Lab 005: Docker Compose - WordPress & MariaDB ¶

This lab demonstrates how to use Docker Compose to orchestrate a simple multi-container application: WordPress with a MariaDB database backend.

Overview¶

• The provided docker-compose.yaml file defines two main services:

• db: Runs a MariaDB database (can be switched to MySQL if desired).

• wordpress: Runs the latest WordPress application, connected to the database.

• A named volume db_data is used to persist database data.

docker-compose.yaml Breakdown¶

• db service
• Uses the mariadb:10.6.4-focal image (or optionally MySQL).
• Sets up environment variables for root password, database, user, and password.
• Persists data in a Docker volume.

• Exposes ports 3306 and 33060 (internal only).

• wordpress service

• Uses the latest WordPress image.
• Maps port 80 on the host to port 80 in the container.

• Configures environment variables to connect to the database.

• volumes

• db_data: Persists MariaDB data between container restarts.

Bonus Demo¶

• I prepared a demo of this lab, which you can view on KillerCoda: Portainder Demo.
• The demo is showcases for setting and running multuple containers using Docker Compose
• The demo is available on KillerCoda.

How to Run the Lab¶

1. Navigate to the lab directory:

   cd Labs/005-DockerCompose
   

2. Start the services:

   docker compose up -d
   

3. This will pull the required images (if not already present) and start both the database and WordPress containers in detached mode.

4. Access WordPress:

5. Open your browser and go to http://localhost

6. Complete the WordPress setup wizard.

7. Stop the services:

   docker compose down
   

   This will stop and remove the containers, but the database data will persist in the db_data volume.

Notes¶

• To use MySQL instead of MariaDB, uncomment the relevant line in the compose file and comment out the MariaDB image line.
• The database credentials are set for demonstration purposes. For production, use secure passwords.
• The db service is only accessible to the wordpress service (not exposed to the host).

Troubleshooting¶

• If you encounter port conflicts, ensure nothing else is running on port 80.
• To view logs for a service:

  docker compose logs wordpress
  docker compose logs db
  

This lab is part of the DockerLabs series. See other labs for more Docker scenarios and hands-on exercises.