Rails: possible to restrict a route based on IP address (or range?)

Question

I know this usually happens in the controller but I'm wondering if it's possible in config/routes.rb to restrict a route based on a specific IP (or range of IPs)? Sort of a whitelist, of sorts.

for example I'd like to restrict this route to only IPs on our subnet:

#config/routes.rb
require 'sidekiq/web'

MyApp::Application.routes.draw do
  resources :users
  ...
  mount Sidekiq::Web, at: "/sidekiq"      # <== restrict this based on IP address
  ...
end

Answer 1

Based on the example from the Rails Docs you could do:

#config/routes.rb
require 'sidekiq/web'

MyApp::Application.routes.draw do
  resources :users
  ...
  mount Sidekiq::Web, at: "/sidekiq", :constraint => Whitelist.new
  ...
end

class Whitelist
  def initialize
    @ips = Whitelist.retrieve_ips
  end

  def matches?(request)
    @ips.include?(request.remote_ip)
  end

  def retrieve_ips
    # get and return your whitelist of ips
  end
end

This post by Yehuda Katz goes into more detail on constraints and how to use them.