curl.txt

curl -XPOST http://localhost:5000/test/post/proxy -H "content-type: application/json;charset=UTF-8" -d '{"dum":"dum"}'

package.json

{
  "name": "proxy",
  "version": "0.1.0",
  "description": "proxy",
  "main": "server.js",
  "repository": "",
  "keywords": [
    "proxy"
  ],
  "author": "Pulkit Singhal",
  "license": "Apache",
  "readmeFilename": "README.md",
  "dependencies": {
    "http-proxy": "1.1.2",
    "express": "4.1.1",
    "body-parser": "1.0.2",
    "connect-restreamer": "1.0.0"
  }
}

server.js

var http = require('http')
  , httpProxy = require('http-proxy')
  , express = require('express')
  , bodyParser = require('body-parser');

var proxy = httpProxy.createProxyServer({});

var app = express();
app.use(bodyParser());
app.use(require('connect-restreamer')());

app.all('/test/post/proxy',  function (req, res) {
  console.log('/test/post/proxy \n matched \t' + req.url);
  req.url = '/dummy';
  console.log(' re-routing \t' + req.url);

  var substituteBodyWithThis = {
    "a": {
      "b": {
        "c": []
      }
    }
  };

  console.log('before change: ' + req.body);
  req.body = JSON.stringify(substituteBodyWithThis);
  console.log('after change: ' + req.body);

  proxy.web(req, res, { target: 'http://localhost:9000' });
});


var port = Number(process.env.PORT || 5000);
app.listen(port, function() {
  console.log("Listening on " + port);
});

http.createServer(function (req, res) {
  if (req.method == 'POST') {
    console.log('1');
    var body = '';
    req.on('data', function (data) {
      console.log('2');
      body += data;
    });
    req.on('end', function () {
      console.log('3');
      console.log('request successfully proxied!' + '\n' + JSON.stringify(req.headers, true, 2) + '\n' + body);
      res.writeHead(200, { 'Content-Type': 'text/plain' });
      res.write('request successfully proxied!' + '\n' + JSON.stringify(req.headers, true, 2) + '\n' + body);
      res.end();
    });
    req.on('error', function(e) {
      console.log('problem with request: ' + e.message);
    });
    console.log('4');
  }
  console.log('5');
}).listen(9000);