Prevent public access to staging app in my Heroku pipeline

问题

I have a Heroku pipeline with a staging app and a production app. I want to restrict access to the staging app so that features that are being tested (in staging) are not publicly accessible. How do I do that?

来源：https://stackoverflow.com/questions/46375386/prevent-public-access-to-staging-app-in-my-heroku-pipeline