Calling Firebase Cloud Functions Locally

Question

I know this question has been asked many times, and I've read all the answers, but still don't have a working solution.

I try to run my firebase functions and hosting locally with firebase serve or firebase emulators:start as described here and here.

This gives me something like:

✔  functions: Using node@8 from host.
✔  functions: Emulator started at http://127.0.0.1:8081
i  functions: Watching "/home/ec2-user/environment/functions" for Cloud Functions...
i  hosting: Serving hosting files from: build
✔  hosting: Local server: http://127.0.0.1:8080
⚠  functions: Your GOOGLE_APPLICATION_CREDENTIALS environment variable points to XXXXX-d5435114eb69.json. Non-emulated services will access production using these credentials. Be careful!
✔  functions[log]: http function initialized (http://127.0.0.1:8081/XXXXX/us-central1/log).

The hosting server works perfectly, and there is a log cloud function initialized at http://127.0.0.1:8081/XXXXX/us-central1/log. But running:

const log = firebase.functions().httpsCallable('log');
log("Hello World");

from the local hosted site tries to call the deployed cloud function and gives me a CORS error:

Access to fetch at 'https://us-central1-XXXXX.cloudfunctions.net/log' from origin 'http://127.0.0.1:8080' has been blocked by CORS policy

I'm using the firebase auto configuration to load the sdk.

Is it possible to run both hosting and functions locally for development?

Pascal Pascal · Accepted Answer · 2019-12-07T10:08:30

I had the same issue and my solution was simple, I used https.onRequest instead of https.onCall:

Not working:

// Cloud Function
exports.testFunction = functions.https.onRequest((request, response) => {
  response.send("Hello from Firebase!");
})

Working:

// Cloud Function
exports.testFunction = functions.https.onCall(() => {
  return { message: "Hello from Firebase!" }
})

Maybe that's your issue too?

Calling Firebase Cloud Functions Locally

1 Answers