New Relic - Apdex

Requirements

To use New Relic API v2 you must either use their "Pro" plan, or their free New Relic add-on via Heroku.

Authentication

Finding your credentials (New Relic Account ID, App ID and REST API Key) isn't very straightforward.

1. Log-in to New Relic's web interface.
2. Click on the "Applications" tab in the upper left corner.
3. Click on your desired application.
4. Now grab the account id and app id from the URL. /accounts/ACCOUNT_ID/applications/APP_ID 
5. Now, click on your user account in the upper right corner to expand a menu.
6. Click on "Account Settings".
7. Click on "Api keys" in the sidebar.
8. Here you should be able to activate/find/(re)generate API REST keys

HireFire UI

Once you've obtained the necessary credentials, log in to HireFire and create a manager, using web  as its name (must be called web , all lowercase, to reflect the Procfile entry web ), set the Type to  Web.NewRelic.V2.Apdex , configure the rest of the options to your liking and then save and enable the manager.

Once all of that's done, HireFire will be auto-scaling your web dynos.