properly structured compose files with:

• Service definitions
• Network configuration
• Volume management
• Health checks
• Dependencies
• Environment configuration

Activation

Use this skill when:

• Creating a new compose file
• Adding services to existing compose
• Configuring container orchestration
• Setting up development or production environments

Process

1. Understand Requirements

Gather information about:

• Required services (web, api, database, cache, etc.)
• Environment (development/production)
• Networking needs (internal, external, SSL)
• Persistence requirements
• Scaling needs

2. Consult Documentation

Read relevant documentation:

• 03-compose-fundamentals.md for structure
• 04-networking.md for networks
• 05-databases.md for database services
• 06-services.md for dependencies
• 08-volumes.md for persistence

3. Generate Configuration

Create compose file following best practices:

# Modern compose (no version field)
services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    restart: unless-stopped
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=production
    depends_on:
      db:
        condition: service_healthy
    networks:
      - frontend
      - backend
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:3000/health"]
      interval: 30s
      timeout: 10s
      retries: 3

  db:
    image: postgres:16-alpine
    restart: unless-stopped
    environment:
      POSTGRES_USER: ${DB_USER}
      POSTGRES_PASSWORD: ${DB_PASSWORD}
      POSTGRES_DB: ${DB_NAME}
    volumes:
      - postgres_data:/var/lib/postgresql/data
    networks:
      - backend
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${DB_USER}"]
      interval: 10s
      timeout: 5s
      retries: 5

volumes:
  postgres_data:

networks:
  frontend:
  backend:
    internal: true

Service Patterns

Web Application

services:
  web:
    build: .
    ports:
      - "80:80"
    depends_on:
      - api

API Service

services:
  api:
    build: ./api
    expose:
      - "3000"
    environment:
      - DATABASE_URL=postgresql://user:pass@db:5432/app
    depends_on:
      db:
        condition: service_healthy

Database Service

services:
  db:
    image: postgres:16-alpine
    volumes:
      - db_data:/var/lib/postgresql/data
    environment:
      POSTGRES_PASSWORD: ${DB_PASSWORD}
    healthcheck:
      test: ["CMD-SHELL", "pg_isready"]
      interval: 10s
      retries: 5

Cache Service

services:
  redis:
    image: redis:7-alpine
    command: redis-server --appendonly yes
    volumes:
      - redis_data:/data

Background Worker

services:
  worker:
    build: .
    command: npm run worker
    depends_on:
      - db
      - redis

Network Patterns

Internal Database Network

networks:
  backend:
    internal: true  # No external access

External Shared Network

networks:
  proxy:
    external: true
    name: traefik_proxy

Volume Patterns

Named Volume

volumes:
  postgres_data:

Bind Mount (Development)

volumes:
  - ./src:/app/src

Anonymous Volume

volumes:
  - /app/node_modules

Environment Patterns

Direct Values

environment:
  - NODE_ENV=production

From .env File

env_file:
  - .env

With Defaults

environment:
  - DB_HOST=${DB_HOST:-localhost}

Output

Generated compose file includes:

• All required services
• Proper network configuration
• Volume definitions
• Health checks
• Dependency management
• Environment configuration
• Comments for complex settings