discourse/app/controllers/offline_controller.rb

# frozen_string_literal: true

class OfflineController < ApplicationController
  layout false
  skip_before_action :preload_json,
                     :check_xhr,
                     :redirect_to_login_if_required,
                     :redirect_to_profile_if_required

  def index
    render :offline, content_type: "text/html"
  end
end