How to use mySQL and WIX adapter?

I am trying to follow the guide at: https://github com/wix/corvid-external-db-mysql-adapter
I have a MySQL instance running on Google Cloud but I want to connect this with WIX.

I am confused how the configuration section is supposed to be, where do we get the secret key?, the yaml gives me an error even when the socket path is configured correctly as I try to deploy it using Google App Engine.