Node.js: Proxy multipart/form-data file upload to application/octet-stream REST API call

server.js

#!/usr/bin/env node

// dependencies
const https = require('https');
const express = require('express');
const multer = require('multer');

// app
const app = express();
const storage = multer.memoryStorage();
const upload = multer({storage: storage});

// form
app.get('/', (req, res) => {
  res.header('Content-Type', 'text/html');
  res.status(200).send(
`<form method="post" enctype="multipart/form-data">
  <input type="file" name="image">
  <input type="submit" value="Upload">
</form>`
  );
});

// upload
app.post('/', upload.single('image'), (req, res) => {

  let options = {
    host: 'upload.api.com',
    method: 'POST',
    path: '/upload',
    headers: {
      'Authorization': 'Bearer my-access-token',
      'Content-Type': 'application/octet-stream',
      'Content-Length': req.file.buffer.length
    }
  };

  const request = https.request(options, response => {
    // NOTE: rewrite headers if needed
    res.writeHead(response.statusCode, response.headers);
    response.pipe(res);
  });

  request.write(req.file.buffer);
  request.end();

});

// start server
let port = process.env.PORT || 4000;
app.listen(port, () => {
  console.log(`Upload API listening on port ${port}`);
});