Proxy Machine 是一个简单的 7 层 TCP 路由代理，基于 EventMachine 构建，可使用 Ruby 语言配置路由规则。如果你需要将不同的请求内容转发到后端不同的服务器上，那么 ProxyMachine 非常适合你。
ProxyMachine 主要为 Github 的集群架构而开发，每天可代理几百万请求，性能和内存占用表现良好。
安装：
$ gem install proxymachine -s http://gemcutter.org
使用方法：
Usage:
proxymachine -c <config file> [-h <host>] [-p <port>]
Options:
-c, --config CONFIG Configuration file
-h, --host HOST Hostname to bind. Default 0.0.0.0
-p, --port PORT Port to listen on. Default 5432
示例配置：
class GitRouter
# Look at the routing table and return the correct address for +name+
# Returns "<host>:<port>" e.g. "ae8f31c.example.com:9418"
def self.lookup(name)
...
end
end
# Perform content-aware routing based on the stream data. Here, the
# header information from the Git protocol is parsed to find the
# username and a lookup routine is run on the name to find the correct
# backend server. If no match can be made yet, do nothing with the
# connection.
proxy do |data|
if data =~ %r{^....git-upload-pack /([\w\.\-]+)/[\w\.\-]+\000host=\w+\000}
name = $1
{ :remote => GitRouter.lookup(name) }
else
{ :noop => true }
end
end
