Error: Could not load the default credentials. - Cloud Functions

Issue

I'm working on the group functionality for my react-native app. And I wish to send cloud messages to users who have been added when a group is created. I'm using cloud functions to do that.

But I am getting this error in my function:

Error: Could not load the default credentials. Browse to https://cloud.google.com/docs/authentication/getting-started for more information.
    at GoogleAuth.getApplicationDefaultAsync (/srv/node_modules/google-auth-library/build/src/auth/googleauth.js:161:19)
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:229:7)

Its unable to fetch the fcm-token from firestore to send the notification.

I had written cloud functions for sending friend requests and in that, the token is retrieved successfully from cloud firestore, and the notification is sent.

This is my cloud function :

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();

//======================NOTIFY ADDED MEMBERS==========================//

exports.notifyAddedMembers = functions.https.onCall((data, context) => {
  const members = data.members;
  const groupName = data.groupName;
  var tokens = [];
  members.forEach(async member => {
    //send notifications to member.uid
    console.log('MEMBER.UID ', member.uid);
    await fetchTokenFromUid(member.uid)
      .then(token => {
        console.log('retrieved token: ', token);
        // tokens.push(token);
        const payload = {
          notification: {
            title: `You have been added to ${groupName}`,
            body: 'Share your tasks',
            sound: 'default',
          },
        };
        return admin.messaging().sendToDevice(token, payload);
      })
      .catch(err => console.log('err getting token', err));
  });
  // console.log('ALL TOKENS: ', tokens);
  console.log('GROUP NAME: ', groupName);
});

async function fetchTokenFromUid(uid) {
  var token = '';
  return await admin
    .firestore()
    .collection('Users')
    .doc(`${uid}`)
    .get()
    .then(async doc => {
      console.log('uid token: ', Object.keys(doc.data().fcmTokens));
      var tokenArray = Object.keys(doc.data().fcmTokens); //ARRAY
      for (var i = 0; i < tokenArray.length; i++) {
        token = tokenArray[i]; //Coverts array to string
      }
      return token; //return token as string
    });
}

I am using the react-native-firebase library.

Solution

You are correctly loading the firebase-functions and firebase-admin modules, and initializing an admin app instance.

I don't know what exactly generates the error you got, but based on this SO Question it could be because, in your Cloud Function, you are mixing the use of async/await with the then() method.

Do you have any other Cloud Function(s) in your index.js file? In particular some that interact with other Google APIs.

I propose to refactor your code as follows, using Promise.all(). You first fetch all the tokens and then you send the messages.

exports.notifyAddedMembers = functions.https.onCall(async (data, context) => {

    try {
        const members = data.members;
        const groupName = data.groupName;

        const promises = [];
        members.forEach(member => {
            promises.push(admin
                .firestore()
                .collection('Users')
                .doc(member.uid).get());
        });

        const tokensSnapshotsArray = await Promise.all(promises);

        const promises1 = [];
        tokensSnapshotsArray.forEach(snap => {

            const token = snap.data().fcmToken;  //Here you may adapt as it seems you have an array of tokens. I let you write the loop, etc.

            const payload = {
                notification: {
                    title: `You have been added to ${groupName}`,
                    body: 'Share your tasks',
                    sound: 'default',
                },
            };
            promises1.push(admin.messaging().sendToDevice(token, payload));

        });

        await Promise.all(promises1);

        return { result: 'OK' }
    } catch (error) {
        //See the doc: https://firebase.google.com/docs/functions/callable#handle_errors
    }

});

Answered By - Renaud Tarnec