Docker Compose Commands

Introduction

Docker Compose is a powerful tool that allows you to define and manage multi-container Docker applications. Instead of using multiple Docker commands to create, start, and connect containers, Docker Compose enables you to use a single YAML file to configure your application's services and execute a single command to create and start all the services.

This guide covers the essential Docker Compose commands you'll need to work with multi-container applications effectively. By the end, you'll be comfortable creating, running, and managing complex Docker environments.

Getting Started with Docker Compose

Before diving into the commands, make sure you have Docker and Docker Compose installed on your system. You can check your installations with:

bash

docker --version
docker-compose --version

A Docker Compose file (typically named docker-compose.yml) defines the services, networks, and volumes for your application. Here's a simple example:

yaml

version: '3'
services:
  web:
    image: nginx:latest
    ports:
      - "8080:80"
  database:
    image: mysql:5.7
    environment:
      MYSQL_ROOT_PASSWORD: example

This file defines two services: a web server using the Nginx image and a database using MySQL.

Essential Docker Compose Commands

1. Creating and Starting Containers

docker-compose up

This command builds, creates, and starts all services defined in your docker-compose.yml file.

bash

# Start all services
docker-compose up

# Start in detached mode (background)
docker-compose up -d

# Build images before starting containers
docker-compose up --build

Output example:

Creating network "myapp_default" with the default driver
Creating myapp_database_1 ... done
Creating myapp_web_1      ... done
Attaching to myapp_database_1, myapp_web_1
database_1  | 2023-04-10T10:15:23.334Z [Note] [Entrypoint]: Entrypoint script for MySQL Server started.
web_1       | /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration

2. Stopping Containers

docker-compose down

This command stops and removes all containers, networks, and volumes defined in the Docker Compose file.

bash

# Stop and remove containers, networks
docker-compose down

# Additionally remove volumes
docker-compose down --volumes

# Additionally remove images
docker-compose down --rmi all

docker-compose stop

This command stops running containers without removing them.

bash

# Stop all services
docker-compose stop

# Stop specific service
docker-compose stop web

3. Viewing Container Status

docker-compose ps

This command lists all containers related to the services defined in your Docker Compose file and their status.

bash

docker-compose ps

Output example:

       Name                     Command               State           Ports
----------------------------------------------------------------------------------
myapp_database_1    docker-entrypoint.sh mysqld      Up      3306/tcp, 33060/tcp
myapp_web_1         /docker-entrypoint.sh ngin ...   Up      0.0.0.0:8080->80/tcp

4. Viewing Logs

docker-compose logs

This command displays log outputs from services.

bash

# View logs of all services
docker-compose logs

# View logs of a specific service
docker-compose logs web

# Follow log output
docker-compose logs -f

# Show last 10 lines
docker-compose logs --tail=10

5. Executing Commands in Containers

docker-compose exec

This command executes a command in a running container.

bash

# Open a shell in the web service container
docker-compose exec web bash

# Run a specific command
docker-compose exec database mysql -u root -p

6. Building Images

docker-compose build

This command builds or rebuilds services defined in the Docker Compose file.

bash

# Build all services
docker-compose build

# Build a specific service
docker-compose build web

# Build with no cache
docker-compose build --no-cache

7. Pulling Images

docker-compose pull

This command pulls the latest images for services defined in the Docker Compose file.

bash

# Pull all images
docker-compose pull

# Pull a specific service's image
docker-compose pull database

8. Creating Service Configuration

docker-compose config

This command validates and displays the composition file after processing.

bash

# Check if docker-compose.yml is valid
docker-compose config

# Check a specific file
docker-compose -f custom-compose.yml config

9. Scaling Services

docker-compose up --scale

This command scales a service to a specified number of instances.

bash

# Scale the web service to 3 instances
docker-compose up -d --scale web=3

Output example:

Creating myapp_web_1 ... done
Creating myapp_web_2 ... done
Creating myapp_web_3 ... done

Practical Examples

Example 1: Setting Up a Web Application with Database

Let's create a simple web application with a front-end, backend API, and database:

yaml

version: '3'
services:
  frontend:
    image: node:14
    working_dir: /app
    volumes:
      - ./frontend:/app
    command: npm start
    ports:
      - "3000:3000"
    depends_on:
      - api

  api:
    image: node:14
    working_dir: /app
    volumes:
      - ./api:/app
    command: npm start
    ports:
      - "4000:4000"
    depends_on:
      - db
    environment:
      - DB_HOST=db
      - DB_USER=root
      - DB_PASSWORD=example
      - DB_NAME=myapp

  db:
    image: mysql:5.7
    ports:
      - "3306:3306"
    environment:
      - MYSQL_ROOT_PASSWORD=example
      - MYSQL_DATABASE=myapp
    volumes:
      - db-data:/var/lib/mysql

volumes:
  db-data:

To set up and run this application:

bash

# Start all services in detached mode
docker-compose up -d

# Check status
docker-compose ps

# View API logs
docker-compose logs api

# Execute MySQL command
docker-compose exec db mysql -u root -p -e "SHOW DATABASES;"

Example 2: Development vs. Production Configuration

You can use multiple compose files for different environments:

docker-compose.yml (base configuration):

yaml

version: '3'
services:
  app:
    build: .
    ports:
      - "8000:8000"
  db:
    image: postgres:13
    volumes:
      - db-data:/var/lib/postgresql/data

volumes:
  db-data:

docker-compose.override.yml (development overrides, applied automatically):

yaml

version: '3'
services:
  app:
    volumes:
      - ./app:/app
    environment:
      - DEBUG=true
  db:
    ports:
      - "5432:5432"

docker-compose.prod.yml (production overrides):

yaml

version: '3'
services:
  app:
    environment:
      - DEBUG=false
    restart: always
  db:
    restart: always

To use these configurations:

bash

# For development (uses docker-compose.yml + docker-compose.override.yml automatically)
docker-compose up -d

# For production (specify both files)
docker-compose -f docker-compose.yml -f docker-compose.prod.yml up -d

Docker Compose Command Flow

Here's a typical workflow with Docker Compose:

Summary

Docker Compose provides a streamlined way to manage multi-container applications through a single YAML file and simple commands. The key commands we've covered are:

• docker-compose up: Create and start containers
• docker-compose down: Stop and remove containers
• docker-compose ps: View container status
• docker-compose logs: View logs
• docker-compose exec: Execute commands in containers
• docker-compose build: Build or rebuild services
• docker-compose pull: Pull service images
• docker-compose config: Validate configuration
• docker-compose up --scale: Scale services

By mastering these commands, you'll be able to efficiently develop, test, and deploy complex applications using Docker Compose.

Additional Resources

• Docker Compose Documentation
• Docker Compose File Reference

Exercises

1. Create a docker-compose.yml file that runs a WordPress site with a MySQL database.
2. Modify an existing Docker Compose file to scale a service to multiple instances.
3. Create separate development and production Docker Compose configurations for an application.
4. Set up a multi-container application with proper dependency order and networking.
5. Use Docker Compose to set up a local development environment for a web application with frontend, backend, and database components.