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.

TL;DR

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

varexpress=require('express');varproxy=require('http-proxy-middleware');varapp=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

Allhttp-proxyoptions can be used, along with some extra http-proxy-middlewareoptions.

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

Table of Contents

• Install
• Core concept
• Example
• Context matching
• Options
  • http-proxy-middleware options
  • http-proxy events
  • http-proxy options
• Shorthand
  • app.use(path, proxy)
• WebSocket
  • External WebSocket upgrade
• Working examples
• Recipes
• Compatible servers
• Tests
• Changelog
• License

Install

$npminstall--save-devhttp-proxy-middleware

Core concept

Proxy middleware configuration.

proxy([context,] config)

varproxy=require('http-proxy-middleware');varapiProxy=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:varapiProxy=proxy('http://www.example.org/api');

More about the shorthand configuration.

Example

An example with express server.

// include dependenciesvarexpress=require('express');varproxy=require('http-proxy-middleware');// proxy middleware optionsvaroptions={target: 'http://www.example.org',// target hostchangeOrigin: true,// needed for virtual hosted sitesws: true,// proxy websocketspathRewrite: {'^/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)varexampleProxy=proxy(options);// mount `exampleProxy` in web servervarapp=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} */varfilter=function(pathname,req){return(pathname.match('^/api')&&req.method==='GET');};varapiProxy=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){returnpath.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 replacefunctionlogProvider(provider){// replace the default console log provider.returnrequire('winston');}

  // verbose replacementfunctionlogProvider(provider){varlogger=new(require('winston').Logger)();varmyCustomProvider={log: logger.log,debug: logger.debug,info: logger.info,warn: logger.warn,error: logger.error}returnmyCustomProvider;}

• (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.

  functiononError(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.

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

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

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

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

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

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

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

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

  functiononClose(res,socket,head){// view disconnected websocket connectionsconsole.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.usepath 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 apiproxy('/',{target:'http://echo.websocket.org',ws:true});// shorthandproxy('http://echo.websocket.org',{ws:true});// shorter shorthandproxy('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.

varwsProxy=proxy('ws://echo.websocket.org',{changeOrigin:true});varapp=express();app.use(wsProxy);varserver=app.listen(3000);server.on('upgrade',wsProxy.upgrade);// <-- subscribe to http 'upgrade'

Working examples

View and play around with working examples.

• Browser-Sync (example source)
• express (example source)
• connect (example source)
• WebSocket (example 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
# linting
$ npm run lint
# unit tests
$ npm test# code coverage
$ npm run cover

Changelog

• View changelog

License

The MIT License (MIT)

Copyright (c) 2015-2017 Steven Chim