Running Rails Development with a Fake Domain and SSL

Sometimes you need to test a feature that requires not just SSL (https) but also to run under a certain domain. For example, testing an OAuth application will mean running your development environment at the right callback URL, especially when the OAuth provider doesn't support custom callbacks. Another example is testing FIDO or WebAuthn support: not only do these features need to run via SSL, but also under the right domain, which is not where your app will typically run before it's rolled out to production.This is a quick guide to a workaround to get your the development branch of your Rails app running via SSL and under your production URL.