What is Docker Compose and what is it good for?

Compose describes services, networks, volumes and configuration. It creates a default network so services resolve each other by name, and it can build images as well as pull them. It is not a cluster orchestrator, but it is a reliable way to run an application stack on one machine.

services:
  api:
    build: .
    ports:
      - "8080:3000"
    environment:
      DATABASE_URL: postgres://app:secret@db:5432/app
    depends_on:
      db:
        condition: service_healthy
  db:
    image: postgres:16
    volumes:
      - pgdata:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U app"]
      interval: 5s
      retries: 10
volumes:
  pgdata:

Where it fits

• Local development with a database, cache and queue
• Integration tests that need real dependencies
• Single-host deployments for small internal services
• A readable description of how services relate

depends_on with a health condition controls startup order, but it does not make an application resilient. Services should still retry connections and handle a dependency that restarts. For multi-node scheduling, rolling updates and self-healing, use an orchestrator.