Heroku Cedar static file server with rack

config.ru

require "rubygems"
require 'rack'
require 'rack-rewrite'

use Rack::Static, :urls => ['/images'], :root => "public"
use Rack::Rewrite do
  rewrite '/', '/index.html'
end
run Rack::Directory.new('public')

Gemfile

source :rubygems
gem "rack", "~> 1.4"
gem "rack-rewrite", "~> 1.2.1"
gem "thin"

Gemfile.lock

GEM
  remote: http://rubygems.org/
  specs:
    daemons (1.1.8)
    eventmachine (0.12.10)
    rack (1.4.1)
    rack-rewrite (1.2.1)
    thin (1.4.1)
      daemons (>= 1.0.9)
      eventmachine (>= 0.12.6)
      rack (>= 1.0.0)

PLATFORMS
  ruby

DEPENDENCIES
  rack (~> 1.4)
  rack-rewrite (~> 1.2.1)
  thin