Rails routes.rb constraints
Got it:

Rails.application.routes.draw do
  root 'home#index'

  resources :articles, except: [:index, :show]
  constraints section: /section1|section2|section3|section4/ do
    constraints year: /\d{4}/ do
      constraints month: /\d{1,2}/ do
        resources :articles, only: [:index, :show], path: '/:section/:year/:month', as: :my_articles
        get ':section/:year/:month', to: 'articles#by_month', as: :month
      end
      get ':section/:year', to: 'articles#by_year', as: :year
    end
    get ':section', to: 'articles#by_section', as: :section
  end


I feel this is much cleaner :)