Docker Compose¶

Compose describes a local multi-service application as configuration: services, networks, volumes, environment, ports, health checks, dependencies, and restart behavior. It replaces brittle sequences of manual docker run commands.

Use docker compose up, down, ps, logs, exec, build, and pull as lifecycle commands. depends_on controls startup ordering, not application readiness; use health checks and retry logic where one service truly requires another to be ready.

Small local stack¶

services:
  api:
    build: .
    ports: ["8000:8000"]
    depends_on:
      db:
        condition: service_healthy
  db:
    image: postgres:16
    environment:
      POSTGRES_PASSWORD: change-me
    volumes: ["db-data:/var/lib/postgresql/data"]
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U postgres"]
volumes:
  db-data:

Start it with docker compose up --build, inspect it with docker compose ps, and clean it up with docker compose down.