http-proxy-middleware
Advanced tools
The one-liner node.js proxy middleware for connect, express and browser-sync
The http-proxy-middleware package is a Node.js package that provides an HTTP proxy as a middleware for use with Node.js applications, particularly in conjunction with frameworks like Express. It allows developers to easily set up proxy rules to forward requests to other servers, which is useful for tasks like API forwarding, logging, handling CORS, and more.
Proxy requests
This feature allows you to proxy requests to another server. In this example, all requests to '/api' on the local server are forwarded to 'http://www.example.org'.
const { createProxyMiddleware } = require('http-proxy-middleware');
const apiProxy = createProxyMiddleware('/api', { target: 'http://www.example.org' });
app.use('/api', apiProxy);Path Rewriting
This feature allows you to rewrite the path of the request URL before it gets proxied. In this example, the path '/api' is removed before the request is forwarded to 'http://www.example.org'.
const { createProxyMiddleware } = require('http-proxy-middleware');
const apiProxy = createProxyMiddleware('/api', {
target: 'http://www.example.org',
pathRewrite: { '^/api': '' }
});
app.use('/api', apiProxy);Custom Routing Logic
This feature allows you to implement custom routing logic. In this example, only GET requests to paths starting with '/api' are proxied to 'http://www.example.org'.
const { createProxyMiddleware } = require('http-proxy-middleware');
const apiProxy = createProxyMiddleware((pathname, req) => {
return pathname.match('^/api') && req.method === 'GET';
}, { target: 'http://www.example.org' });
app.use(apiProxy);Handling WebSockets
This feature allows you to proxy WebSocket connections. In this example, WebSocket connections to '/socket' are proxied to 'ws://www.example.org'.
const { createProxyMiddleware } = require('http-proxy-middleware');
const wsProxy = createProxyMiddleware('/socket', {
target: 'ws://www.example.org',
ws: true
});
app.use('/socket', wsProxy);express-http-proxy is similar to http-proxy-middleware but is specifically designed for use with Express. It offers similar features for proxying HTTP requests but may have different configuration options and middleware setup.
node-http-proxy is a full-featured HTTP proxy library for Node.js, which http-proxy-middleware is built upon. It provides more low-level control over proxying but requires more setup compared to the convenience middleware layer provided by http-proxy-middleware.
Redbird is a reverse proxy library for Node.js with built-in support for clustering, HTTP2, LetsEncrypt, and more. It is more feature-rich and suitable for more complex proxying needs compared to http-proxy-middleware, which is simpler and more focused on middleware use cases.
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. 
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.
:bulb: Tip: Set the option changeOrigin to true for name-based virtual hosted sites.
$ npm install --save-dev http-proxy-middleware
Proxy middleware configuration.
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.
(full list of http-proxy-middleware configuration options)
// shorthand syntax for the example above:
var apiProxy = proxy('http://www.example.org/api');
More about the shorthand configuration.
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: {
'^/old/api' : '/new/api', // rewrite path
'^/remove/api' : '/api' // remove path
},
proxyTable: {
// 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);
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. Request URL's path-absolute and query will be used for context matching.
path matching
proxy({...}) or proxy('/', {...}) - matches any path, all requests will be proxied.proxy('/api', {...}) - matches paths starting with /apimultiple 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 .htmlproxy('/*.html', {...}) matches paths directly under path-absoluteproxy('/api/**/*.html', {...}) matches requests ending with .html in the path of /apiproxy(['/api/**', '/ajax/**'], {...}) combine multiple patternsproxy(['/api/**', '!**/bad.json'], {...}) exclusioncustom matching
For full control you can provide a custom function to determine which requests should be proxied or not.
/**
* @return {Boolean}
*/
var filter = function (path, req) {
return (path.match('^/api') && req.method === 'GET');
};
var apiProxy = proxy(filter, {target: 'http://www.example.org'})
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) { return path.replace('/api', '/base/api') }
option.proxyTable: object, re-target option.target based on the request header host parameter. host can be used in conjunction with path. Only one instance of the proxy will be used. The order of the configuration matters.
proxyTable: {
'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
}
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.
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');
}
The following options are provided by the underlying http-proxy library.
path (useful for proxying to proxies){host:'www.example.org'})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});
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:
// 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');
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'
View and play around with working examples.
View the recipes for common use cases.
http-proxy-middleware is compatible with the following servers:
Sample implementations can be found in the server recipes.
Run the test suite:
# install dependencies
$ npm install
unit testing
# unit tests
$ npm test
coverage
# code coverage
$ npm run cover
The MIT License (MIT)
Copyright (c) 2015-2016 Steven Chim
FAQs
The one-liner node.js proxy middleware for connect, express, next.js and more
The npm package http-proxy-middleware receives a total of 9,886,410 weekly downloads. As such, http-proxy-middleware popularity was classified as popular.
We found that http-proxy-middleware demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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