Firebase Hosting with dynamic cloud functions rewrites

Question

I have an express.js based cloud functions app on firebase in a function named api. To use a custom domain, I\'m trying to use Firebase Hosting rewrites to rout

Answer 1

You can use a single Firebase hosting rewrite rule with a complementing rewrite middleware in Express.

1. Add a rewrite in your firebase.json file.

   {
     "source": "/api/**",
     "function": "api"
   }
   

2. Include an app.use() middleware to rewrite the request url.

   const functions = require('firebase-functions');
   const express = require('express');
   
   const API_PREFIX = 'api';
   const app = express();
   
   // Rewrite Firebase hosting requests: /api/:path => /:path
   app.use((req, res, next) => {
       if (req.url.indexOf(`/${API_PREFIX}/`) === 0) {
           req.url = req.url.substring(API_PREFIX.length + 1);
       }
       next();
   });
   
   app.get('/users/:userId/:userData/json', (req, res) => {
       // Do App stuff here
   });
   
   exports[API_PREFIX] = functions.https.onRequest(app);