config.ru

require "rails"
require "action_controller/railtie"

class SampleFile < Rails::Application
  config.secret_key_base = "pa34u13hsleuowi1aisejkez12u39201pluaep2ejlkwhkj"

  routes.append do
    root to: 'foo#index'
    get 'foo/bar'
  end

  initialize!
end

class FooController < ActionController::Base
  include Rails.application.routes.url_helpers

  def index
    redirect_to controller: :foo, action: :bar, status: 'FOO'
  end

  def bar
    render text: "HEY #{params[:status]}"
  end
end

run Rails.application