599 lines
		
	
	
		
			22 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
			
		
		
	
	
			599 lines
		
	
	
		
			22 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
# http-proxy-middleware
 | 
						|
 | 
						|
[](https://github.com/chimurai/http-proxy-middleware/actions?query=branch%3Amaster)
 | 
						|
[](https://coveralls.io/r/chimurai/http-proxy-middleware)
 | 
						|
[](https://snyk.io/test/npm/http-proxy-middleware)
 | 
						|
[](https://www.npmjs.com/package/http-proxy-middleware)
 | 
						|
 | 
						|
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). [](https://github.com/nodejitsu/node-http-proxy)
 | 
						|
 | 
						|
## ⚠️ Note <!-- omit in toc -->
 | 
						|
 | 
						|
This page is showing documentation for version v2.x.x ([release notes](https://github.com/chimurai/http-proxy-middleware/releases))
 | 
						|
 | 
						|
If you're looking for v0.x documentation. Go to:
 | 
						|
https://github.com/chimurai/http-proxy-middleware/tree/v0.21.0#readme
 | 
						|
 | 
						|
## TL;DR <!-- omit in toc -->
 | 
						|
 | 
						|
Proxy `/api` requests to `http://www.example.org`
 | 
						|
 | 
						|
```javascript
 | 
						|
// javascript
 | 
						|
 | 
						|
const express = require('express');
 | 
						|
const { createProxyMiddleware } = require('http-proxy-middleware');
 | 
						|
 | 
						|
const app = express();
 | 
						|
 | 
						|
app.use('/api', createProxyMiddleware({ target: 'http://www.example.org', changeOrigin: true }));
 | 
						|
app.listen(3000);
 | 
						|
 | 
						|
// http://localhost:3000/api/foo/bar -> http://www.example.org/api/foo/bar
 | 
						|
```
 | 
						|
 | 
						|
```typescript
 | 
						|
// typescript
 | 
						|
 | 
						|
import * as express from 'express';
 | 
						|
import { createProxyMiddleware, Filter, Options, RequestHandler } from 'http-proxy-middleware';
 | 
						|
 | 
						|
const app = express();
 | 
						|
 | 
						|
app.use('/api', createProxyMiddleware({ 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 <!-- omit in toc -->
 | 
						|
 | 
						|
- [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)
 | 
						|
- [Intercept and manipulate requests](#intercept-and-manipulate-requests)
 | 
						|
- [Intercept and manipulate responses](#intercept-and-manipulate-responses)
 | 
						|
- [Working examples](#working-examples)
 | 
						|
- [Recipes](#recipes)
 | 
						|
- [Compatible servers](#compatible-servers)
 | 
						|
- [Tests](#tests)
 | 
						|
- [Changelog](#changelog)
 | 
						|
- [License](#license)
 | 
						|
 | 
						|
## Install
 | 
						|
 | 
						|
```bash
 | 
						|
$ npm install --save-dev http-proxy-middleware
 | 
						|
```
 | 
						|
 | 
						|
## Core concept
 | 
						|
 | 
						|
Proxy middleware configuration.
 | 
						|
 | 
						|
#### createProxyMiddleware([context,] config)
 | 
						|
 | 
						|
```javascript
 | 
						|
const { createProxyMiddleware } = require('http-proxy-middleware');
 | 
						|
 | 
						|
const apiProxy = createProxyMiddleware('/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))
 | 
						|
 | 
						|
#### createProxyMiddleware(uri [, config])
 | 
						|
 | 
						|
```javascript
 | 
						|
// shorthand syntax for the example above:
 | 
						|
const apiProxy = createProxyMiddleware('http://www.example.org/api');
 | 
						|
```
 | 
						|
 | 
						|
More about the [shorthand configuration](#shorthand).
 | 
						|
 | 
						|
## Example
 | 
						|
 | 
						|
An example with `express` server.
 | 
						|
 | 
						|
```javascript
 | 
						|
// include dependencies
 | 
						|
const express = require('express');
 | 
						|
const { createProxyMiddleware } = require('http-proxy-middleware');
 | 
						|
 | 
						|
// proxy middleware options
 | 
						|
/** @type {import('http-proxy-middleware/dist/types').Options} */
 | 
						|
const 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)
 | 
						|
const exampleProxy = createProxyMiddleware(options);
 | 
						|
 | 
						|
// mount `exampleProxy` in web server
 | 
						|
const 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.
 | 
						|
 | 
						|
[RFC 3986 `path`](https://tools.ietf.org/html/rfc3986#section-3.3) is used for context matching.
 | 
						|
 | 
						|
```ascii
 | 
						|
         foo://example.com:8042/over/there?name=ferret#nose
 | 
						|
         \_/   \______________/\_________/ \_________/ \__/
 | 
						|
          |           |            |            |        |
 | 
						|
       scheme     authority       path        query   fragment
 | 
						|
```
 | 
						|
 | 
						|
- **path matching**
 | 
						|
 | 
						|
  - `createProxyMiddleware({...})` - matches any path, all requests will be proxied.
 | 
						|
  - `createProxyMiddleware('/', {...})` - matches any path, all requests will be proxied.
 | 
						|
  - `createProxyMiddleware('/api', {...})` - matches paths starting with `/api`
 | 
						|
 | 
						|
- **multiple path matching**
 | 
						|
 | 
						|
  - `createProxyMiddleware(['/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.
 | 
						|
 | 
						|
  - `createProxyMiddleware('**', {...})` matches any path, all requests will be proxied.
 | 
						|
  - `createProxyMiddleware('**/*.html', {...})` matches any path which ends with `.html`
 | 
						|
  - `createProxyMiddleware('/*.html', {...})` matches paths directly under path-absolute
 | 
						|
  - `createProxyMiddleware('/api/**/*.html', {...})` matches requests ending with `.html` in the path of `/api`
 | 
						|
  - `createProxyMiddleware(['/api/**', '/ajax/**'], {...})` combine multiple patterns
 | 
						|
  - `createProxyMiddleware(['/api/**', '!**/bad.json'], {...})` exclusion
 | 
						|
 | 
						|
  **Note**: In multiple path matching, you cannot use string paths and wildcard paths together.
 | 
						|
 | 
						|
- **custom matching**
 | 
						|
 | 
						|
  For full control you can provide a custom function to determine which requests should be proxied or not.
 | 
						|
 | 
						|
  ```javascript
 | 
						|
  /**
 | 
						|
   * @return {Boolean}
 | 
						|
   */
 | 
						|
  const filter = function (pathname, req) {
 | 
						|
    return pathname.match('^/api') && req.method === 'GET';
 | 
						|
  };
 | 
						|
 | 
						|
  const apiProxy = createProxyMiddleware(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') }
 | 
						|
 | 
						|
  // custom rewriting, returning Promise
 | 
						|
  pathRewrite: async function (path, req) {
 | 
						|
    const should_add_something = await httpRequestToDecideSomething(path);
 | 
						|
    if (should_add_something) path += "something";
 | 
						|
    return path;
 | 
						|
  }
 | 
						|
  ```
 | 
						|
 | 
						|
- **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 (string target)
 | 
						|
  router: function(req) {
 | 
						|
      return 'http://localhost:8004';
 | 
						|
  }
 | 
						|
 | 
						|
  // Custom router function (target object)
 | 
						|
  router: function(req) {
 | 
						|
      return {
 | 
						|
          protocol: 'https:', // The : is required
 | 
						|
          host: 'localhost',
 | 
						|
          port: 8004
 | 
						|
      };
 | 
						|
  }
 | 
						|
 | 
						|
  // Asynchronous router function which returns promise
 | 
						|
  router: async function(req) {
 | 
						|
      const url = await doSomeIO();
 | 
						|
      return url;
 | 
						|
  }
 | 
						|
  ```
 | 
						|
 | 
						|
- **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) {
 | 
						|
    const logger = new (require('winston').Logger)();
 | 
						|
 | 
						|
    const myCustomProvider = {
 | 
						|
      log: logger.log,
 | 
						|
      debug: logger.debug,
 | 
						|
      info: logger.info,
 | 
						|
      warn: logger.warn,
 | 
						|
      error: logger.error,
 | 
						|
    };
 | 
						|
    return myCustomProvider;
 | 
						|
  }
 | 
						|
  ```
 | 
						|
 | 
						|
### 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, target) {
 | 
						|
    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', hybridParseAndLogMessage);
 | 
						|
  }
 | 
						|
  ```
 | 
						|
 | 
						|
- **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.preserveHeaderKeyCase**: true/false, Default: false - specify whether you want to keep letter case of response header key
 | 
						|
- **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:
 | 
						|
    ```json
 | 
						|
    cookieDomainRewrite: {
 | 
						|
      "unchanged.domain": "unchanged.domain",
 | 
						|
      "old.domain": "new.domain",
 | 
						|
      "*": ""
 | 
						|
    }
 | 
						|
    ```
 | 
						|
- **option.cookiePathRewrite**: rewrites path of `set-cookie` headers. Possible values:
 | 
						|
  - `false` (default): disable cookie rewriting
 | 
						|
  - String: new path, for example `cookiePathRewrite: "/newPath/"`. To remove the path, use `cookiePathRewrite: ""`. To set path to root use `cookiePathRewrite: "/"`.
 | 
						|
  - Object: mapping of paths to new paths, use `"*"` to match all paths.
 | 
						|
    For example, to keep one path unchanged, rewrite one path and remove other paths:
 | 
						|
    ```json
 | 
						|
    cookiePathRewrite: {
 | 
						|
      "/unchanged.path/": "/unchanged.path/",
 | 
						|
      "/old.path/": "/new.path/",
 | 
						|
      "*": ""
 | 
						|
    }
 | 
						|
    ```
 | 
						|
- **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
 | 
						|
- **option.timeout**: timeout (in millis) for incoming requests
 | 
						|
- **option.followRedirects**: true/false, Default: false - specify whether you want to follow redirects
 | 
						|
- **option.selfHandleResponse** true/false, if set to true, none of the webOutgoing passes are called and it's your responsibility to appropriately return the response by listening and acting on the `proxyRes` event
 | 
						|
- **option.buffer**: stream of data to send as the request body. Maybe you have some middleware that consumes the request stream before proxying it on e.g. If you read the body of a request into a field called 'req.rawbody' you could restream this field in the buffer option:
 | 
						|
 | 
						|
  ```javascript
 | 
						|
  'use strict';
 | 
						|
 | 
						|
  const streamify = require('stream-array');
 | 
						|
  const HttpProxy = require('http-proxy');
 | 
						|
  const proxy = new HttpProxy();
 | 
						|
 | 
						|
  module.exports = (req, res, next) => {
 | 
						|
    proxy.web(
 | 
						|
      req,
 | 
						|
      res,
 | 
						|
      {
 | 
						|
        target: 'http://localhost:4003/',
 | 
						|
        buffer: streamify(req.rawBody),
 | 
						|
      },
 | 
						|
      next
 | 
						|
    );
 | 
						|
  };
 | 
						|
  ```
 | 
						|
 | 
						|
## 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
 | 
						|
createProxyMiddleware('http://www.example.org:8000/api');
 | 
						|
// createProxyMiddleware('/api', {target: 'http://www.example.org:8000'});
 | 
						|
 | 
						|
createProxyMiddleware('http://www.example.org:8000/api/books/*/**.json');
 | 
						|
// createProxyMiddleware('/api/books/*/**.json', {target: 'http://www.example.org:8000'});
 | 
						|
 | 
						|
createProxyMiddleware('http://www.example.org:8000/api', { changeOrigin: true });
 | 
						|
// createProxyMiddleware('/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', createProxyMiddleware({ 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
 | 
						|
- polka: https://github.com/lukeed/polka#usebase-fn
 | 
						|
 | 
						|
## WebSocket
 | 
						|
 | 
						|
```javascript
 | 
						|
// verbose api
 | 
						|
createProxyMiddleware('/', { target: 'http://echo.websocket.org', ws: true });
 | 
						|
 | 
						|
// shorthand
 | 
						|
createProxyMiddleware('http://echo.websocket.org', { ws: true });
 | 
						|
 | 
						|
// shorter shorthand
 | 
						|
createProxyMiddleware('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
 | 
						|
const wsProxy = createProxyMiddleware('ws://echo.websocket.org', { changeOrigin: true });
 | 
						|
 | 
						|
const app = express();
 | 
						|
app.use(wsProxy);
 | 
						|
 | 
						|
const server = app.listen(3000);
 | 
						|
server.on('upgrade', wsProxy.upgrade); // <-- subscribe to http 'upgrade'
 | 
						|
```
 | 
						|
 | 
						|
## Intercept and manipulate requests
 | 
						|
 | 
						|
Intercept requests from downstream by defining `onProxyReq` in `createProxyMiddleware`.
 | 
						|
 | 
						|
Currently the only pre-provided request interceptor is `fixRequestBody`, which is used to fix proxied POST requests when `bodyParser` is applied before this middleware.
 | 
						|
 | 
						|
Example:
 | 
						|
 | 
						|
```javascript
 | 
						|
const { createProxyMiddleware, fixRequestBody } = require('http-proxy-middleware');
 | 
						|
 | 
						|
const proxy = createProxyMiddleware({
 | 
						|
  /**
 | 
						|
   * Fix bodyParser
 | 
						|
   **/
 | 
						|
  onProxyReq: fixRequestBody,
 | 
						|
});
 | 
						|
```
 | 
						|
 | 
						|
## Intercept and manipulate responses
 | 
						|
 | 
						|
Intercept responses from upstream with `responseInterceptor`. (Make sure to set `selfHandleResponse: true`)
 | 
						|
 | 
						|
Responses which are compressed with `brotli`, `gzip` and `deflate` will be decompressed automatically. The response will be returned as `buffer` ([docs](https://nodejs.org/api/buffer.html)) which you can manipulate.
 | 
						|
 | 
						|
With `buffer`, response manipulation is not limited to text responses (html/css/js, etc...); image manipulation will be possible too. ([example](https://github.com/chimurai/http-proxy-middleware/blob/master/recipes/response-interceptor.md#manipulate-image-response))
 | 
						|
 | 
						|
NOTE: `responseInterceptor` disables streaming of target's response.
 | 
						|
 | 
						|
Example:
 | 
						|
 | 
						|
```javascript
 | 
						|
const { createProxyMiddleware, responseInterceptor } = require('http-proxy-middleware');
 | 
						|
 | 
						|
const proxy = createProxyMiddleware({
 | 
						|
  /**
 | 
						|
   * IMPORTANT: avoid res.end being called automatically
 | 
						|
   **/
 | 
						|
  selfHandleResponse: true, // res.end() will be called internally by responseInterceptor()
 | 
						|
 | 
						|
  /**
 | 
						|
   * Intercept response and replace 'Hello' with 'Goodbye'
 | 
						|
   **/
 | 
						|
  onProxyRes: responseInterceptor(async (responseBuffer, proxyRes, req, res) => {
 | 
						|
    const response = responseBuffer.toString('utf8'); // convert buffer to string
 | 
						|
    return response.replace('Hello', 'Goodbye'); // manipulate response and return the result
 | 
						|
  }),
 | 
						|
});
 | 
						|
```
 | 
						|
 | 
						|
Check out [interception recipes](https://github.com/chimurai/http-proxy-middleware/blob/master/recipes/response-interceptor.md#readme) for more examples.
 | 
						|
 | 
						|
## 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))
 | 
						|
- Response Manipulation ([example source](https://github.com/chimurai/http-proxy-middleware/blob/master/examples/response-interceptor/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)
 | 
						|
- [fastify](https://www.npmjs.com/package/fastify)
 | 
						|
- [browser-sync](https://www.npmjs.com/package/browser-sync)
 | 
						|
- [lite-server](https://www.npmjs.com/package/lite-server)
 | 
						|
- [polka](https://github.com/lukeed/polka)
 | 
						|
- [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
 | 
						|
$ yarn
 | 
						|
 | 
						|
# linting
 | 
						|
$ yarn lint
 | 
						|
$ yarn lint:fix
 | 
						|
 | 
						|
# building (compile typescript to js)
 | 
						|
$ yarn build
 | 
						|
 | 
						|
# unit tests
 | 
						|
$ yarn test
 | 
						|
 | 
						|
# code coverage
 | 
						|
$ yarn cover
 | 
						|
 | 
						|
# check spelling mistakes
 | 
						|
$ yarn spellcheck
 | 
						|
```
 | 
						|
 | 
						|
## Changelog
 | 
						|
 | 
						|
- [View changelog](https://github.com/chimurai/http-proxy-middleware/blob/master/CHANGELOG.md)
 | 
						|
 | 
						|
## License
 | 
						|
 | 
						|
The MIT License (MIT)
 | 
						|
 | 
						|
Copyright (c) 2015-2025 Steven Chim
 |