How to setup variables for a kernel?

I am not able to find any concrete documentation for this project. I want to use beakerX to sql notebooks by connecting them to presto. I installed beakerx and I am able to connect to presto using the driver, however I don't want to expose connection detail in every notebook (presto credentials and config would be same for every notebook). How can I make use of variables like BEAKERX_SQL_DEFAULT_JDBC or where can I find of available variables and information on how to setting them up globally?

Start by investigating how BeakerX SQL notebooks and the driver consume BEAKERX_SQL_DEFAULT_JDBC and related configuration variables. Document the available variables and the supported way to configure shared Presto connection details globally, with a concrete example showing that notebooks no longer need repeated credentials and config.

Written by the indexing model from the issue text.