Configure http2-proxy middleware with ease for koa.


710.0.4a year ago2 years agoMinified + gzip package size for koa-http2-proxy in KB



Configure http2-proxy middleware with ease for koa.

Based on http-proxy-middleware.


Proxy requests to http://www.example.org

var Koa = require('koa');
var proxy = require('koa-http2-proxy');
var app = new Koa();

// response
app.use(proxy({ target: 'http://www.example.org' }));


// http://localhost:3000/foo/bar -> http://www.example.org/foo/bar

:bulb: Tip: Set the option changeOrigin to true for name-based virtual hosted sites.

Table of Contents


$ npm install --save-dev koa-http2-proxy

Core concept

Proxy middleware configuration.

proxy([context,] config)

var proxy = require('koa-http2-proxy');

var apiProxy = proxy('/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)
  • options.target: target host to proxy to. (protocol + host)

(full list of koa-http2-proxy configuration options)

proxy(uri [, config])

// shorthand syntax for the example above:
var apiProxy = proxy('http://www.example.org/api');

More about the shorthand configuration.


// include dependencies
var Koa = require('koa');
var proxy = require('koa-http2-proxy');

// proxy middleware options
var options = {
  target: 'http://www.example.org', // target host
  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)
var exampleProxy = proxy(options);

// mount `exampleProxy` in web server
var app = new Koa();

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 to mount the proxy or when you need more flexibility.

RFC 3986 path is used for context matching.

         \_/   \______________/\_________/ \_________/ \__/
          |           |            |            |        |
       scheme     authority       path        query   fragment
  • path matching

    • proxy({...}) - matches any path, all requests will be proxied.
    • proxy('/', {...}) - matches any path, all requests will be proxied.
    • proxy('/api', {...}) - matches paths starting with /api
  • multiple 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 .html
    • proxy('/*.html', {...}) matches paths directly under path-absolute
    • proxy('/api/**/*.html', {...}) matches requests ending with .html in the path of /api
    • proxy(['/api/**', '/ajax/**'], {...}) combine multiple patterns
    • proxy(['/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}
    var filter = function(pathname, req) {
      return pathname.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, req) { return path.replace('/api', '/base/api') }
  • option.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://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
    router: function(req) {
        return 'http://localhost:8004';
  • 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;
  • option.onError: function, subscribe to http-proxy's error event for custom error handling.

    function onError(err, ctx) {
      ctx.response.status = 500;
      ctx.response.body =
        'Something went wrong. And we are reporting a custom error message.';
  • option.onProxyRes: function, subscribe to http-proxy's proxyRes event.

    function onProxyRes(proxyRes, ctx) {
      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, ctx) {
      // add custom header to request
      proxyReq.setHeader('x-added', 'foobar');
      // or log the req
  • option.onUpgrade: function, called before upgrading a websocket connection.

    onUpgrade: async ctx => {
      // add session middleware to the websocket connection
      // see option.app
      await session(ctx, () => {});
  • option.app: koa app, used to generate a koa ctx to be used in onUpgrade. If left blank, a object containing only req will be used as context

  • option.headers: object, adds request headers. (Example: {host:'www.example.org'})

  • option.target: url string to be parsed with the url module

  • option.ws: true/false: if you want to proxy websockets

  • option.xfwd: true/false, adds x-forward headers

  • option.changeOrigin: true/false, Default: false - changes the origin of the host header to the target URL

  • option.proxyTimeout: timeout (in millis) when proxy receives no response from target

  • option.proxyName: Proxy name used for Via header


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('/api', {target: 'http://www.example.org:8000'});

// proxy('/api/books/*/**.json', {target: 'http://www.example.org:8000'});

// proxy('/api', {target: 'http://www.example.org:8000'});


// verbose api
proxy('/', { target: 'http://echo.websocket.org', ws: true });

// shorthand
proxy('http://echo.websocket.org', { ws: true });

// shorter shorthand

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.

var wsProxy = proxy('ws://echo.websocket.org');

var app = new Koa();

var server = app.listen(3000);
server.on('upgrade', wsProxy.upgrade); // <-- subscribe to http 'upgrade'


Run the test suite:

# install dependencies
$ yarn

# linting
$ yarn lint
$ yarn lint:fix

# building (compile typescript to js)
$ yarn build

# unit tests
$ yarn test

# code coverage
$ yarn cover



The MIT License (MIT)

Copyright for portions of this project are held by Steven Chim, 2015-2019 as part of http-proxy-middleware. All other copyright for this project are held by Ontola BV, 2019.

If you find any bugs or have a feature request, please open an issue on github!

The npm package download data comes from npm's download counts api and package details come from npms.io.