Sinatra metal with Rails authentification

api.rb

# Allow the metal piece to run in isolation
require(File.dirname(__FILE__) + "/../../config/environment") unless defined?(Rails)
require 'sinatra'

class Api < Sinatra::Application
  helpers do
    def protected!
      unless authorized?
        response['WWW-Authenticate'] = %(Basic realm="Restricted Area")
        throw(:halt, [401, "Not authorized\n"])
      end
    end

    def authorized?
      if env["rack.session"][:user]
        @current_user = User.find(env["rack.session"][:user])
      else
         @auth ||=  Rack::Auth::Basic::Request.new(request.env)
         if @auth.provided? && @auth.basic? && @auth.credentials
           @current_user = User.authenticate(*@auth.credentials)
         end
      end
    end

  end


  before do
    protected!  if request.path =~ /^\/api/
  end

  get '/api/test/' do
    @current_user.email
  end


end