Heroku is a free cloud hosting service that lets you scale and things.
Using MySQL with Rails applications on Heroku
This is actually very difficult because by default Heroku overwrites your
database.yml, you need to follow the instructions for Configuring your Ruby application to use ClearDB:
heroku config | grep CLEARDB_DATABASE_URL heroku config:set DATABASE_URL='mysql://example:email@example.com/heroku_db?reconnect=true'