sinatra-redirect-with-flash | flash provides redirect helper that can set | Plugin library

You don't need the other lines if you have the db url, it can be a 1 liner, and also let postgres timeout it's default, no need to set it. You probably want a larger pool size in prod. Go to the postgres database you should have added to your app in Heroku. Click on the View Credentials button. Copy the data from there to your local .env file and also add .env to your .gitignore file because you don't want to commit your private credentials to your public repo.

Then on heroku