What's happening behind the scenes when you use our CLI?
From the command line, Doorman prompts you to log in to your Firebase account and deploys a cloud function on your behalf. This is all done locally on your machine – Doorman never receives any of your Google credentials.
The cloud function Doorman deploys first validates requests to ensure they're coming from Doorman (using your Doorman secret key). Next, then generates a custom auth token for the user requested by Doorman.