From time to time there is the need to log into a containerized MySQL instance. And of course, when this time comes, I have completely forgotten how this works. Consequently, I should write it down. Here you go:

Bash into the running container

docker exec -t -i <container_id> /bin/bash

Usually, you should end up with something like the following:

root@localhost:~# docker exec -t -i 365a8a95c335 /bin/bash
root@365a8a95c335:/#

Log into MySQL

mysql -u “<useranme>” -p

Once again, it should look similar to the following:

root@365a8a95c335:/# mysql -u "wpuser" -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g. 
Your MySQL connection id is 146
Server version: 5.7.24 MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved

Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement

mysql>

Now you should be able to do whatever you want to do with MySQL.