Supplements http://blog.bignerdranch.com/4733-adding-versions-rails-api

articles_controller.rb

# https://github.com/iamvery/rails-api-example/blob/b21a0a918c65892376ccbebaf96057051795afc0/app/controllers/v1/articles_controller.rb
module V1
  class ArticlesController < ApplicationController
    def index
      articles = [
        { id: 123, name: 'The Things' },
      ]

      respond_to do |format|
        format.json do
          render json: articles
        end
      end
    end
  end
end