API versioning with constraints

routes.rb

namespace :api do
  constrants ApiVersion.new(1) do
    scope :module => :v1 do
      resource :app do
        resources :indices
      end
    end
  end

  constraints ApiVersion.new(2) do
    scope :module => :v2
      resource :app do
        resources :indices
      end
    end
  end
  
  match "/*path", to: "errors#unsupported_version", via: :all
end