compose-setup

DevOps & Security

Generate docker-compose.yml for multi-service setups including databases, caches, and service dependencies. Use when the app needs a database, cache, message broker, or has multiple independently deployable services.

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Docker Compose Setup

Generate docker-compose.yml when the application needs multiple services (app + database, app + cache, monorepo services).

When to use docker-compose

App requires a database (PostgreSQL, MySQL, MongoDB, Redis)
App has multiple independently deployable services
App needs a message broker (RabbitMQ, Kafka)
Monorepo with multiple Dockerfile entries

Single-service apps with no external dependencies should use a standalone Dockerfile.

Detection from source code

Look for these signals to determine required services:

Pattern in code or config	Service needed
`DATABASE_URL=postgres://` or `pg` dependency	PostgreSQL
`DATABASE_URL=mysql://` or `mysql2` dependency	MySQL
`MONGODB_URI` or `mongoose` dependency	MongoDB
`REDIS_URL` or `ioredis`/`redis` dependency	Redis
`RABBITMQ_URL` or `amqplib` dependency	RabbitMQ
`KAFKA_BROKERS`	Kafka
`.env.example` listing service URLs	Parse each URL for service type

Compose template structure

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "${PORT:-3000}:3000"
    environment:
      - NODE_ENV=production
      - DATABASE_URL=postgresql://postgres:postgres@db:5432/app
    depends_on:
      db:
        condition: service_healthy
    restart: unless-stopped

  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: app
    volumes:
      - pgdata:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U postgres"]
      interval: 5s
      timeout: 3s
      retries: 5
    restart: unless-stopped

volumes:
  pgdata:

Common service blocks

PostgreSQL

db:
  image: postgres:16-alpine
  environment:
    POSTGRES_USER: postgres
    POSTGRES_PASSWORD: postgres
    POSTGRES_DB: app
  volumes:
    - pgdata:/var/lib/postgresql/data
  healthcheck:
    test: ["CMD-SHELL", "pg_isready -U postgres"]
    interval: 5s
    timeout: 3s
    retries: 5

MySQL

db:
  image: mysql:8.0
  environment:
    MYSQL_ROOT_PASSWORD: root
    MYSQL_DATABASE: app
    MYSQL_USER: app
    MYSQL_PASSWORD: app
  volumes:
    - mysqldata:/var/lib/mysql
  healthcheck:
    test: ["CMD", "mysqladmin", "ping", "-h", "localhost"]
    interval: 5s
    timeout: 3s
    retries: 5

MongoDB

mongo:
  image: mongo:7
  environment:
    MONGO_INITDB_ROOT_USERNAME: root
    MONGO_INITDB_ROOT_PASSWORD: root
  volumes:
    - mongodata:/data/db
  healthcheck:
    test: ["CMD", "mongosh", "--eval", "db.adminCommand('ping')"]
    interval: 5s
    timeout: 3s
    retries: 5

Redis

redis:
  image: redis:7-alpine
  command: redis-server --appendonly yes
  volumes:
    - redisdata:/data
  healthcheck:
    test: ["CMD", "redis-cli", "ping"]
    interval: 5s
    timeout: 3s
    retries: 5

Monorepo services

For monorepos with multiple services under apps/ or services/:

services:
  api:
    build:
      context: .
      dockerfile: apps/api/Dockerfile
    ports:
      - "3001:3001"
    depends_on:
      db:
        condition: service_healthy

  web:
    build:
      context: .
      dockerfile: apps/web/Dockerfile
    ports:
      - "3000:3000"
    depends_on:
      - api

Set build context to the repo root so shared packages are accessible. Each Dockerfile handles its own COPY paths.

Rules

Always use named volumes for persistent data
Always add healthchecks for databases and caches
Use depends_on with condition: service_healthy so the app waits for healthy dependencies
Use restart: unless-stopped for all services
Reference env vars from .env.example when available
Default to Alpine/slim images for smaller footprint
Pin image versions (e.g. postgres:16-alpine, not postgres:latest)

Related Skills

env-detection — Detect required service connection URLs (DATABASE_URL, REDIS_URL, etc.) to determine which services to include
dockerfile-generation — Generate the Dockerfile for each service in the compose file