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# 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)
## ⚠️ 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) 2015-2022 Steven Chim

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