mastodon/app/controllers/application_controller.rb

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception

  # Profiling
  before_action do
    if (current_user && current_user.admin?) || Rails.env == 'development'
      Rack::MiniProfiler.authorize_request
    end
  end
end