This repository contains the source code for a Go implementation of the Cloud Foundry router.

This router is now used on CloudFoundry.com, replacing the old implementation.

The original router can be found at cloudfoundry/router. The original router is backed by nginx, that uses Lua code to connect to a Ruby server that -- based on the headers of a client's request -- will tell nginx whick backend it should use. The main limitations in this architecture are that nginx does not support non-HTTP (e.g. traffic to services) and non-request/response type traffic (e.g. to support WebSockets), and that it requires a round trip to a Ruby server for every request.

The Go implementation of the Cloud Foundry router is an attempt in solving these limitations. First, with full control over every connection to the router, it can more easily support WebSockets, and other types of traffic (e.g. via HTTP CONNECT). Second, all logic is contained in a single process, removing unnecessary latency.

The following instructions may help you get started with gorouter in a standalone environment.

git clone https://github.com/cloudfoundry/gorouter.git
cd gorouter
git submodule update --init
./bin/go install router/router
gem install nats

# Start NATS server in daemon mode
nats-server -d

# Start gorouter
./bin/router

When gorouter is used in Cloud Foundry, it receives route updates via NATS after sending router.start. Routes that haven't responded with router.register in 2 minutes (configurable) are pruned unless connection to NATS was lost.

Therefore, to maintain an active route, it needs to be updated at least every 2 minutes. The format of these route updates are as follows:

{
  "host": "127.0.0.1",
  "port": 4567,
  "uris": [
    "my_first_url.vcap.me",
    "my_second_url.vcap.me"
  ],
  "tags": {
    "another_key": "another_value",
    "some_key": "some_value"
  }
}

Such a message can be sent to both the router.register subject to register URIs, and to the router.unregister subject to unregister URIs, respectively.

$ nohup ruby -rsinatra -e 'get("/") { "Hello!" }' &
$ nats-pub 'router.register' '{"host":"127.0.0.1","port":4567,"uris":["my_first_url.vcap.me","my_second_url.vcap.me"],"tags":{"another_key":"another_value","some_key":"some_value"}}'
Published [router.register] : '{"host":"127.0.0.1","port":4567,"uris":["my_first_url.vcap.me","my_second_url.vcap.me"],"tags":{"another_key":"another_value","some_key":"some_value"}}'
$ curl my_first_url.vcap.me:8080
Hello!

Gorouter provides /varz and /healthz http endpoints for monitoring.

The /routes endpoint returns the entire routing table as JSON. Each route has an associated array of host:port entries.

All of the endpoints require http basic authentication, credentials for which can be acquired through NATS. The port, user and password (pass is the config attribute) can be explicitly set in the gorouter.yml config file's status section.

status:
  port: 8080
  user: some_user
  pass: some_password

Example interaction with curl:

curl -vvv "http://someuser:somepass@127.0.0.1:8080/routes"
* About to connect() to 127.0.0.1 port 8080 (#0)
*   Trying 127.0.0.1...
* connected
* Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0)
* Server auth using Basic with user 'someuser'
> GET /routes HTTP/1.1
> Authorization: Basic c29tZXVzZXI6c29tZXBhc3M=
> User-Agent: curl/7.24.0 (x86_64-apple-darwin12.0) libcurl/7.24.0 OpenSSL/0.9.8r zlib/1.2.5
> Host: 127.0.0.1:8080
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Type: application/json
< Date: Mon, 25 Mar 2013 20:31:27 GMT
< Transfer-Encoding: chunked
< 
{"0295dd314aaf582f201e655cbd74ade5.cloudfoundry.me":["127.0.0.1:34567"],"03e316d6aa375d1dc1153700da5f1798.cloudfoundry.me":["127.0.0.1:34568"]}

The router's logging is specified in its YAML configuration file, in a steno configuration format. The meanings of the router's log levels are as follows:

• fatal - An error has occurred that makes the current request unservicable. Examples: the router can't bind to its TCP port, a CF component has published invalid data to the router.
• warn - An unexpected state has occurred. Examples: the router tried to publish data that could not be encoded as JSON
• info, debug - An expected event has occurred. Examples: a new CF component was registered with the router, the router has begun to prune routes for stale droplets.

• 03/05/13: Code is now used on CloudFoundry.com.

• 1/25/13: The code in this repository has not yet been used on CloudFoundry.com.

• 1/25/13: While this implementation can easily support WebSocket connections it does not yet.