http-proxy-middleware/README.md

# http-proxy-middleware
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Node.js proxying made simple. Configure proxy middleware with ease for [connect](https://github.com/senchalabs/connect), [express](https://github.com/strongloop/express), [browser-sync](https://github.com/BrowserSync/browser-sync) and [many more](#compatible-servers).
Powered by the popular Nodejitsu [`http-proxy`](https://github.com/nodejitsu/node-http-proxy). [![GitHub stars](https://img.shields.io/github/stars/nodejitsu/node-http-proxy.svg?style=social&label=Star)](https://github.com/nodejitsu/node-http-proxy)
## TL;DR
Proxy `/api` requests to `http://www.example.org`
```javascript
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](https://github.com/nodejitsu/node-http-proxy#options) can be used, along with some extra `http-proxy-middleware` [options](#options).
:bulb: **Tip:** Set the option `changeOrigin` to `true` for [name-based virtual hosted sites](http://en.wikipedia.org/wiki/Virtual_hosting#Name-based).
## Table of Contents
<!-- MarkdownTOC autolink=true bracket=round depth=2 -->
- [Install](#install)
- [Core concept](#core-concept)
- [Example](#example)
- [Context matching](#context-matching)
- [Options](#options)
    - [http-proxy-middleware options](#http-proxy-middleware-options)
    - [http-proxy events](#http-proxy-events)
    - [http-proxy options](#http-proxy-options)
- [Shorthand](#shorthand)
    - [app.use\(path, proxy\)](#appusepath-proxy)
- [WebSocket](#websocket)
    - [External WebSocket upgrade](#external-websocket-upgrade)
- [Working examples](#working-examples)
- [Recipes](#recipes)
- [Compatible servers](#compatible-servers)
- [Tests](#tests)
- [Changelog](#changelog)
- [License](#license)
<!-- /MarkdownTOC -->
## Install
```javascript
$ npm install --save-dev http-proxy-middleware
```
## Core concept
Proxy middleware configuration.
#### proxy([context,] config)
```javascript
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](#context-matching))
* **options.target**: target host to proxy to. _(protocol + host)_
(full list of [`http-proxy-middleware` configuration options](#options))
#### proxy(uri [, config])
``` javascript
// shorthand syntax for the example above:
var apiProxy = proxy('http://www.example.org/api');
```
More about the [shorthand configuration](#shorthand).
## Example
An example with `express` server.
```javascript
// 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](http://expressjs.com/en/4x/api.html#app.use) to mount the proxy or when you need more flexibility.
The [RFC 3986 `path`](https://tools.ietf.org/html/rfc3986#section-3.3) 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](https://www.npmjs.com/package/micromatch) or [glob](https://www.npmjs.com/package/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.
    ```javascript
    /**
     * @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.
    ```javascript
    // 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.
    ```javascript
    // 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`.
    ```javascript
    // simple replace
    function logProvider(provider) {
        // replace the default console log provider.
        return require('winston');
    }
    ```
    ```javascript
    // 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](https://github.com/nodejitsu/node-http-proxy#listening-for-proxy-events):
*  **option.onError**: function, subscribe to http-proxy's `error` event for custom error handling.
    ```javascript
    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.
    ```javascript
    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.
    ```javascript
    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.
    ```javascript
    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.
    ```javascript
    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.
    ```javascript
    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](https://github.com/nodejitsu/node-http-proxy#options) 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](http://nodejs.org/api/https.html#https_class_https_agent) and [http agent](http://nodejs.org/api/http.html#http_class_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](https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Request_fields). (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.
```javascript
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:
```javascript
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
```javascript
// 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.
```javascript
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](https://github.com/chimurai/http-proxy-middleware/tree/master/examples).
* Browser-Sync ([example source](https://github.com/chimurai/http-proxy-middleware/tree/master/examples/browser-sync/index.js))
* express ([example source](https://github.com/chimurai/http-proxy-middleware/tree/master/examples/express/index.js))
* connect ([example source](https://github.com/chimurai/http-proxy-middleware/tree/master/examples/connect/index.js))
* WebSocket ([example source](https://github.com/chimurai/http-proxy-middleware/tree/master/examples/websocket/index.js))
## Recipes
View the [recipes](https://github.com/chimurai/http-proxy-middleware/tree/master/recipes) for common use cases.
## Compatible servers
`http-proxy-middleware` is compatible with the following servers:
* [connect](https://www.npmjs.com/package/connect)
* [express](https://www.npmjs.com/package/express)
* [browser-sync](https://www.npmjs.com/package/browser-sync)
* [lite-server](https://www.npmjs.com/package/lite-server)
* [grunt-contrib-connect](https://www.npmjs.com/package/grunt-contrib-connect)
* [grunt-browser-sync](https://www.npmjs.com/package/grunt-browser-sync)
* [gulp-connect](https://www.npmjs.com/package/gulp-connect)
* [gulp-webserver](https://www.npmjs.com/package/gulp-webserver)
Sample implementations can be found in the [server recipes](https://github.com/chimurai/http-proxy-middleware/tree/master/recipes/servers.md).
## Tests
Run the test suite:
```bash
# install dependencies
$ npm install
```
unit testing
```bash
# unit tests
$ npm test
```
coverage
```bash
# code coverage
$ npm run cover
```
## Changelog
- [View changelog](https://github.com/chimurai/http-proxy-middleware/blob/master/CHANGELOG.md)
## License
The MIT License (MIT)
Copyright (c) 2015-2017 Steven Chim