Debugging Proxy Server to host a subset of production resources locally for troubleshooting.

interceptingProxyServer.js

// NOTE Before Starting, be sure you have an entry in your hosts file like:
// 127.0.0.1    domain.you.are.intercepting.com

'use strict';

var _         = require('lodash');
var express   = require('express');
var fs        = require('fs');
var httpProxy = require('http-proxy');
var https     = require('https');

module.exports = {

  /**
    * listen
    * Starts the CDN listening on a port.
    * @param options.port {Number}
    * @param options.sslPort {Number}
    * @param options.originHost {String} Hostname to proxy as
    * @param options.originIP {String} IP Address to proxy through to
    */
  listen: function (options) {
    options = _.extend({
      port: 80,
      sslPort: 443,
      originHost: "localhost",
      originIP: "127.0.0.1"
    }, options);

    // NOTE: Generate Self-Signed certificate and reference here. When you start debugging,
    //       be sure to hit the URL once directly first to accept the security warning, or
    //       the browser will silently block the insecure request.
    var sslOptions = {
      key: fs.readFileSync(__dirname +  "config/keys/cert.key"),
      cert: fs.readFileSync(__dirname + "config/keys/cert.crt")
    };

    var app = express();
    var proxy = httpProxy.createProxyServer();
    
    proxy.on('proxyReq', function(proxyReq) {
      console.log("Running intercepting proxy for " + options.originHost);
        proxyReq.setHeader('host', options.originHost);
        ipAddressUrl = "http://72.21.91.8";
      }
    });
    
    // NOTE Update this path to the path you want re-written for debugging. You'll
    //      be serving your local files instead here.
    app.use('/path/to/debugging', express.static(__dirname));

    // NOTE Everything else should be proxied through to the original host and returned
    //      normally.
    app.use(function (req, res, next) {
      proxy.web(req, res, {
        target: options.originIP,
        changeOrigin: true,
      });
    });

    app.listen(options.port);
    https.createServer(sslOptions, app).listen(options.sslPort);
  }
};