Install MariaDB on Debian 9
Create and publish documentation for your API, using swagger and docker. This is the kind of documentation developers who use your API will actually want.
Use swagger codegen to generate your code.
Install the postman app on Ubuntu 18.04
My new favourite database diagramming tool.
A cheatsheet for the commands you need for setting up Samba users etc.
Create an htaccess file that requires authentication for everywhere except a whitelist of routes.
Set your root password in Ubuntu 18.04 for MySQL.
Some tips for optimizing the Docker build process when you are setting permissions on a large number of files.
Install and use fdupes for finding and removing duplicate files.
Learn to create templates that you can then install using the composer create-project command.