Reset Root Password in MariaDB + MySQL in Docker and Docker Swarm

2 min read | #stackoverflowish: Couldn't find an answer on Stackoverflow so I wrote a quick blog post about it

Note to myself: do not delete your docker swarm cluster when using docker secrets for your docker based databases ;)

In case you do, you have to reset the passwords in the docker databases.

Change your docker compose file and add the argument --skip-grant-tables which can be done by using command in your docker compose file. If you haven’t used command in your docker compose, just add the line below or just add the argument if you already use command.

version: "3.7"
    image: mariadb
      - mysqldata:/var/lib/mysql
      MYSQL_DATABASE: mydb
      MYSQL_USER: myuser
      MYSQL_ROOT_PASSWORD_FILE: /run/secrets/db_root_password
      MYSQL_PASSWORD_FILE: /run/secrets/db_password
      - db_root_password
      - db_password
    command: --skip-grant-tables

After this change restart your docker container and login to it.

$ sudo docker ps | grep project_db
29b86cab6d42 mariadb:10 ...

$ sudo docker exec -it 29b86cab6d42 bash
root@29b86cab6d42:/# mysql -u root

Don’t forget to flush privileges otherwise you will get the following errors while trying to change the password:

MariaDB [mysql]> update user SET PASSWORD=PASSWORD("newpassword") WHERE USER='root';
ERROR 1348 (HY000): Column 'Password' is not updatable
MariaDB [mysql]> ALTER USER 'root'@'localhost' IDENTIFIED BY 'new password';
ERROR 1290 (HY000): The MariaDB server is running with the --skip-grant-tables option so it cannot execute this statement

So flush privileges and alter the root password. Usually you have two different root users, one for localhost and one for everything else, so don’t forget to alter the second one.

MariaDB [mysql]> flush privileges;
Query OK, 0 rows affected (0.002 sec)

MariaDB [mysql]>  ALTER USER 'root'@'localhost' IDENTIFIED BY 'newpassword';
Query OK, 0 rows affected (0.005 sec)
MariaDB [mysql]>  ALTER USER 'root'@'%'  IDENTIFIED BY 'newpassword';
Query OK, 0 rows affected (0.007 sec)

In case you have specified a MYSQL_USER in your docker compose file, also change the password of this user. In case you have already generated new docker secrets, just use the password specified in the files in /run/secrets.

The last step is to remove the --skip-grant-tables in your docker compose file and restart the container using docker compose.