I use Salesforce for my CRM, but you need to request data (multiple records, therefore no Zapier) for a Heroku-based Sinatra application. Heroku provides a service that regularly replicates Salesforce objects to Postgres tables, which retrieve my data from Salesforce.
I precoded the Sinatra application and posted it on Heroku, so I am a little familiar with the process of creating dev db locally, and then dragged it to production through a lot of tutorials. However, I ran into the problem of finding any information that would allow me to connect to the existing Postgres DB database, which is already filled with the data I need, while there is no need to create and connect to the local dev db.
Heroku provides me with the following

How and where can I connect these various credentials safely, so my next files have the correct information for connecting to Venue__c and Spaces__c tables?
app.rb
/ config
- database.yml
- environment.rb