---
title: Express vhost middleware
module: vhost
---

# vhost

[![NPM Version][npm-image]][npm-url]
[![NPM Downloads][downloads-image]][downloads-url]
[![Build Status][github-actions-ci-image]][github-actions-ci-url]
[![Test Coverage][coveralls-image]][coveralls-url]

## Install

```sh
$ npm install vhost
```

## API

```js
var vhost = require('vhost');
```

### vhost(hostname, handle)

Create a new middleware function to hand off request to `handle` when the incoming
host for the request matches `hostname`. The function is called as
`handle(req, res, next)`, like a standard middleware.

`hostname` can be a string or a RegExp object. When `hostname` is a string it can
contain `*` to match 1 or more characters in that section of the hostname. When
`hostname` is a RegExp, it will be forced to case-insensitive (since hostnames are)
and will be forced to match based on the start and end of the hostname.

When host is matched and the request is sent down to a vhost handler, the `req.vhost`
property will be populated with an object. This object will have numeric properties
corresponding to each wildcard (or capture group if RegExp object provided) and the
`hostname` that was matched.

```js
var connect = require('connect');
var vhost = require('vhost');
var app = connect();

app.use(
  vhost('*.*.example.com', function handle(req, res, next) {
    // for match of "foo.bar.example.com:8080" against "*.*.example.com":
    console.dir(req.vhost.host); // => 'foo.bar.example.com:8080'
    console.dir(req.vhost.hostname); // => 'foo.bar.example.com'
    console.dir(req.vhost.length); // => 2
    console.dir(req.vhost[0]); // => 'foo'
    console.dir(req.vhost[1]); // => 'bar'
  })
);
```

## Examples

### using with connect for static serving

```js
var connect = require('connect');
var serveStatic = require('serve-static');
var vhost = require('vhost');

var mailapp = connect();

// add middlewares to mailapp for mail.example.com

// create app to serve static files on subdomain
var staticapp = connect();
staticapp.use(serveStatic('public'));

// create main app
var app = connect();

// add vhost routing to main app for mail
app.use(vhost('mail.example.com', mailapp));

// route static assets for "assets-*" subdomain to get
// around max host connections limit on browsers
app.use(vhost('assets-*.example.com', staticapp));

// add middlewares and main usage to app

app.listen(3000);
```

### using with connect for user subdomains

```js
var connect = require('connect');
var serveStatic = require('serve-static');
var vhost = require('vhost');

var mainapp = connect();

// add middlewares to mainapp for the main web site

// create app that will server user content from public/{username}/
var userapp = connect();

userapp.use(function (req, res, next) {
  var username = req.vhost[0]; // username is the "*"

  // pretend request was for /{username}/* for file serving
  req.originalUrl = req.url;
  req.url = '/' + username + req.url;

  next();
});
userapp.use(serveStatic('public'));

// create main app
var app = connect();

// add vhost routing for main app
app.use(vhost('userpages.local', mainapp));
app.use(vhost('www.userpages.local', mainapp));

// listen on all subdomains for user pages
app.use(vhost('*.userpages.local', userapp));

app.listen(3000);
```

### using with any generic request handler

```js
var connect = require('connect');
var http = require('http');
var vhost = require('vhost');

// create main app
var app = connect();

app.use(
  vhost('mail.example.com', function (req, res) {
    // handle req + res belonging to mail.example.com
    res.setHeader('Content-Type', 'text/plain');
    res.end('hello from mail!');
  })
);

// an external api server in any framework
var httpServer = http.createServer(function (req, res) {
  res.setHeader('Content-Type', 'text/plain');
  res.end('hello from the api!');
});

app.use(
  vhost('api.example.com', function (req, res) {
    // handle req + res belonging to api.example.com
    // pass the request to a standard Node.js HTTP server
    httpServer.emit('request', req, res);
  })
);

app.listen(3000);
```

## License

[MIT](LICENSE)

[npm-image]: https://img.shields.io/npm/v/vhost.svg
[npm-url]: https://npmjs.org/package/vhost
[coveralls-image]: https://img.shields.io/coveralls/expressjs/vhost/master.svg
[coveralls-url]: https://coveralls.io/r/expressjs/vhost
[downloads-image]: https://img.shields.io/npm/dm/vhost.svg
[downloads-url]: https://npmjs.org/package/vhost
[github-actions-ci-image]: https://img.shields.io/github/actions/workflow/status/expressjs/vhost/ci.yml?branch=master&label=ci
[github-actions-ci-url]: https://github.com/expressjs/vhost/actions/workflows/ci.yml
