Comprehensive Docker Compose Guide

Docker Compose is a powerful tool that helps define and manage multi-container Docker applications. This article will help you master the basic commands and useful techniques when working with Docker Compose.

Basic Commands

1. docker-compose up

Function: Create and start all containers defined in the docker-compose.yml file

Syntax: docker-compose up [options] [SERVICE…]

Common options:

• -d: Run in detached mode (background)
• –build: Rebuild images before starting
• –force-recreate: Recreate containers even if their configuration hasn’t changed
• –no-deps: Don’t start dependent services

Examples:

docker-compose up -d

docker-compose up -d –build app

2. docker-compose down

Function: Stop and remove containers, networks, and volumes (optional)

Syntax: docker-compose down [options]

Common options:

• –volumes or -v: Remove volumes as well
• –remove-orphans: Remove containers not defined in the configuration
• –rmi [all|local]: Remove images

Examples:

docker-compose down

docker-compose down -v

3. docker-compose ps

Function: List containers belonging to the project

Syntax: docker-compose ps [options] [SERVICE…]

Common options:

• -q: Only display IDs
• –services: Only display service names

Examples:

docker-compose ps

docker-compose ps -q

4. docker-compose logs

Function: View logs from services

Syntax: docker-compose logs [options] [SERVICE…]

Common options:

• -f: Follow log output
• –tail=N: Display the last N lines
• –timestamps: Show timestamps

Examples:

docker-compose logs -f

docker-compose logs –tail=100 app

Container Management Commands

1. docker-compose exec

Function: Execute a command in a running container (similar to SSH)

Syntax: docker-compose exec [options] SERVICE COMMAND

Common options:

• -T: Don’t allocate a pseudo-TTY
• –index=N: Specify the container if there are multiple instances
• -u USER: Run the command as a specific user

Examples:

docker-compose exec app bash

docker-compose exec -u root db mysql -u root -p

2. docker-compose run

Function: Run a one-time command on a service, creating a new container

Syntax: docker-compose run [options] SERVICE [COMMAND]

Common options:

• –rm: Automatically remove the container when finished
• -d: Run in detached mode
• –no-deps: Don’t start dependent services
• -e KEY=VAL: Set environment variables

Examples:

docker-compose run –rm app npm test

docker-compose run -e NODE_ENV=test app node script.js

3. docker-compose restart

Function: Restart services

Syntax: docker-compose restart [options] [SERVICE…]

Common options:

• -t, –timeout TIMEOUT: Time to wait before forcing stop (default: 10 seconds)

Examples:

docker-compose restart

docker-compose restart -t 30 app

4. docker-compose stop

Function: Stop running services

Syntax: docker-compose stop [options] [SERVICE…]

Common options:

• -t, –timeout TIMEOUT: Time to wait before forcing stop (default: 10 seconds)

Examples:

docker-compose stop

docker-compose stop app db

5. docker-compose start

Function: Start previously created services

Syntax: docker-compose start [SERVICE…]

Examples:

docker-compose start

docker-compose start app db

6. docker-compose pause/unpause

Function: Pause or unpause services

Syntax:

• docker-compose pause [SERVICE…]
• docker-compose unpause [SERVICE…]

Examples:

docker-compose pause app

docker-compose unpause app

7. docker-compose top

Function: Display running processes in each container

Syntax: docker-compose top [SERVICE…]

Examples:

docker-compose top

docker-compose top app

Container Interaction Techniques (Similar to SSH)

Docker Compose provides multiple ways to interact with containers, similar to using SSH:

1. Create an interactive shell

docker-compose exec web /bin/bash

docker-compose exec app /bin/sh

2. Copy files between the host machine and the container

docker cp $(docker-compose ps -q app):/app/data.json ./local/path/

3. Execute commands with root privileges

docker-compose exec -u root app bash

4. Execute complex shell commands

docker-compose exec app sh -c “cd /app && bash”

5. Check environment variables in a container

docker-compose exec app env

6. Run commands as a specific user

docker-compose exec -u postgres db psql -U postgres

7. Run commands in a specific directory

docker-compose exec app sh -c “cd /var/log && ls -la”

8. Transfer files from the host machine to a container

docker cp ./config.json $(docker-compose ps -q app):/app/config.json

Tips and Best Practices

1. Use .env files: Store environment variables in .env files to increase security and flexibility
2. Name your project: Use -p to name your project to avoid conflicts
3. Use version control: Always keep your docker-compose.yml file in a version control system
4. Separate development and production environments: Use separate docker-compose files for different environments

Conclusion

Docker Compose is an essential tool for managing multi-container Docker applications. With the commands and techniques presented above, you can easily deploy, manage, and debug complex applications in containerized environments.