Constrain a route to a specific host

If you have two hosts that point to one rails app, like apple.myapp.com and orange.myapp.com and you'd like a specific route to only be availabe on orange then you can constrain the route based on the host like this:

constaints(host: 'orange.myapp.com') do
  get '/thing/:id', to: 'thing#show'
end

And if you had additional host for banana that should also get this route:

constaints(host: ['orange.myapp.com', 'banana.myapp.com']) do
  get '/thing/:id', to: 'thing#show'
end

But in this case only the subdomain differs so we can do this:

constaints(subdomain: ['orange', 'banana']) do
  get '/thing/:id', to: 'thing#show'
end