Latency proxy

Delayed reqest example

$ time curl -XGET localhost:8008
{
  "status" : 200,
  "name" : "X-Ray",
  "version" : {
    "number" : "1.3.5",
    "build_hash" : "4a50e7df768fddd572f48830ae9c35e4ded86ac1",
    "build_timestamp" : "2014-11-05T15:21:28Z",
    "build_snapshot" : false,
    "lucene_version" : "4.9"
  },
  "tagline" : "You Know, for Search"
}

real	0m10.048s
user	0m0.004s
sys	0m0.004s

package.json

{
  "name": "latency-proxy",
  "version": "0.0.1",
  "main": "proxy.js",
  "author": "Igor Kupczyński <igor@kupczynski.info>",
  "license": "Apache 2.0",
  "dependencies": {
    "http-proxy": "^1.8.1",
    "optimist": "^0.6.1"
  }
}

proxy.js

'use strict';
// Opts parsing
const argv = require('optimist')
          .demand(['server','latency'])
          .usage('Usage: $0 --server [address] --latency [num]')
          .describe('server', 'Server to proxy to, e.g. http://localhost:9200')
          .describe('latency', 'How much time will each request be on hold before proxing to the server (in seconds)')
          .describe('proxy_port', 'Port that the proxy will listen on').default('proxy_port', 8008)
          .argv,
      proxy_host = 'localhost',
      proxy_port = argv.proxy_port,
      proxy_to = argv.server,
      latency = argv.latency;

// Modules
const http = require('http'),
      httpProxy = require('http-proxy'),
      sec = 1000;

// Proxy definition
const proxy = httpProxy.createProxyServer({}),
      proxy_func = function(req, res, target) {
          return function() {
              proxy.web(req, res, {target: target});
          };
      };

// Listen to requests
http.createServer(function (req, res) {
    // Run the proxy logic on each request after a timeoue
    setTimeout(proxy_func(req, res, proxy_to), latency * sec);
}).listen(proxy_port, function(e) {
    console.log("Listening at 'localhost:" + proxy_port + "', proxying to '" + proxy_to +
                "', each request is on hold for " + latency + "s");
});

Running the proxy

$ node --harmony proxy.js --server http://localhost:9200 --latency 10
Listening at 'localhost:8008', proxying to 'http://localhost:9200', each request is on hold for 10s