redbird/README.md

# Redbird Reverse Proxy

## With built in Cluster, HTTP2, [LetsEncrypt](https://letsencrypt.org/) and [Docker](https://www.docker.com/) support


![redbird](http://cliparts.co/cliparts/6cr/o9d/6cro9dRzi.jpg)

Handling dynamic virtual hosts, load balancing, proxying web sockets and SSL encryption should be
easy and robust.

With redbird you get a complete library to build dynamic reverse proxies with the speed and robustness of http-proxy.

This light-weight package includes everything you need for easy reverse routing of your applications.
Great for routing many applications from different domains in one single host, handling SSL with ease, etc.

Developed by [manast](http://twitter.com/manast)

[![BuildStatus](https://secure.travis-ci.org/OptimalBits/redbird.png?branch=master)](http://travis-ci.org/OptimalBits/redbird)
[![NPM version](https://badge.fury.io/js/redbird.svg)](http://badge.fury.io/js/redbird)

## SUPER HOT

Support for HTTP2. You can now enable HTTP2 just by setting the HTTP2 flag to true. Keep in mind that HTTP2 requires
SSL/TLS certificates. Thankfully we also support LetsEncrypt so this becomes easy as pie.

## HOT

We have now support for automatic generation of SSL certificates using [LetsEncrypt](#letsencrypt). Zero config setup for your
TLS protected services that just works.

## Features

- Flexible and easy routing
- Websockets
- Seamless SSL Support (HTTPS -> HTTP proxy)
- Automatic HTTP to HTTPS redirects
- Automatic TLS Certificates generation and renewal
- Load balancer
- Register and unregister routes programatically without restart (allows zero downtime deployments)
- Docker support for automatic registration of running containers
- Cluster support that enables automatic multi-process
- Based on top of rock-solid node-http-proxy and battle tested on production in many sites
- Optional logging based on bunyan

## Install


```sh
npm install redbird
```

## Example


You can programmatically register or unregister routes dynamically even if the proxy is already running:

```js
var proxy = require('redbird')({port: 80});

// OPTIONAL: Setup your proxy but disable the X-Forwarded-For header
var proxy = require('redbird')({port: 80, xfwd: false});

// Route to any global ip
proxy.register("optimalbits.com", "http://167.23.42.67:8000");

// Route to any local ip, for example from docker containers.
proxy.register("example.com", "http://172.17.42.1:8001");

// Route from hostnames as well as paths
proxy.register("example.com/static", "http://172.17.42.1:8002");
proxy.register("example.com/media", "http://172.17.42.1:8003");

// Subdomains, paths, everything just works as expected
proxy.register("abc.example.com", "http://172.17.42.4:8080");
proxy.register("abc.example.com/media", "http://172.17.42.5:8080");

// Route to any href including a target path
proxy.register("foobar.example.com", "http://172.17.42.6:8080/foobar");

// You can also enable load balancing by registering the same hostname with different
// target hosts. The requests will be evenly balanced using a Round-Robin scheme.
proxy.register("balance.me", "http://172.17.40.6:8080");
proxy.register("balance.me", "http://172.17.41.6:8080");
proxy.register("balance.me", "http://172.17.42.6:8080");
proxy.register("balance.me", "http://172.17.43.6:8080");


// LetsEncrypt support
// With Redbird you can get zero conf and automatic SSL certificates for your domains
redbird.register('example.com', 'http://172.60.80.2:8082', {
	ssl: {
    letsencrypt: {
      email: 'john@example.com', // Domain owner/admin email
      production: true, // WARNING: Only use this flag when the proxy is verified to work correctly to avoid being banned!
    }
  }
});

//
// LetsEncrypt requires a minimal web server for handling the challenges, this is by default on port 3000
// it can be configured when initiating the proxy. This web server is only used by Redbird internally so most of the time
// you  do not need to do anything special other than avoid having other web services in the same host running
// on the same port.

//
// HTTP2 Support using LetsEncrypt for the certificates
//
var proxy = require('redbird')({
  letsencrypt: {
    path: __dirname + '/certs',
    port:9999
  },
  ssl: {
    http2: true,
  }
});

```
## About HTTPS

The HTTPS proxy supports virtual hosts by using SNI (which most modern browsers support: IE7 and above).
The proxying is performed by hostname, so you must use the same SSL certificates for a given hostname independently of its paths.

### LetsEncrypt

Some important considerations when using LetsEncrypt. You need to agree to LetsEncrypt [terms of service](https://letsencrypt.org/documents/LE-SA-v1.0.1-July-27-2015.pdf). When using
LetsEncrypt, the obtained certificates will be copied to disk to the specified path. Its your responsibility to backup, or save persistently when applicable. Keep in mind that
these certificates needs to be handled with care so that they cannot be accessed by malicious users. The certificates will be renewed every
2 months automatically forever.

## HTTPS Example

(NOTE: This is a legacy example not needed when using LetsEncrypt)

Conceptually HTTPS is easy, but it is also easy to struggle getting it right. With Redbird its straightforward, check this complete example:

1) Generate a localhost development SSL certificate:

```sh
/certs $ openssl genrsa -out dev-key.pem 1024
/certs $ openssl req -new -key dev-key.pem -out dev-csr.pem

// IMPORTANT: Do not forget to fill the field! Common Name (e.g. server FQDN or YOUR name) []:localhost

/certs $ openssl x509 -req -in dev-csr.pem -signkey dev-key.pem -out dev-cert.pem

```

Note: For production sites you need to buy valid SSL certificates from a trusted authority.

2) Create a simple redbird based proxy:

```js
var redbird = new require('redbird')({
	port: 8080,

	// Specify filenames to default SSL certificates (in case SNI is not supported by the
	// user's browser)
	ssl: {
		port: 8443,
		key: "certs/dev-key.pem",
		cert: "certs/dev-cert.pem",
	}
});

// Since we will only have one https host, we dont need to specify additional certificates.
redbird.register('localhost', 'http://localhost:8082', {ssl: true});
```

3) Test it:

Point your browser to ```localhost:8000``` and you will see how it automatically redirects to your https server and proxies you to
your target server.


You can define many virtual hosts, each with its own SSL certificate. And if you do not define any, they will use the default one
as in the example above:

```js
redbird.register('example.com', 'http://172.60.80.2:8082', {
	ssl: {
		key: "../certs/example.key",
		cert: "../certs/example.crt",
		ca: "../certs/example.ca"
	}
});

redbird.register('foobar.com', 'http://172.60.80.3:8082', {
	ssl: {
		key: "../certs/foobar.key",
		cert: "../certs/foobar.crt",
	}
});
```

You can also specify https hosts as targets and also specify if you want the connection to the target host to be secure (default is true).

```js
var redbird = require('redbird')({
	port: 80,
	secure: false,
	ssl: {
		port: 443,
		key: "../certs/default.key",
		cert: "../certs/default.crt",
	}
});
redbird.register('tutorial.com', 'https://172.60.80.2:8083', {
	ssl: {
		key: "../certs/tutorial.key",
		cert: "../certs/tutorial.crt",
	}
});

```

Edge case scenario: you have an HTTPS server with two IP addresses assigned to it and your clients use old software without SNI support. In this case, both IP addresses will receive the same fallback certificate. I.e. some of the domains will get a wrong certificate. To handle this case you can create two HTTPS servers each one bound to its own IP address and serving the appropriate certificate.

```js
var redbird = new require('redbird')({
	port: 8080,

	// Specify filenames to default SSL certificates (in case SNI is not supported by the
	// user's browser)
	ssl: [
		{
			port: 443,
			ip: '123.45.67.10',  // assigned to tutorial.com
			key: 'certs/tutorial.key',
			cert: 'certs/tutorial.crt',
		},
		{
			port: 443,
			ip: '123.45.67.11', // assigned to my-other-domain.com
			key: 'certs/my-other-domain.key',
			cert: 'certs/my-other-domain.crt',
		}				
	]
});

// These certificates will be served if SNI is supported
redbird.register('tutorial.com', 'http://192.168.0.10:8001', {
	ssl: {
		key: 'certs/tutorial.key',
		cert: 'certs/tutorial.crt',
	}
});
redbird.register('my-other-domain.com', 'http://192.168.0.12:8001', {
	ssl: {
		key: 'certs/my-other-domain.key',
		cert: 'certs/my-other-domain.crt',
	}
});
```

## Docker support
If you use docker, you can tell Redbird to automatically register routes based on image
names. You register your image name and then every time a container starts from that image,
it gets registered, and unregistered if the container is stopped. If you run more than one
container from the same image, Redbird will load balance following a round-robin algorithm:

```js
var redbird = require('redbird')({
  port: 8080,
});

var docker = require('redbird').docker;
docker(redbird).register("old.api.com", 'company/api:v1.0.0');
docker(redbird).register("stable.api.com", 'company/api:v2.*');
docker(redbird).register("preview.api.com", 'company/api:v[3-9].*');
```

## etcd backend
Redbird can use [node-etcd](https://github.com/stianeikeland/node-etcd) to automatically create proxy records from an etcd cluster. Configuration
is accomplished by passing an array of [options](https://github.com/stianeikeland/node-etcd#constructor-options), plus the hosts and path variables,
which define which etcd cluster hosts, and which directory within those hosts, that Redbird should poll for updates.

```js
var redbird = require('redbird')({
  port:8080
});

var options = {
  hosts: ['localhost:2379'], // REQUIRED - you must define array of cluster hosts
	path: ['redbird'], // OPTIONAL - path to etcd keys
	... // OPTIONAL - pass in node-etcd connection options
}
require('redbird').etcd(redbird,options);
```
etcd records can be created in one of two ways, either as a target destination pair:
```/redbird/example.com			"8.8.8.8"```
or by passing a JSON object containing multiple hosts, and Redbird options:
```
/redbird/derek.com				{ "hosts" : ["10.10.10.10", "11.11.11.11"]}
/redbird/johnathan.com    { "ssl" : true }
/redbird/jeff.com         { "docker" : "alpine/alpine:latest" }
```


## Cluster support
Redbird support automatic support for node cluster. Just specify in the options object
the number of processes that you want Redbird to use. Redbird will automatically re-start
any thread thay may crash automatically, increasing even more its reliability.

```js
var redbird = new require('redbird')({
	port: 8080,
  cluster: 4
});
```

## NTLM support
If you need NTLM support, you can tell Redbird to add the required header handler. This
registers a response handler which makes sure the NTLM auth header is properly split into
two entries from http-proxy.

```js
var redbird = new require('redbird')({
  port: 8080,
  ntlm: true
});
```

## Custom Resolvers

With custom resolvers, you can decide how the proxy server handles request. Custom resolvers allow you to extend Redbird considerably. With custom resolvers, you can perform the following:

- Do path-based routing
- Do wildcard domain routing.
- Use variable upstream servers based on availability, for example in conjunction with Etcd or any other service discovery platform.
- And more.

Resolvers should be:

  1. Be invokable function. The `this` context of such function is the Redbird Proxy object. The resolver function takes in two parameters : `host` and `url`
  2. Have a priority, resolvers with higher priorities are called before those of lower priorities. The default resolver, has a priority of 0.
  3. A resolver should return a route object or a string when matches it matches the parameters passed in. If string is returned, then it must be a valid upstream URL, if object, then the object must conform to the following:

```
  {
     url: string or array of string [required], when array, the urls will be load-balanced across.
     path: path prefix for route, [optional], defaults to '/',
     opts: {} // Redbird target options, see Redbird.register() [optional],
  }
```

### Defining Resolvers

Resolvers can be defined when initializing the proxy object with the `resolvers` parameter. An example is below:

```javascript
 // for every URL path that starts with /api/, send request to upstream API service
 var customResolver1 = function(host, url) {
   if(/^\/api\//.test(url)){
      return 'http://127.0.0.1:8888';
   }
 };

 // assign high priority
 customResolver1.priority = 100;

 var proxy = new require('redbird')({
    port: 8080,
    resolvers: [
    customResolver1,
    // uses the same priority as default resolver, so will be called after default resolver
    function(host, url) {
      if(/\.example\.com/.test(host)){
        return 'http://127.0.0.1:9999'
      }
    }]
 })

```

### Adding and Removing Resolvers at Runtime.

You can add or remove resolvers at runtime, this is useful in situations where your upstream is tied to a service discovery service system.

```javascript
var topPriority = function(host, url) {
  return /app\.example\.com/.test(host) ? {
    // load balanced
    url: [
    'http://127.0.0.1:8000',
    'http://128.0.1.1:9999'
   ]
  } : null;
};

topPriority.priority = 200;
proxy.addResolver(topPriority);


// remove top priority after 10 minutes,
setTimeout(function() {
  proxy.removeResolver(topPriority);
}, 600000);
```

## Replacing the default HTTP/HTTPS server modules

By passing `serverModule: module` or `ssl: {serverModule : module}` you can override the default http/https 
servers used to listen for connections with another module.

One application for this is to enable support for PROXY protocol: This is useful if you want to use a module like 
[findhit-proxywrap](https://github.com/findhit/proxywrap) to enable support for the 
[PROXY protocol](http://www.haproxy.org/download/1.8/doc/proxy-protocol.txt).
 
                                                                  
PROXY protocol is used in tools like HA-Proxy, and can be optionally enabled in Amazon ELB load balancers to pass the 
original client IP when proxying TCP connections (similar to an X-Forwarded-For header, but for raw TCP). This is useful 
if you want to run redbird on AWS behind an ELB load balancer, but have redbird terminate any HTTPS connections so you 
can have SNI/Let's Encrypt/HTTP2support. With this in place Redbird will see the client's IP address rather 
than the load-balancer's, and pass this through in an X-Forwarded-For header.

````javascript
//Options for proxywrap. This means the proxy will also respond to regular HTTP requests without PROXY information as well.
proxy_opts = {strict: false}; 
proxyWrap = require('findhit-proxywrap');
var opts = {
    port: process.env.HTTP_PORT,
    serverModule = proxyWrap.proxy( require('http'), proxy_opts),
    ssl: {
        //Do this if you want http2:
        http2: true,        
        serverModule = proxyWrap.proxy(require('spdy').server, proxy_opts),
        //Do this if you only want regular https
        // serverModule = proxyWrap.proxy( require('http'), proxy_opts), 
        port: process.env.HTTPS_PORT,
    }
}

// Create the proxy
var proxy = require('redbird')(opts);
````


## Roadmap

- Statistics (number of connections, load, response times, etc)
- CORS support.
- Rate limiter.
- Simple IP Filtering.
- Automatic routing via Redis.

## Reference

[constructor](#redbird)
[register](#register)
[unregister](#unregister)
[notFound](#notFound)
[close](#close)

<a name="redbird"/>

### Redbird(opts)

This is the Proxy constructor. Creates a new Proxy and starts listening to
the given port.

__Arguments__

```
    opts {Object} Options to pass to the proxy:
    {
    	port: {Number} // port number that the proxy will listen to.
    	ssl: { // Optional SSL proxying.
    		port: {Number} // SSL port the proxy will listen to.
    		// Default certificates
    		key: keyPath,
    		cert: certPath,
    		ca: caPath // Optional.
            redirect: true, // Disable HTTPS autoredirect to this route.
            http2: false, //Optional, setting to true enables http2/spdy support
            serverModule : require('https') // Optional, override the https server module used to listen for https or http2 connections.  Default is require('https') or require('spdy')
    	}
        bunyan: {Object} Bunyan options. Check [bunyan](https://github.com/trentm/node-bunyan) for info.
        If you want to disable bunyan, just set this option to false. Keep in mind that
        having logs enabled incours in a performance penalty of about one order of magnitude per request.
        resolvers: {Function | Array}  a list of custom resolvers. Can be a single function or an array of functions. See more details about resolvers above.
        serverModule : {Module} Optional - Override the http server module used to listen for http connections.  Default is require('http') 
	}
```

---------------------------------------

<a name="register"/>

#### Redbird::register(src, target, opts)

Register a new route. As soon as this method is called, the proxy will
start routing the sources to the given targets.

__Arguments__

```javascript
    src {String} {String|URL} A string or a url parsed by node url module.
    	Note that port is ignored, since the proxy just listens to one port.

    target {String|URL} A string or a url parsed by node url module.
    opts {Object} route options:
    examples:
    {ssl : true} // Will use default ssl certificates.
    {ssl: {
        redirectPort: port, // optional https port number to be redirected if entering using http.
    	key: keyPath,
    	cert: certPath,
    	ca: caPath // optional
    	}
    }
```

---------------------------------------

<a name="unregister"/>

#### Redbird.unregister(src, [target])

 Unregisters a route. After calling this method, the given route will not
 be proxied anymore.

__Arguments__

```javascript
    src {String|URL} A string or a url parsed by node url module.
    target {String|URL} A string or a url parsed by node url module. If not
    specified, it will unregister all routes for the given source.
```

---------------------------------------

<a name="notFound"/>

#### Redbird.notFound(callback)

 Gives Redbird a callback function with two parameters, the HTTP request
 and response objects, respectively, which will be called when a proxy route is
 not found. The default is
```javascript
    function(req, res){
      res.statusCode = 404;
      res.write('Not Found');
      res.end();
    };
```
.

__Arguments__

```javascript
    src {Function(req, res)} The callback which will be called with the HTTP
      request and response objects when a proxy route is not found.
```

---------------------------------------

<a name="close"/>

#### Redbird.close()

 Close the proxy stopping all the incoming connections.

---------------------------------------