Marketcloud/http-proxy-middleware

:zap: The one-liner node.js http-proxy middleware for connect, express and browser-sync

http-proxy-middleware

Node.js proxying made simple. Configure proxy middleware with ease for connect, express, browser-sync and many more.

Powered by the popular Nodejitsu http-proxy.

Table of Contents

• Install
• Core concept
• Example
• Context matching
• Shorthand
• WebSocket
• Options
• Working examples
• Recipes
• Compatible servers
• Tests
• Changelog
• License

Install

$ npm install --save-dev http-proxy-middleware

Core concept

Configure the proxy middleware.

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

var apiProxy = proxy('/api', {target: 'http://www.example.org'});
//                   \____/   \_____________________________/
//                     |                    |
//                   context             options

// 'apiProxy' is now ready to be used as middleware in a server.

• context: matches provided context against request-urls' path. Matching requests will be proxied to the target host. Example: '/api' or ['/api', '/ajax']. (more about context matching)
• options.target: target host to proxy to. (full list of proxy middleware options)

// shorthand syntax for the example above:
var apiProxy = proxy('http://www.example.org/api');

More about the shorthand configuration.

Example

An example with express server.

// include dependencies
var express = require('express');
var proxy = require('http-proxy-middleware');

// configure proxy middleware context
var context = '/api';                     // requests with this path will be proxied
                                          // use Array for multipath: ['/api', '/rest']

// configure proxy middleware options
var options = {
        target: 'http://www.example.org', // target host
        changeOrigin: true,               // needed for virtual hosted sites
        ws: true,                         // proxy websockets
        pathRewrite: {
            '^/old/api' : '/new/api',     // rewrite path
            '^/remove/api' : '/api'       // remove path
        },
        proxyTable: {
            // when request.headers.host == 'dev.localhost:3000',
            // override target 'http://www.example.org' to 'http://localhost:8000'
            'dev.localhost:3000' : 'http://localhost:8000'
        }
    };

// create the proxy
var apiProxy = proxy(context, options);

// use the configured `apiProxy` in web server
var app = express();
    app.use(apiProxy);
    app.listen(3000);

Tip: For name-based virtual hosted sites, you'll need to use the option changeOrigin and set it to true.

Context matching

http-proxy-middleware offers several ways to decide which requests should be proxied. Request URL's path-absolute and query will be used for context matching .

• path matching

  • '/' - matches any path, all requests will be proxied.
  • '/api' - matches paths starting with /api

• multiple path matching

  • ['/api', '/ajax', '/someotherpath']

• wildcard path matching

  For fine-grained control you can use wildcard matching. Glob pattern matching is done by micromatch. Visit micromatch or glob for more globbing examples.

  • '**' matches any path, all requests will be proxied.
  • '**/*.html' matches any path which ends with .html
  • '/*.html' matches paths directly under path-absolute
  • '/api/**/*.html' matches requests ending with .html in the path of /api
  • ['/api/**', '/ajax/**'] combine multiple patterns
  • ['/api/**', '!**/bad.json'] exclusion

• custom matching

  For full control you can provide a custom filter function to determine which requests should be proxied or not.

  var filter = function (path, req) {
      return (path.match('^/api') && req.method === 'GET');
  };
  
  var apiProxy = proxy(filter, {target: 'http://www.example.org'})

Shorthand

Use the shorthand syntax when verbose configuration is not needed. The context and option.target will be automatically configured when shorthand is used. Options can still be used if needed.

proxy('http://www.example.org:8000/api');
// proxy('/api', {target: 'http://www.example.org:8000'});


proxy('http://www.example.org:8000/api/books/*/**.json');
// proxy('/api/books/*/**.json', {target: 'http://www.example.org:8000'});


proxy('http://www.example.org:8000/api', {changeOrigin:true});
// proxy('/api', {target: 'http://www.example.org:8000', changeOrigin: true});

app.use(path, proxy)

If you want to use the server's app.use path parameter to match requests;

Create and mount the proxy without the http-proxy-middleware context parameter:

app.use('/api', proxy({target:'http://www.example.org', changeOrigin:true}));

app.use documentation:

• express: http://expressjs.com/en/4x/api.html#app.use
• connect: https://github.com/senchalabs/connect#mount-middleware

WebSocket

// verbose api
proxy('/', {target:'http://echo.websocket.org', ws:true});

// shorthand
proxy('http://echo.websocket.org', {ws:true});

// shorter shorthand
proxy('ws://echo.websocket.org');

External WebSocket upgrade

In the previous WebSocket examples, http-proxy-middleware relies on a initial http request in order to listen to the http upgrade event. If you need to proxy WebSockets without the initial http request, you can subscribe to the server's http upgrade event manually.

var wsProxy = proxy('ws://echo.websocket.org', {changeOrigin:true});

var app = express();
    app.use(wsProxy);

var server = app.listen(3000);
    server.on('upgrade', wsProxy.upgrade);  // <-- subscribe to http 'upgrade'

Options

• option.pathRewrite: object, rewrite target's url path. Object-keys will be used as RegExp to match paths.

  // rewrite path
  pathRewrite: {"^/old/api" : "/new/api"}
  
  // remove path
  pathRewrite: {"^/remove/api" : ""}
  
  // add base path
  pathRewrite: {"^/" : "/basepath/"}

• option.proxyTable: object, re-target option.target based on the request header host parameter. host can be used in conjunction with path. Only one instance of the proxy will be used. The order of the configuration matters.

  proxyTable: {
      "integration.localhost:3000" : "http://localhost:8001",  // host only
      "staging.localhost:3000"     : "http://localhost:8002",  // host only
      "localhost:3000/api"         : "http://localhost:8003",  // host + path
      "/rest"                      : "http://localhost:8004"   // path only
  }

• option.logLevel: string, ['debug', 'info', 'warn', 'error', 'silent']. Default: 'info'

• option.logProvider: function, modify or replace log provider. Default: console.

  // simple replace
  function logProvider(provider) {
      // replace the default console log provider.
      return require('winston');
  }

  // verbose replacement
  function logProvider(provider) {
      var logger = new (require('winston').Logger)();
  
      var myCustomProvider = {
          log: logger.log,
          debug: logger.debug,
          info: logger.info,
          warn: logger.warn,
          error: logger.error
      }
      return myCustomProvider;
  }

Events

Subscribe to http-proxy events:

• option.onError: function, subscribe to http-proxy's error event for custom error handling.

  function onError(err, req, res) {
      res.writeHead(500, {
          'Content-Type': 'text/plain'
      });
      res.end('Something went wrong. And we are reporting a custom error message.');
  }

• option.onProxyRes: function, subscribe to http-proxy's proxyRes event.

  function onProxyRes(proxyRes, req, res) {
      proxyRes.headers['x-added'] = 'foobar';     // add new header to response
      delete proxyRes.headers['x-removed'];       // remove header from response
  }

• option.onProxyReq: function, subscribe to http-proxy's proxyReq event.

  function onProxyReq(proxyReq, req, res) {
      // add custom header to request
      proxyReq.setHeader('x-added', 'foobar');
      // or log the req
  }

• option.onProxyReqWs: function, subscribe to http-proxy's proxyReqWs event.

  function onProxyReqWs(proxyReq, req, socket, options, head) {
      // add custom header
      proxyReq.setHeader('X-Special-Proxy-Header', 'foobar');
  }

• option.onOpen: function, subscribe to http-proxy's open event.

  function onOpen(proxySocket) {
      // listen for messages coming FROM the target here
      proxySocket.on('data', hybiParseAndLogMessage);
  }

• option.onClose: function, subscribe to http-proxy's close event.

  function onClose(res, socket, head) {
      // view disconnected websocket connections
      console.log('Client disconnected');
  }

• (DEPRECATED) option.proxyHost: Use option.changeOrigin = true instead.

http-proxy options

The following options are provided by the underlying http-proxy.

• option.target: url string to be parsed with the url module
• option.forward: url string to be parsed with the url module
• option.agent: object to be passed to http(s).request (see Node's https agent and http agent objects)
• option.ssl: object to be passed to https.createServer()
• option.ws: true/false: if you want to proxy websockets
• option.xfwd: true/false, adds x-forward headers
• option.secure: true/false, if you want to verify the SSL Certs
• option.toProxy: true/false, passes the absolute URL as the path (useful for proxying to proxies)
• option.prependPath: true/false, Default: true - specify whether you want to prepend the target's path to the proxy path>
• option.ignorePath: true/false, Default: false - specify whether you want to ignore the proxy path of the incoming request>
• option.localAddress : Local interface string to bind for outgoing connections
• option.changeOrigin: true/false, adds host to request header.
• option.auth : Basic authentication i.e. 'user:password' to compute an Authorization header.
• option.hostRewrite: rewrites the location hostname on (301/302/307/308) redirects.
• option.autoRewrite: rewrites the location host/port on (301/302/307/308) redirects based on requested host/port. Default: false.
• option.protocolRewrite: rewrites the location protocol on (301/302/307/308) redirects to 'http' or 'https'. Default: null.
• option.headers: object, adds request headers. (Example: {host:'www.example.org'})

Working examples

View and play around with working examples.

• Browser-Sync (exampe source)
• express (exampe source)
• connect (exampe source)
• WebSocket (exampe source)

Recipes

View the recipes for common use cases.

Compatible servers

http-proxy-middleware is compatible with the following servers:

• connect
• express
• browser-sync
• lite-server
• grunt-contrib-connect
• grunt-browser-sync
• gulp-connect
• gulp-webserver

Sample implementations can be found in the server recipes.

Tests

Run the test suite:

# install dependencies
$ npm install

unit testing

# unit tests
$ npm test

coverage

# code coverage
$ npm run cover

Changelog

• View changelog

License

The MIT License (MIT)

Copyright (c) 2015-2016 Steven Chim