docker-compose configuration

What is docker-compose?

Docker-compose is a useful tool for orchestrating multi-container Docker applications. It allows you to run applications based on a YAML file. These files are a list of instructions specifying the parameters of the applications to be launched.

In our example, we will run two containers – a MySQL database and a basic WordPress web application.

Docker build files might look like this:


version: '3.3'

services:
   db:
      image: mysql:5.7
      volumes:
         - db_data:/var/lib/mysql
      restart: always
      environment:
         MYSQL_ROOT_PASSWORD: somewordpress
         MYSQL_DATABASE: wordpress
         MYSQL_USER: wordpress
         MYSQL_PASSWORD: wordpress

   wordpress:
      depends_on:
         - db
      image: wordpress:latest
      ports:
         - "8000:80"
      restart: always
      environment:
         WORDPRESS_DB_HOST: db:3306
         WORDPRESS_DB_USER: wordpress
         WORDPRESS_DB_PASSWORD: wordpress
         WORDPRESS_DB_NAME: wordpress
      volumes:
         db_data: {}

How to manage a multi-container application with docker-compose?

We can use some basic docker-compose commands to manage containers:

Build or rebuild websites

docker-compose build

Create and run containers

docker-compose up

As you can see, the containers have been launched and the logs printed on the console. To run in the background, use the -d parameter.

Run a one-time command on the website

docker-compose run
ex: docker-compose run wordpress

For example, you can print the Debian version of the WordPress container.

Show list of running containers

docker ps

The docker ps command shows:

• container ID,
• name and version of the image,
• how long ago the container was created,
• status,
• ports and container name.

Print a list of information about running containers from the current docker-compose.yaml file

docker-compose ps

Show all logs in the container since its launch

docker logs <service>

Stop and delete containers, networks, volumes and images created with the “up” command

docker-compose down

Kill one or more running containers

docker kill <container_id>

Show image list

docker images

Execute the command in a running container

docker exec <service> <bash_command>

Delete all unused data

docker system prune

Useful command combinations

Kill all running containers

docker kill $(docker ps -q)

Stop all running containers

docker stop $(docker ps -q)

Delete all images

docker rmi $(docker images -q)

Remove all containers

docker rm $(docker container ps -q)

Summary

Docker-compose is a useful and easy tool for managing multiple containers. You can decide how containers are separated, what resources they can use and how they communicate with each other. You can also set what happens if the status of one of the containers changes. This feature allows you to automatically restore your system state.

More Docker configurations

dockerfile