Docker Compose #

Docker Compose is a tool for defining and running multi-container Docker applications using a declarative YAML file called docker-compose.yml. It makes it easy to configure, manage, and scale containerized applications by providing a simple way to define each service, its dependencies, and how they should interact.

In this section, we’ll set up a LAMP stack (Linux, Apache, MySQL, and PHP) using Docker Compose to deploy a PHP website available on the web.

Creating the Docker Compose File #

Create a new file named docker-compose.yml in your project directory and add the following content:

services:
  web:
    image: php:8.1-apache
    volumes:
      - ./public:/var/www/html
    ports:
      - "80:80"
    depends_on:
      - db

  db:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: my_root_password
      MYSQL_DATABASE: my_database
      MYSQL_USER: my_user
      MYSQL_PASSWORD: my_password
    volumes:
      - db_data:/var/lib/mysql

  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    ports:
      - "8080:80"
    environment:
      PMA_HOST: db
      PMA_USER: my_user
      PMA_PASSWORD: my_password
    depends_on:
      - db

volumes:
  db_data:

This docker-compose.yml file defines three services:

1. web: This service uses the php:8.1-apache image and maps the public directory on the host to the Apache document root /var/www/html inside the container. It also exposes port 80 on the host.

2. db: This service uses the mysql:8.0 image and sets up environment variables for the root password, database name, and user credentials. It creates a named volume db_data to persist the MySQL data.

3. phpmyadmin: This service uses the phpmyadmin/phpmyadmin image to provide a web interface for managing the MySQL database. It exposes port 8080 on the host and sets up environment variables for the database connection.

Creating the PHP Website #

Create a new directory named public in your project directory and add your PHP files there. For example, you can create a simple index.php file with the following content:

<?php
  $conn = new mysqli('db', 'my_user', 'my_password', 'my_database');
  if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
  }

  echo "Connected to MySQL successfully!";

This PHP script connects to the MySQL database using the credentials defined in the docker-compose.yml file.

Running the LAMP Stack #

In your terminal, navigate to the project directory containing the docker-compose.yml file and run the following command:

docker-compose up -d

Docker Compose will pull the required images, create the containers, and set up the network connections as defined in the docker-compose.yml file.

Once the containers are running, you can access the PHP website at your public DNS address.

The phpMyAdmin interface should be available on port :8080.

To stop the containers, run the following command in the project directory:

docker-compose down

This command will stop and remove the containers, networks, and any anonymous volumes created by docker-compose up. Note that the named volume db_data will not be removed automatically to ensure data persistence. If you want to remove the named volumes as well, you can use the --volumes or -v flag:

docker-compose down --volumes

Keep in mind that using this flag will delete the named volumes and all the data stored in them.

Docker Compose simplifies the process of managing and running multi-container applications. By defining the services, volumes, and network connections in a single docker-compose.yml file, we can easily start, stop, and scale our application as needed.