Custom Firebase Hasura Claims with Firestore

index.js

const functions = require('firebase-functions')
const admin = require('firebase-admin')
const cors = require('cors')({
  origin: (origin, callback) => {
    const allowed = ['http://localhost:3000', 'https://yourfinalwebsite.com']
    if (allowed.indexOf(origin) !== -1) {
      return callback(null, true)
    }
    return callback(new Error(`CORS Policy denies ${origin}`), false)
  },
})
const Firestore = require('@google-cloud/firestore')

admin.initializeApp(functions.config().firebase)

const firestore = new Firestore({
  projectId: 'your-firebase-project-id',
  timestampsInSnapshots: true,
})

const updateClaims = (uid) => firestore.collection('claims').doc(uid).get().then((doc) => {
  if (!doc) { return {} }
  const data = doc.data()
  console.log(`${uid} has custom claims`, data)
  return data
})
  .then((additionalClaims) => {
    const defaultClaims = {
      'x-hasura-default-role': 'user',
      'x-hasura-allowed-roles': ['user'],
      'x-hasura-user-id': uid,
    }
    const claims = {
      'https://hasura.io/jwt/claims': {
        ...defaultClaims,
        ...additionalClaims,
      },
    }
    return admin.auth().setCustomUserClaims(uid, claims)
  })

exports.processSignUp = functions.auth.user().onCreate((user) => updateClaims(user.uid))

exports.refreshToken = functions.https.onRequest((req, res) => {
  console.log('TOKEN REFRESH', req.query.uid)
  cors(req, res, () => {
    updateClaims(req.query.uid).then(() => {
      res.status(200).send('success')
    }).catch((error) => {
      console.error('REFRESH ERROR', error)
      res.status(400).send(error)
    })
  })
})