Deploy static pages to domain root and rails application to subdomain - ruby-on-rails

Question

I'm following Michael Hartl's Rails Tutorial and deploying to Heroku.
I have static pages that are public to every web visitor and dynamic and "protected" pages that require the user to sign in in order to view them. Currently all pages are deployed to the website's root: example.com/static-page and example.com/users/1/
My objective:
deploy static pages to the root, like example.com/static-page
deploy rails' pages to a subdomain, like app.example.com/users/1
I assume the solution involves changing the routes file. Is there any tutorial or video explaining how to do so? I'm a newbie on Rails.
My routes file:
Dcid::Application.routes.draw do
resources :users
resources :sessions, only: [:new, :create, :destroy]
root 'static_pages#home'
match '/home', to: 'static_pages#home', via: 'get'
match '/about', to: 'static_pages#about', via: 'get'
match '/signup', to: 'users#new', via: 'get'
match '/signin', to: 'sessions#new', via: 'get'
match '/signout', to: 'sessions#destroy', via: 'delete'

Answer 1

You could either have a controller serving your pages or simply put your HTML files in public an treat them as assets.
In either case if they are really static, you might want to cache heavily or put a CDN in front of everything.

Answer 2

You'll want something like this:
#config/routes.rb
root 'static_pages#home'
#Subdomain
constraints subdomain: 'app' do
resources :users
end
#Pages
pages = %w(home about)
for page in pages do
get "/#{page}", to: "static_pages##{page}"
end
#Resources
resources :users do
get :new, as: :collection
end
resources :sessions, only: [:new, :create, :destroy] do
get :signin, action: :new, as: :collection
delete :signout, to: :destroy, as: :collection
end
This will create the routes you need. However, you won't be able to use a subdomain on Heroku, unless you use a custom domain