Firebase: how to debug onCall functions?

Question

I am using Google Cloud Functions Emulator for debugging locally my Firebase functions. Firebase recommend to use functions.https.onCall functions instead of functions.https.onRequest for avoid using http calls directly. Instead Firebase recommend to use Firebase Functions SDK for call such functions from code. For functions.https.onRequest I used http-trigger flag but how can I debug onCall functions ?

Answer 1

I found a way to run 'onCall' cloud functions locally and call them from a local client. I still haven't figured out how to attach a debugger but at least I can iterate faster and use console.log statements.

Use firebase serve to host the functions. Even though these are supposed to be for http requests I found that the the firebase clients have a property to override the host name for onCall functions. This takes care of authentication and passing in the right data and context objects for you.

From Terminal in the root of your firebase project folder:

firebase serve

You should get a successful result in the terminal window. Take the hostname and port number:

✔ functions: helloWorld: http://localhost:5000/your-project-name/us-central1/helloWorld

iOS client:

Functions.functions().useFunctionsEmulator(origin: "http://localhost:5000")

NOTE: you have to disable App Transport Security in iOS for this to work

NOTE: other clients probably have the same API.