Subdomain routes for multiple controllers

routes.rb

MyApp::Application.routes.draw do
  resources :agents do
    resources :brands, module: 'agents'
  end

  get '/', to: 'agents/brands#show', constraints: lambda { |r| r.subdomain.present? && r.subdomain != 'www' }
  get '/', to: 'agents#show', constraints: lambda { |r| r.subdomain.present? && r.subdomain != 'www' }

  root 'home#index'
end