Draxlr has a Heroku Marketplace App that you can use to easily connect Draxlr to your database of the Heroku app.
Follow this link to see Draxlr’s Heroku Marketplace Listing.
From there, Click on Install Draxlr for Postgres/MySQL button to install the integration. In the next step, you'll have to select the Heroku App you want this integration to be installed. Search and select your App. Then hit the Submit Order Form button. Wait for a few seconds and Draxlr Add-on is added to your Heroku App. Watch the video below for reference. Once done, move to the next step to select and connect your Heroku database to Draxlr.
Once you have added the integration. Go to the Resources Tab in Heroku and click on the Draxlr Integration. It’ll take you to the Draxlr App, once you are in the Draxlr app, you may need to fill up some basic details(name, organization, etc). Once done hit the Continue button. That will take you to the Connect Database page. Here you have two options, Either you can connect any database from your Heroku App or you can manually add any other database. Clicking on Connect Heroku Database asks you for your permission to Provide Draxlr with the list of databases. Hit Allow, and you’ll get the list of databases, Choose the database you want to connect with Draxlr and Done. You’ll be redirected to Draxlr app with your database setup.