Serving PHP apps locally with with pow and rack-legacy http://stuff-things.net/2011/05/16/legacy-development-with-pow/

config.ru

require 'rack'
require 'rack-legacy'
require 'rack-rewrite'

INDEXES = ['index.html','index.php', 'index.cgi']

use Rack::Rewrite do
  rewrite %r{(.*/$)}, lambda {|match, rack_env|
    INDEXES.each do |index|
      if File.exists?(File.join(Dir.getwd, rack_env['PATH_INFO'], index))
        return rack_env['PATH_INFO'] + index
      end
    end
    rack_env['PATH_INFO']
  }
end

use Rack::Legacy::Php, Dir.getwd
use Rack::Legacy::Cgi, Dir.getwd
run Rack::File.new Dir.getwd

php.Gemfile

source 'https://rubygems.org'

gem 'Rack-legacy'
gem 'rack-rewrite'