create user uid in firestore
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
const db = admin.firestore();
exports.createUser = functions.auth.user().onCreate((user) => {
const { uid } = user;
const userCollection = db.collection('users');
userCollection.doc(uid).set({
someData: "123"
});
});