Change root password in MariaDB Docker container running with docker-compose

1. Override the entrypoint in docker-compose.yml for the MariaDB Docker container by adding:

entrypoint: mysqld_safe --skip-grant-tables --user=mysql

2. The start up the Docker Compose stack:

$> docker-compose up -d

3. Then login to the Docker container:

$> sudo docker exec -ti docker-container-name bash

4. And login as root without password:

$> mysql -u root -p

5. Change the root password in mysql cli:

mysql> FLUSH PRIVILEGES;
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'your_secret';
mysql> FLUSH PRIVILEGES;

6. Logout of mysql and the Docker container (2x exit), remove the entrypoint line from the docker-compose.yml and reload the Docker Composer stack:

$> docker-compose up -d

7. You can now login to the MariaDB container and connect to the database with the new root password:

$> sudo docker exec -ti docker-container-name bash
$> mysql -u root -p

For mariadb:

entrypoint: /usr/bin/mariadbd-safe --skip-grant-tables --user=mysql
mariadb -u root -p

All this because I didn't realize it only printed the original root password once, which is long-lost.