Why is Google Cloud Functions throwing a "Invalid value for config firebase.databaseURL" error when I try to initialize a firebase app? - node.js

Question

I have a Google Cloud Function that syncs presence information from a Firebase realtime database to a Firestore database (as explained here). This is the relevant Cloud Functions code from the linked example:
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
// Since this code will be running in the Cloud Functions enviornment
// we call initialize Firestore without any arguments because it
// detects authentication from the environment.
const firestore = admin.firestore();
// Create a new function which is triggered on changes to /status/{uid}
// Note: This is a Realtime Database trigger, *not* Cloud Firestore.
exports.onUserStatusChanged = functions.database.ref('/status/{uid}').onUpdate(
(change, context) => {
// Get the data written to Realtime Database
const eventStatus = change.after.val();
// Then use other event data to create a reference to the
// corresponding Firestore document.
const userStatusFirestoreRef = firestore.doc(`status/${context.params.uid}`);
// It is likely that the Realtime Database change that triggered
// this event has already been overwritten by a fast change in
// online / offline status, so we'll re-read the current data
// and compare the timestamps.
return change.after.ref.once('value').then((statusSnapshot) => {
const status = statusSnapshot.val();
console.log(status, eventStatus);
// If the current timestamp for this data is newer than
// the data that triggered this event, we exit this function.
if (status.last_changed > eventStatus.last_changed) {
return null;
}
// Otherwise, we convert the last_changed field to a Date
eventStatus.last_changed = new Date(eventStatus.last_changed);
// ... and write it to Firestore.
return userStatusFirestoreRef.set(eventStatus);
});
});
I recently received an email from Google informing me that I will need to update from NodeJS 6 to NodeJS 8 or 10. As this particular function isn't in production yet, I went ahead and made the configuration change in the Google Cloud Console. I now get the error below. I tried switching back to NodeJS 6, recreating the function from scratch, checking Github issues and other online forums. It appears that my Google Cloud Function is no longer being provided with the necessary environment variables to connect with Firebase/Firestore. However, I'm unsure why that would be the case.
Error: Invalid value for config firebase.databaseURL: undefined
at resourceGetter (/srv/node_modules/firebase-functions/lib/providers/database.js:101:19)
at cloudFunctionNewSignature (/srv/node_modules/firebase-functions/lib/cloud-functions.js:102:13)
at /worker/worker.js:825:24
at <anonymous> at process._tickDomainCallback (internal/process/next_tick.js:229:7)
This error also shows up in the Stackdriver logs for the Cloud Function:
Warning, estimating Firebase Config based on GCLOUD_PROJECT. Initializing firebase-admin may fail

Answer 1

You should redeploy using the Firebase CLI. It does some special things in the environment to help the Firebase Admin SDK initialize correctly without any parameters (adding FIREBASE_CONFIG). It sounds like when you changed the runtime in the console, you also lost this special configuration.

Answer 2

For me, I use firestore, and I was getting the same error as you, so I had to create a real-time database without any record then I set the credentials for the admin like so:
const functions = require("firebase-functions");
const admin = require("firebase-admin");
admin.initializeApp({
databaseURL: "your realtime database url"
});
When you are done, run firebase deploy --only functions to deploy your functions.
Here is your Realtime database URL: