How to build the simplest static site with Rails (yes I know you can put files in public and call that simpler. This uses the framework)

about.html.erb

<p>Hi! I'm an about page. Edit me in views/static_pages/</p>

constants.rb

# Add to config/initializers
ALLOWED_STATIC_PAGES = Dir.entries("#{Rails.root}/app/views/static_pages").map {|file| file if file.include?('erb')}.compact

routes.rb

# Example route
get '/about', to: 'static_pages#show', page: 'about'

static_pages_controller.rb

class StaticPagesController < ApplicationController
  def show
    if valid_page?
      render template: "static_pages/#{params[:page]}"
    else
      render file: "public/404.html", status: :not_found
    end
  end

  private

  def valid_page?
    ALLOWED_STATIC_PAGES.include? "#{params[:page]}.html.erb"
  end
end