This is a docker-compose file for joomla dev versions (not ready for production!). Parts of this repo are taken from the official joomla docker repo.
You need to install docker-compose then clone this repository or take just the docker-compose file. In the file you may change the logins and passwords then fire it up with docker-compose up
You should be able then to access the joomla installation at http://localhost:8080 . In the database configuration dialog choose mysql as the Host Name and insert username, password and database name like it is configured in the docker-compose file.
https://sloppy.io is a docker hosting platform. You get free *.sloppy.zone domains and free lets encrypt ssl certificates for your own domains.
Here is a video how to setup up joomla at sloppy.io https://vimeo.com/206595268