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http-proxy-middleware

http-proxy-middleware

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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. GitHub stars

TL;DR

Proxy /api requests to http://www.example.org

var express = require('express');
var proxy = require('http-proxy-middleware');
 
var app = express();
 
app.use('/api', proxy({target: 'http://www.example.org', changeOrigin: true}));
app.listen(3000);
 
// http://localhost:3000/api/foo/bar -> http://www.example.org/api/foo/bar 

All http-proxy options can be used, along with some extra http-proxy-middleware options.

💡 Tip: Set the option changeOrigin to true for name-based virtual hosted sites.

Table of Contents

Install

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

Core concept

Proxy middleware configuration.

proxy([context,] config)

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: Determine which requests should be proxied to the target host. (more on context matching)
  • options.target: target host to proxy to. (protocol + host)

(full list of http-proxy-middleware configuration options)

proxy(uri [, config])

// 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');
 
// proxy middleware options 
var options = {
        target: 'http://www.example.org', // target host 
        changeOrigin: true,               // needed for virtual hosted sites 
        ws: true,                         // proxy websockets 
        pathRewrite: {
            '^/api/old-path' : '/api/new-path',     // rewrite path 
            '^/api/remove/path' : '/path'           // remove base path 
        },
        router: {
            // 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 (without context) 
var exampleProxy = proxy(options);
 
// mount `exampleProxy` in web server 
var app = express();
    app.use('/api', exampleProxy);
    app.listen(3000);

Context matching

Providing an alternative way to decide which requests should be proxied; In case you are not able to use the server's path parameter to mount the proxy or when you need more flexibility.

The RFC 3986 path is be used for context matching.

         foo://example.com:8042/over/there?name=ferret#nose
         \_/   \______________/\_________/ \_________/ \__/
          |           |            |            |        |
       scheme     authority       path        query   fragment
  • path matching

    • proxy({...}) - matches any path, all requests will be proxied.
    • proxy('/', {...}) - matches any path, all requests will be proxied.
    • proxy('/api', {...}) - matches paths starting with /api
  • multiple path matching

    • proxy(['/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.

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

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

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

Options

http-proxy-middleware options

  • option.pathRewrite: object/function, 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/'}
     
    // custom rewriting 
    pathRewrite: function (path, req) { return path.replace('/api', '/base/api') }
  • option.router: object/function, re-target option.target for specific requests.

    // Use `host` and/or `path` to match requests. First match will be used. 
    // The order of the configuration matters. 
    router: {
        '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 
    }
     
    // Custom router function 
    router: function(req) {
        return 'http://localhost:8004';
    }
  • 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;
    }
  • (DEPRECATED) option.proxyHost: Use option.changeOrigin = true instead.

  • (DEPRECATED) option.proxyTable: Use option.router instead.

http-proxy 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');
    }

http-proxy options

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

  • 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 (note: you will have to append / manually if required).
  • option.localAddress : Local interface string to bind for outgoing connections
  • option.changeOrigin: true/false, Default: false - changes the origin of the host header to the target URL
  • 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.cookieDomainRewrite: rewrites domain of set-cookie headers. Possible values:
    • false (default): disable cookie rewriting
    • String: new domain, for example cookieDomainRewrite: "new.domain". To remove the domain, use cookieDomainRewrite: "".
    • Object: mapping of domains to new domains, use "*" to match all domains.
      For example keep one domain unchanged, rewrite one domain and remove other domains:
      cookieDomainRewrite: {
        "unchanged.domain": "unchanged.domain",
        "old.domain": "new.domain",
        "*": ""
      }
  • option.headers: object, adds request headers. (Example: {host:'www.example.org'})
  • option.proxyTimeout: timeout (in millis) when proxy receives no response from target

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:

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' 

Working examples

View and play around with working examples.

Recipes

View the recipes for common use cases.

Compatible servers

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

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

License

The MIT License (MIT)

Copyright (c) 2015-2017 Steven Chim