We pass in quantum's sql connection string to the controller, but set the database up in the controller block

I'm reading this as "there should be one source of truth but there isn't; therefore there's a chance that if someone changes one bit but not the other things could get broken". Correct?

Yes. It appears that you can change the SQL string and that's it; but the internal database setup sets up precisely that DB. If you change the SQL string that DB is still set up.

The SQL connection information is exposed to the site/core manifest so we can leverage the controller_node_address variable. Separate SQL connections are used for services to give customers the option for providing unique user credentials. Here is an example from my core manifest:

ovs_sql_connection => "mysql://quantum:${quantum_db_password}@${controller_node_internal}/quantum",

The question is if we're passing the same information twice in different forms: once as the connection string, once as individual components to actually install the database. Bad if so.