Docker Compose: Orchestrating Multi-Container Applications

Introduction to Docker Compose

Docker Compose is a tool for defining and running multi-container Docker applications. With Compose, you use a YAML file to configure your application's services, networks, and volumes.

Basic docker-compose.yml Structure

A typical docker-compose.yml file defines services, networks, and volumes. Here's a simple example for a Laravel application.

version: '3.8'
services:
  app:
    build: .
    ports:
      - "8000:8000"
    volumes:
      - .:/var/www/html
    depends_on:
      - db

  db:
    image: mysql:8.0
    environment:
      MYSQL_DATABASE: laravel
      MYSQL_USER: laravel
      MYSQL_PASSWORD: secret
    volumes:
      - db_data:/var/lib/mysql

volumes:
  db_data:

Common Docker Compose Commands

Starting Services

• docker-compose up -d (start in background)
• docker-compose up --build (rebuild images)
• docker-compose logs (view logs)
• docker-compose down (stop and remove)

Networking in Docker Compose

By default, Compose sets up a single network for your app. Each container for a service joins the default network and is both reachable by other containers on that network, and discoverable by them at a hostname identical to the container name.

networks:
  frontend:
    driver: bridge
  backend:
    driver: bridge

services:
  web:
    networks:
      - frontend
      - backend
  api:
    networks:
      - backend
  db:
    networks:
      - backend

This network configuration allows for better isolation and security in complex applications.