DockerIntermediate9 min read2026-03-01

Docker Compose for Multi-Container Environments

Orchestrate full-stack applications with web servers, databases, and caches using docker-compose.yml.

Prerequisites

Docker basics

1. Composing an App with PostgreSQL and Redis

Define isolated networking, volumes, and healthchecks in a single configuration.

yaml

version: '3.8'
services:
  app:
    build: .
    ports:
      - "3000:3000"
    environment:
      DATABASE_URL: postgres://postgres:secret@db:5432/myapp
    depends_on:
      db:
        condition: service_healthy

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

volumes:
  pgdata:

Best Practices & Architecture Advice

Use named volumes for persistent data so database records survive container restarts.
Never commit production secrets in docker-compose.yml; use .env files.

Common Mistakes to Watch Out For

•Using localhost to connect between compose services instead of their service name (e.g. host 'db').

Frequently Asked Questions

How do services communicate with each other in Docker Compose?

Compose automatically creates a default shared bridge network where services resolve each other by their service name (e.g. 'db', 'redis') via internal DNS.