firebasecustomTokenClient

customTokenClientSide.js

import firebase from 'firebase/app'
import axios from 'axios'
require('firebase/auth')
const YOUR_BACKEND_PATH = 'https://mylambdaapigatewayendpoint.com/auth'

const config = {
  apiKey: process.env['FIREBASE_API_KEY'],
  authDomain: process.env['FIREBASE_AUTH_DOMAIN'],
  databaseURL: process.env['FIREBASE_DATABASE_URL'],
  projectId: process.env['FIREBASE_PROJECT'],
  storageBucket: process.env['FIREBASE_STORAGE'],
  messagingSenderId: process.env['FIREBASE_MESSAGE_ID'],
}

firebase.initializeApp(config)

const withAuthHeader = () => {
  const token = localStorage.getItem('id_token') // Whereever you are storaging your auth0 token
  const instance = axios.create({
    headers: {
      'Authorization': `Bearer ${token}`,
      'Content-Type': 'application/json',
    },
  })
  return instance
}

const setCustomToken = () => {
  const axios = withAuthHeader()
  const { data } = await axios.post(YOUR_BACKEND_PATH)
  const firebaseToken = await firebase.auth().signInWithCustomToken(data.token)
  return firebaseToken
}