middleware to allow set rails session subdomain wide, need when application is mulity domain. tested on rails 2.3.5

set_cookie_domain.rb

# hack to allow config.action_controller.session[:domain] option be not hardcoded
# since our app have different first level domains
# original solution found here: http://codetunes.com/2009/04/17/dynamic-cookie-domains-with-racks-middleware/
class SetCookieDomain
  def initialize(app)
    @app = app
  end

  def call(env)
    # keep from custom.domain.com:3000, only domain.com 
    domain = env["HTTP_HOST"].sub(/.*\.([[:alnum:]-]+\.\w+)(:\d+)?$/, '\1')
    env["rack.session.options"][:domain] = ".#{domain}"
    @app.call(env)
  end
end