# http-proxy-middleware [![GitHub Workflow Status (with branch)](https://img.shields.io/github/actions/workflow/status/chimurai/http-proxy-middleware/ci.yml?branch=master&logo=github-actions&logoColor=white&style=flat-square)](https://github.com/chimurai/http-proxy-middleware/actions/workflows/ci.yml?query=branch%3Amaster) [![Coveralls](https://img.shields.io/coveralls/chimurai/http-proxy-middleware.svg?style=flat-square&logo=coveralls)](https://coveralls.io/r/chimurai/http-proxy-middleware) [![Known Vulnerabilities](https://snyk.io/test/github/chimurai/http-proxy-middleware/badge.svg)](https://snyk.io/test/github/chimurai/http-proxy-middleware) [![npm](https://img.shields.io/npm/v/http-proxy-middleware?color=%23CC3534&style=flat-square&logo=npm)](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/expressjs/express), [next.js](https://github.com/vercel/next.js) and [many more](#compatible-servers). Powered by the popular Nodejitsu [`http-proxy`](https://github.com/http-party/node-http-proxy). [![GitHub stars](https://img.shields.io/github/stars/http-party/node-http-proxy.svg?style=social&label=Star)](https://github.com/http-party/node-http-proxy) ## ⚠️ Note This page is showing documentation for version v3.x.x ([release notes](https://github.com/chimurai/http-proxy-middleware/releases)) See [MIGRATION.md](https://github.com/chimurai/http-proxy-middleware/blob/master/MIGRATION.md) for details on how to migrate from v2.x.x to v3.x.x If you're looking for older documentation. Go to: - - ## TL;DR Proxy `/api` requests to `http://www.example.org` :bulb: **Tip:** Set the option `changeOrigin` to `true` for [name-based virtual hosted sites](http://en.wikipedia.org/wiki/Virtual_hosting#Name-based). ```typescript // typescript import * as express from 'express'; import type { Request, Response, NextFunction } from 'express'; import { createProxyMiddleware } from 'http-proxy-middleware'; import type { Filter, Options, RequestHandler } from 'http-proxy-middleware'; const app = express(); const proxyMiddleware = createProxyMiddleware({ target: 'http://www.example.org/api', changeOrigin: true, }); app.use('/api', proxyMiddleware); app.listen(3000); // proxy and keep the same base path "/api" // http://127.0.0.1:3000/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). ## Table of Contents - [Install](#install) - [Basic usage](#basic-usage) - [Express Server Example](#express-server-example) - [app.use(path, proxy)](#appusepath-proxy) - [Options](#options) - [`pathFilter` (string, \[\]string, glob, \[\]glob, function)](#pathfilter-string-string-glob-glob-function) - [`pathRewrite` (object/function)](#pathrewrite-objectfunction) - [`router` (object/function)](#router-objectfunction) - [`plugins` (Array)](#plugins-array) - [`ejectPlugins` (boolean) default: `false`](#ejectplugins-boolean-default-false) - [`logger` (Object)](#logger-object) - [`http-proxy` events](#http-proxy-events) - [`http-proxy` options](#http-proxy-options) - [WebSocket](#websocket) - [External WebSocket upgrade](#external-websocket-upgrade) - [Intercept and manipulate requests](#intercept-and-manipulate-requests) - [Intercept and manipulate responses](#intercept-and-manipulate-responses) - [Node.js 17+: ECONNREFUSED issue with IPv6 and localhost (#705)](#nodejs-17-econnrefused-issue-with-ipv6-and-localhost-705) - [Debugging](#debugging) - [Working examples](#working-examples) - [Recipes](#recipes) - [Compatible servers](#compatible-servers) - [Tests](#tests) - [Changelog](#changelog) - [License](#license) ## Install ```shell npm install --save-dev http-proxy-middleware ``` ## Basic usage Create and configure a proxy middleware with: `createProxyMiddleware(config)`. ```javascript const { createProxyMiddleware } = require('http-proxy-middleware'); const apiProxy = createProxyMiddleware({ target: 'http://www.example.org', changeOrigin: true, }); // 'apiProxy' is now ready to be used as middleware in a server. ``` - **options.target**: target host to proxy to. _(protocol + host)_ - **options.changeOrigin**: for virtual hosted sites - see full list of [`http-proxy-middleware` configuration options](#options) ## Express Server Example An example with `express` server. ```javascript // include dependencies const express = require('express'); const { createProxyMiddleware } = require('http-proxy-middleware'); const app = express(); // create the proxy /** @type {import('http-proxy-middleware/dist/types').RequestHandler} */ const exampleProxy = createProxyMiddleware({ target: 'http://www.example.org/api', // target host with the same base path changeOrigin: true, // needed for virtual hosted sites }); // mount `exampleProxy` in web server app.use('/api', exampleProxy); app.listen(3000); ``` ### app.use(path, proxy) If you want to use the server's `app.use` `path` parameter to match requests. Use `pathFilter` option to further include/exclude requests which you want to proxy. ```javascript app.use( createProxyMiddleware({ target: 'http://www.example.org/api', changeOrigin: true, pathFilter: '/api/proxy-only-this-path', }), ); ``` `app.use` documentation: - express: - connect: - polka: ## Options http-proxy-middleware options: ### `pathFilter` (string, []string, glob, []glob, function) Narrow down which requests should be proxied. The `path` used for filtering is the `request.url` pathname. In Express, this is the `path` relative to the mount-point of the proxy. - **path matching** - `createProxyMiddleware({...})` - matches any path, all requests will be proxied when `pathFilter` is not configured. - `createProxyMiddleware({ pathFilter: '/api', ...})` - matches paths starting with `/api` - **multiple path matching** - `createProxyMiddleware({ pathFilter: ['/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({ pathFilter: '**', ...})` matches any path, all requests will be proxied. - `createProxyMiddleware({ pathFilter: '**/*.html', ...})` matches any path which ends with `.html` - `createProxyMiddleware({ pathFilter: '/*.html', ...})` matches paths directly under path-absolute - `createProxyMiddleware({ pathFilter: '/api/**/*.html', ...})` matches requests ending with `.html` in the path of `/api` - `createProxyMiddleware({ pathFilter: ['/api/**', '/ajax/**'], ...})` combine multiple patterns - `createProxyMiddleware({ pathFilter: ['/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 pathFilter = function (path, req) { return path.match('^/api') && req.method === 'GET'; }; const apiProxy = createProxyMiddleware({ target: 'http://www.example.org', pathFilter: pathFilter, }); ``` ### `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; } ``` ### `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://127.0.0.1:8001', // host only 'staging.localhost:3000' : 'http://127.0.0.1:8002', // host only 'localhost:3000/api' : 'http://127.0.0.1:8003', // host + path '/rest' : 'http://127.0.0.1:8004' // path only } // Custom router function (string target) router: function(req) { return 'http://127.0.0.1:8004'; } // Custom router function (target object) router: function(req) { return { protocol: 'https:', // The : is required host: '127.0.0.1', port: 8004 }; } // Asynchronous router function which returns promise router: async function(req) { const url = await doSomeIO(); return url; } ``` ### `plugins` (Array) ```js const simpleRequestLogger = (proxyServer, options) => { proxyServer.on('proxyReq', (proxyReq, req, res) => { console.log(`[HPM] [${req.method}] ${req.url}`); // outputs: [HPM] GET /users }); }, const config = { target: `http://example.org`, changeOrigin: true, plugins: [simpleRequestLogger], }; ``` ### `ejectPlugins` (boolean) default: `false` If you're not satisfied with the pre-configured plugins, you can eject them by configuring `ejectPlugins: true`. NOTE: register your own error handlers to prevent server from crashing. ```js // eject default plugins and manually add them back const { debugProxyErrorsPlugin, // subscribe to proxy errors to prevent server from crashing loggerPlugin, // log proxy events to a logger (ie. console) errorResponsePlugin, // return 5xx response on proxy error proxyEventsPlugin, // implements the "on:" option } = require('http-proxy-middleware'); createProxyMiddleware({ target: `http://example.org`, changeOrigin: true, ejectPlugins: true, plugins: [debugProxyErrorsPlugin, loggerPlugin, errorResponsePlugin, proxyEventsPlugin], }); ``` ### `logger` (Object) Configure a logger to output information from http-proxy-middleware: ie. `console`, `winston`, `pino`, `bunyan`, `log4js`, etc... Only `info`, `warn`, `error` are used internally for compatibility across different loggers. If you use `winston`, make sure to enable interpolation: See also logger recipes ([recipes/logger.md](https://github.com/chimurai/http-proxy-middleware/blob/master/recipes/logger.md)) for more details. ```javascript createProxyMiddleware({ logger: console, }); ``` ## `http-proxy` events Subscribe to [http-proxy events](https://github.com/nodejitsu/node-http-proxy#listening-for-proxy-events) with the `on` option: ```js createProxyMiddleware({ target: 'http://www.example.org', on: { proxyReq: (proxyReq, req, res) => { /* handle proxyReq */ }, proxyRes: (proxyRes, req, res) => { /* handle proxyRes */ }, error: (err, req, res) => { /* handle error */ }, }, }); ``` - **option.on.error**: 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.on.proxyRes**: 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.on.proxyReq**: 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.on.proxyReqWs**: 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.on.open**: 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.on.close**: 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://127.0.0.1:4003/', buffer: streamify(req.rawBody), }, next, ); }; ``` ## WebSocket ```javascript // verbose api createProxyMiddleware({ pathFilter: '/', target: 'http://echo.websocket.org', ws: true }); ``` ### 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({ target: '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 **/ on: { proxyReq: 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' **/ on: { proxyRes: 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. ## Node.js 17+: ECONNREFUSED issue with IPv6 and localhost ([#705](https://github.com/chimurai/http-proxy-middleware/issues/705)) Node.js 17+ no longer prefers IPv4 over IPv6 for DNS lookups. E.g. It's **not** guaranteed that `localhost` will be resolved to `127.0.0.1` – it might just as well be `::1` (or some other IP address). If your target server only accepts IPv4 connections, trying to proxy to `localhost` will fail if resolved to `::1` (IPv6). Ways to solve it: - Change `target: "http://localhost"` to `target: "http://127.0.0.1"` (IPv4). - Change the target server to (also) accept IPv6 connections. - Add this flag when running `node`: `node index.js --dns-result-order=ipv4first`. (Not recommended.) > Note: There’s a thing called [Happy Eyeballs](https://en.wikipedia.org/wiki/Happy_Eyeballs) which means connecting to both IPv4 and IPv6 in parallel, which Node.js doesn’t have, but explains why for example `curl` can connect. ## Debugging Configure the `DEBUG` environment variable enable debug logging. See [`debug`](https://github.com/debug-js/debug#readme) project for more options. ```shell DEBUG=http-proxy-middleware* node server.js $ http-proxy-middleware proxy created +0ms $ http-proxy-middleware proxying request to target: 'http://www.example.org' +359ms ``` ## 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) - [next.js](https://www.npmjs.com/package/next) - [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

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