example proxy config.ru to foreward ajax request to different domain (CORS - workaround)

config.ru

# Rack app to proxy ajax request to server on different domain (CORS).
# This is usefull if you have a rails-api and a backbone frontend on different domains
# and you want an easy solution to develop both apps on your local mashine with pow.

# Put this file in your backbone/angular/javascript folder. 
# The assets should be in the ./public folder

# extend the REGEX to match a path you want to redirect.
# @redirect_regex = /\/api/

# change the API url
# @api_url = 'example.com'

require 'logger'
require 'rack-proxy'
require 'json'

class AppProxy < Rack::Proxy

  def initialize
    super
    @logger = Logger.new('./log/rack.log')
    @api_url = 'example.com'
    @redirect_regex = /\/api/
  end

  def log(string)
    @logger.info("#{string}")
  end
  
  def env_log env
    log "#{env['REQUEST_METHOD']} #{env['PATH_INFO']}"
  end

  def api_url(env)
    subdomain = env['HTTP_HOST'].split(".").first
    url = "#{subdomain}.#{@api_url}"
    return url
  end

  def rewrite_env(env)
    env_log env
    match = env["PATH_INFO"].match @redirect_regex
    if match && match.length > 0
      env["HTTP_HOST"] = api_url(env)
    end
    env
  end

end

run AppProxy.new