特定のドメインへのリクエストをローカルに転送

proxy.rb

# -*- coding: utf-8 -*-
#!/usr/bin/env ruby

require 'webrick'
require 'webrick/httpproxy'
require 'uri'
require 'open-uri'

handler = Proc.new() do |req, res|
  if req.host == 'target.example.com'
    open "http://127.0.0.1:3000#{req.path}"
  end
end

server = WEBrick::HTTPProxyServer.new(
  BindAddress: '127.0.0.1',
  Port: 8080,
  Logger: WEBrick::Log::new($stderr, WEBrick::Log::DEBUG),
  ProxyVia: false,
  ProxyContentHandler: handler
)

Signal.trap('INT') do
  server.shutdown
end

server.start