Firebase add admin user (with admin custom claim) to tenant

index.js

import admin from 'firebase-admin';
import { initializeApp } from 'firebase-admin/app';
initializeApp({
  apiKey: process.env.API_KEY,
  authDomain: process.env.AUTH_DOMAIN,
  credential: admin.credential.applicationDefault(),
  projectId: process.env.PROJECT_ID,
});

export const addAdminUser = (req, res) => {
  if (!req.body.email || req.body.email === '') {
    const error = 'The email must be a valid non-empty string.';
    console.error(error);
    res.status(400).send(error);
    return;
  }
  if (!req.body.password || req.body.password === '') {
    const error = 'The password must be a valid non-empty string.';
    console.error(error);
    res.status(400).send(error);
    return;
  }
  const tenantManager = admin.auth().tenantManager();
  const tenantAuth = tenantManager.authForTenant(req.body.tenantId);
  tenantAuth
  .createUser({
    email: req.body.email,
    emailVerified: false,
    password: req.body.password,
    disabled: false,
  })
  .then((userRecord) => { 
    tenantAuth.setCustomUserClaims(userRecord.uid, {admin: true});
    console.log('Successfully created new admin user:', userRecord.uid);
    res.status(200).send(userRecord.uid);
    return;
  })
  .catch((error) => {
    console.error('Error creating new user:', error);
    res.status(400).send(error);
    return;
  });
};

package.json

{
  "name": "tenant-add-user",
  "version": "1.0.0",
  "description": "Adds user to tenant in Cloud Identity Platform with a custom claim: {admin: true}",
  "main": "index.js",
  "type": "module",
  "scripts": {
    "start": "functions-framework --target=addAdminUser -r dotenv/config ",
    "test": "echo \"Error: no test specified\" && exit 1",
    "debug": "node --inspect node_modules/.bin/functions-framework --target=addAdminUser -r dotenv/config"
  },
  "author": "Mauricio Caro",
  "license": "ISC",
  "dependencies": {
    "@google-cloud/functions-framework": "^3.1.2",
    "firebase-admin": "^11.3.0"
  },
  "devDependencies": {
    "dotenv": "^16.0.3"
  }
}