Rails static pages generation/compilation with no extra routing or controllers.

static.rake

namespace :static do
  desc "Compile static pages and save them in /public"
  task compile: :environment do
    class StaticController < AbstractController::Base
      include AbstractController::Rendering
      include AbstractController::Layouts
      include AbstractController::Helpers
      include AbstractController::AssetPaths
      include Rails.application.routes.url_helpers

      helper ApplicationHelper
      def protect_against_forgery?; false; end
      def logged_in?; false; end
      helper_method :protect_against_forgery?, :logged_in?

      self.view_paths = Rails.application.config.paths['app/views']

      def show(template)
        render template: "static/#{template}", layout: 'application'
      end
    end

    Dir["#{Rails.root}/app/views/static/*.html.erb"].each do |path|
      template_name = File.basename(path, '.html.erb')
      static_path   = Rails.public_path.join("#{template_name}.html")

      File.open(static_path, 'w') do |f|
        f.write(StaticController.new.show(template_name))
      end
    end
  end
end