Users in China could not access app which backend is in Firebase, so we use CloudFlare redirects requests which sent from use in China.

• In CloudFlare site panel, enable workers
• In workers code editor:

addEventListener('fetch', event => {
  if(event.request.url.indexOf('firebase-storage')>=0){
    event.respondWith(
    fetch(event.request.url.replace('firebase-storage.XXXXXXXX.com','firebasestorage.googleapis.com'), event.request)
    )
  } else if(event.request.url.indexOf('firebase-db')>=0){
<!-- more -->

    event.respondWith(
    fetch(event.request.url.replace('firebase-db.XXXXXXXX.com','X-X-X.firebaseio.com'), event.request)
    )
  }
})
 

• In code editor, click Routes tab, add routing rules for this codes.