Convert application/octet-stream upload to ReadableStream

server.ts

import * as stream from "stream";
import * as express from "express";
import * as bodyParser from "body-parser";

const app = express();

app.use(bodyParser.raw());
app.use(bodyParser.json());

app.post("/upload", (req: express.Request, res: express.Response, next: express.NextFunction) => {
  const buffer = <Buffer>(<any>req).body;
  const passthroughStream = new stream.PassThrough();
  passthroughStream.end(buffer);

  // passthroughStream == readable stream with uploaded file data

  return res.send("Thanks");
});

app.listen(5000, () => {
  console.log("## Listening...");
});