http-proxy-middleware

Node.js proxying made simple. Configure proxy middleware with ease for connect, express, next.js and many more.

⚠️ Note

This page is showing documentation for version v3.x.x (release notes)

See 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.

// 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<Request, Response>({
    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 can be used, along with some extra http-proxy-middleware options.

Table of Contents

Install
Basic usage
Express Server Example
- app.use(path, proxy)
Options
http-proxy events
http-proxy options
WebSocket
- External WebSocket upgrade
Intercept and manipulate requests
Intercept and manipulate responses
Node.js 17+: ECONNREFUSED issue with IPv6 and localhost (#705)
Debugging
Working examples
Recipes
Compatible servers
Tests
Changelog
License

Install

npm install --save-dev http-proxy-middleware

Basic usage

Create and configure a proxy middleware with: createProxyMiddleware(config).

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

Express Server Example

An example with express server.

// 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<express.Request, express.Response>} */
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.

app.use(
  createProxyMiddleware({
    target: 'http://www.example.org/api',
    changeOrigin: true,
    pathFilter: '/api/proxy-only-this-path',
  }),
);

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

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 or 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.

/**
 * @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.

// 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.

// 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)

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.

// 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: https://github.com/winstonjs/winston#string-interpolation

See also logger recipes (recipes/logger.md) for more details.

createProxyMiddleware({
  logger: console,
});

`http-proxy` events

Subscribe to http-proxy events with the on option:

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.

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.

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.

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.

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.

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.

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 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 and 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,