phpMyAdmin is a great tool for managing MySQL databases and is available as a docker image. The setup in a docker-compose environment is not as straight forward as it seems at first sight. That is why I break things down to make it more managable and easier to understand.

The Problem

• links are deprecated
• root users require sudo to login
• users work only on localhost

phpMyAdmin comes as an image and a look at the documentation is enought to figure out that the setup is rather simple. You first run a container base off a MySQL image or MariaDB image and then you run your phpMyAdmin container using a link to connect both containers. The problem is that links are deprecated and using them inside a docker-compose file will be ignored. Furthermore, you cannot use the root user to login into phpMyAdmin as this requires the sudo command.

At first glance, we can bypass the problem with the root user by creating a user using the environment variables that phpMyAdmin and MySQL gives to create a new user but this gives us another problem. A user works only on the localhost of that container. If you want to log into the MySQL database from the phpMyAdmin container you are accessing a remote database outside of the localhost which is why you need to create a user that uses any host.

Using named Volumes

I use named volumes to persist my databases and share them across different projects which is why we start by creating one if we don’t already have one:

docker volume create mysqldb

Creating a User with privileges

Now we can create our user with privileges. For that we have to run a MySQL container to have the MySQL server running and then we have to log into that MySQL container to create a user:

docker container run -v mysqldb:/var/lib/mysql \
--environment MYSQL_ROOT_PASSWORD=secret mysql --name mysqlserver

# open a new tab or window
docker container exec -it -v mysqldb:/var/lib/mysql mysqlserver mysql -p

# enter your root password set above as 'secret'

Now we are logged into the mysql database and we can create the user. Change alexander to your username and secret with your password. The % sign tells MySQL to allow any host with that username to access the database using the password.

GRANT ALL PRIVILEGES ON *.* TO 'alexander'@'%' IDENTIFIED BY 'secret';
exit;

Writing the docker-compose file

As we learned earlier links are deprecated but we don’t need links to access our container as long as they are on the same network and docker compose creates one network and puts all the services in it default:

version: '3.2'

services:
  db:
    image: mysql
    volumes:
    - mysqldb:/var/lib/mysql
    container_name: db

  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    environment:
      - PMA_HOST=db
      - PMA_USER=alexander
      - PMA_PASSWORD=secret
    ports:
      - 8000:80

volumes:
  mysqldb:
    external: true

We specify a service a service for our database and then we pass the host, user and password to our phpMyAdmin service through the environment variables.