Create a new controllers directory and add a Controller class called ArticlesController in a file named articles_controller.rb as follows:

# controllers/articles_controller.rb

class ArticlesController
  attr_reader :env

  def initialize(env)
    @env = env
  end

  def index
    '<h1>All Articles</h1>'
  end
end

• The constructor accepts the env hash, storing it in an instance variable, so that all action methods can access it.
• It contains a single action called index which returns the response.

In the next lesson, we'll update the router to use this controller.