LKNOG Wiki

'What is Docker Compose?'

Docker Compose is a tool for defining and running multi-container Docker applications. With Compose, you can define a multi-container application in a single file, then spin up your application with a single command (docker compose up).

'Key Concepts'

  Services: Each container started by Docker Compose is a service. Services are defined in the compose.yaml file.
  Networks: By default, Docker Compose sets up a single network for your application. Each container for a service joins the default network and is discoverable via a hostname identical to the container name.
  Volumes: Volumes can be used to share files between the host and container or between containers.

'Basic docker compose Commands'

• ` docker compose up`: Starts up the services defined in the compose.yaml file. • ` docker compose down`: Stops and removes all the containers defined in the compose.yaml file. • ` docker compose ps`: Lists the services and their current state (running/stopped). • `docker compose logs`: Shows the logs from the services.

'Deploying !WordPress with Docker Compose'

Let's deploy a !WordPress application using two containers: one for !WordPress and another for the MySQL database. Create a compose.yaml file:

version: '3'

services:

# Database Service
db:
  image: mysql:5.7
  volumes:
    - db_data:/var/lib/mysql
  environment:
    MYSQL_ROOT_PASSWORD: somewordpress
    MYSQL_DATABASE: wordpress
    MYSQL_USER: wordpress
    MYSQL_PASSWORD: wordpress

# WordPress Service
wordpress:
  depends_on:
    - db
  image: wordpress:latest
  ports:
    - "8080:80"
  environment:
    WORDPRESS_DB_HOST: db:3306
    WORDPRESS_DB_USER: wordpress
    WORDPRESS_DB_PASSWORD: wordpress
    WORDPRESS_DB_NAME: wordpress
  volumes:
    - wordpress_data:/var/www/html

volumes:

  db_data: {}
  wordpress_data: {}

'Start the !WordPress and Database Containers:'Navigate to the directory containing the `compose.yaml` file and run:

`docker compose up -d`

This command will start the services in detached mode. Once the services are up, you can access the !WordPress site by navigating to `http:<MASTER_IP>:8080` from your browser. 'Stopping the Services:' To stop the services, navigate to the same directory and run: 'docker compose down' Best Practices * Explicit Service Names: Give your services explicit names to make it clear what each service does. * Environment Variables: Use environment variables for sensitive information and configurations. * Service Dependencies: Use the depends_on option to ensure services start in the correct order.