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node-http-proxy

node-http-proxy is an HTTP programmable proxying library that supports websockets. It is suitable for implementing components such as proxies and load balancers.

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Core Concept

A new proxy is created by calling createProxyServer and passing an options object as argument (valid properties are available here)

var httpProxy = require('http-proxy');

var proxy = httpProxy.createProxyServer(options);

An object will be returned with four values:

  • web req, res, [options] (used for proxying regular HTTP(S) requests)
  • ws req, socket, head, [options] (used for proxying WS(S) requests)
  • listen port (a function that wraps the object in a webserver, for your convenience)
  • close [callback] (a function that closes the inner webserver and stops listening on given port)

It is then possible to proxy requests by calling these functions

http.createServer(function(req, res) {
  proxy.web(req, res, { target: 'http://mytarget.com:8080' });
});

Errors can be listened on either using the Event Emitter API

proxy.on('error', function(e) {
  ...
});

or using the callback API

proxy.web(req, res, { target: 'http://mytarget.com:8080' }, function(e) { ... });

When a request is proxied it follows two different pipelines (available here) which apply transformations to both the req and res object. The first pipeline (ingoing) is responsible for the creation and manipulation of the stream that connects your client to the target. The second pipeline (outgoing) is responsible for the creation and manipulation of the stream that, from your target, returns data to the client.

Setup a basic stand-alone proxy server

var http = require('http'),
    httpProxy = require('http-proxy');
//
// Create your proxy server and set the target in the options.
//
httpProxy.createProxyServer({target:'http://localhost:9000'}).listen(8000);

//
// Create your target server
//
http.createServer(function (req, res) {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.write('request successfully proxied!' + '\n' + JSON.stringify(req.headers, true, 2));
  res.end();
}).listen(9000);

Setup a stand-alone proxy server with custom server logic

This example show how you can proxy a request using your own HTTP server and also you can put your own logic to handle the request.

var http = require('http'),
    httpProxy = require('http-proxy');

//
// Create a proxy server with custom application logic
//
var proxy = httpProxy.createProxyServer({});

//
// Create your custom server and just call `proxy.web()` to proxy
// a web request to the target passed in the options
// also you can use `proxy.ws()` to proxy a websockets request
//
var server = http.createServer(function(req, res) {
  // You can define here your custom logic to handle the request
  // and then proxy the request.
  proxy.web(req, res, { target: 'http://127.0.0.1:5060' });
});

console.log("listening on port 5050")
server.listen(5050);

Modify a response from a proxied server

Sometimes when you have received a HTML/XML document from the server of origin you would like to modify it before forwarding it on.

Harmon allows you to do this in a streaming style so as to keep the pressure on the proxy to a minimum.

Setup a stand-alone proxy server with proxy request header re-writing

This example shows how you can proxy a request using your own HTTP server that modifies the outgoing proxy request by adding a special header.

var http = require('http'),
    httpProxy = require('http-proxy');

//
// Create a proxy server with custom application logic
//
var proxy = httpProxy.createProxyServer({});

// To modify the proxy connection before data is sent, you can listen
// for the 'proxyReq' event. When the event is fired, you will receive
// the following arguments:
// (http.ClientRequest proxyReq, http.IncomingMessage req,
//  http.ServerResponse res, Object options). This mechanism is useful when
// you need to modify the proxy request before the proxy connection
// is made to the target.
//
proxy.on('proxyReq', function(proxyReq, req, res, options) {
  proxyReq.setHeader('X-Special-Proxy-Header', 'foobar');
});

var server = http.createServer(function(req, res) {
  // You can define here your custom logic to handle the request
  // and then proxy the request.
  proxy.web(req, res, {
    target: 'http://127.0.0.1:5060'
  });
});

console.log("listening on port 5050")
server.listen(5050);

Setup a stand-alone proxy server with latency

var http = require('http'),
    httpProxy = require('http-proxy');

//
// Create a proxy server with latency
//
var proxy = httpProxy.createProxyServer();

//
// Create your server that makes an operation that waits a while
// and then proxies the request
//
http.createServer(function (req, res) {
  // This simulates an operation that takes 500ms to execute
  setTimeout(function () {
    proxy.web(req, res, {
      target: 'http://localhost:9008'
    });
  }, 500);
}).listen(8008);

//
// Create your target server
//
http.createServer(function (req, res) {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.write('request successfully proxied to: ' + req.url + '\n' + JSON.stringify(req.headers, true, 2));
  res.end();
}).listen(9008);

Listening for proxy events

  • error: The error event is emitted if the request to the target fail.
  • proxyRes: This event is emitted if the request to the target got a response.
  • open: This event is emitted once the proxy websocket was created and piped into the target websocket.
  • close: This event is emitted once the proxy websocket was closed.
  • (DEPRECATED) proxySocket: Deprecated in favor of open.
var httpProxy = require('http-proxy');
// Error example
//
// Http Proxy Server with bad target
//
var proxy = httpProxy.createServer({
  target:'http://localhost:9005'
});

proxy.listen(8005);

//
// Listen for the `error` event on `proxy`.
proxy.on('error', function (err, req, res) {
  res.writeHead(500, {
    'Content-Type': 'text/plain'
  });

  res.end('Something went wrong. And we are reporting a custom error message.');
});

//
// Listen for the `proxyRes` event on `proxy`.
//
proxy.on('proxyRes', function (proxyRes, req, res) {
  console.log('RAW Response from the target', JSON.stringify(proxyRes.headers, true, 2));
});

//
// Listen for the `open` event on `proxy`.
//
proxy.on('open', function (proxySocket) {
  // listen for messages coming FROM the target here
  proxySocket.on('data', hybiParseAndLogMessage);
});

//
// Listen for the `close` event on `proxy`.
//
proxy.on('close', function (req, socket, head) {
  // view disconnected websocket connections
  console.log('Client disconnected');
});

Using HTTPS

You can activate the validation of a secure SSL certificate to the target connection (avoid self signed certs), just set secure: true in the options.

HTTPS -> HTTP
//
// Create the HTTPS proxy server in front of a HTTP server
//
httpProxy.createServer({
  target: {
    host: 'localhost',
    port: 9009
  },
  ssl: {
    key: fs.readFileSync('valid-ssl-key.pem', 'utf8'),
    cert: fs.readFileSync('valid-ssl-cert.pem', 'utf8')
  }
}).listen(8009);
HTTPS -> HTTPS
//
// Create the proxy server listening on port 443
//
httpProxy.createServer({
  ssl: {
    key: fs.readFileSync('valid-ssl-key.pem', 'utf8'),
    cert: fs.readFileSync('valid-ssl-cert.pem', 'utf8')
  },
  target: 'https://localhost:9010',
  secure: true // Depends on your needs, could be false.
}).listen(443);

Proxying WebSockets

You can activate the websocket support for the proxy using ws:true in the options.

//
// Create a proxy server for websockets
//
httpProxy.createServer({
  target: 'ws://localhost:9014',
  ws: true
}).listen(8014);

Also you can proxy the websocket requests just calling the ws(req, socket, head) method.

//
// Setup our server to proxy standard HTTP requests
//
var proxy = new httpProxy.createProxyServer({
  target: {
    host: 'localhost',
    port: 9015
  }
});
var proxyServer = http.createServer(function (req, res) {
  proxy.web(req, res);
});

//
// Listen to the `upgrade` event and proxy the
// WebSocket requests as well.
//
proxyServer.on('upgrade', function (req, socket, head) {
  proxy.ws(req, socket, head);
});

proxyServer.listen(8015);

Contributing and Issues

  • Search on Google/Github
  • If you can't find anything, open an issue
  • If you feel comfortable about fixing the issue, fork the repo
  • Commit to your local branch (which must be different from master)
  • Submit your Pull Request (be sure to include tests and update documentation)

Options

httpProxy.createProxyServer supports the following options:

  • target: url string to be parsed with the url module
  • forward: url string to be parsed with the url module
  • agent: object to be passed to http(s).request (see Node's https agent and http agent objects)
  • secure: true/false, if you want to verify the SSL Certs
  • xfwd: true/false, adds x-forward headers
  • toProxy: passes the absolute URL as the path (useful for proxying to proxies)
  • hostRewrite: rewrites the location hostname on (301/302/307/308) redirects.

If you are using the proxyServer.listen method, the following options are also applicable:

  • ssl: object to be passed to https.createServer()
  • ws: true/false, if you want to proxy websockets

Shutdown

  • When testing or running server within another program it may be necessary to close the proxy.
  • This will stop the proxy from accepting new connections.
var proxy = new httpProxy.createProxyServer({
  target: {
    host: 'localhost',
    port: 1337
  }
});

proxy.close();

Test

$ npm test

Logo

Logo created by Diego Pasquali

License

The MIT License (MIT)

Copyright (c) 2010 - 2013 Nodejitsu Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.