What people tend to do is to handle exception in controller with rescue_from, well it is totally fine. However there is also a different way by delegating the handling to router.

Configure the app to handle exception with Router

# config/application.rb

config.exceptions_app = self.routes

Tell Router how to handle error by matching status code

# config/routes.rb

Rails.application.routes.draw do
  constraints Router::Error do
    match '404' => 'errors#not_found', :via => :all
    match '406' => 'errors#not_acceptable', :via => :all
    match '410' => 'errors#gone', :via => :all
    match '500' => 'errors#internal_server_error', :via => :all
  end
end

Your are free to do whatever with your ErrorsController

# app/controllers/errors_controller.rb

class ErrorsController < ActionController::Base
  def not_acceptable
    respond_to do |format|
      format.any { render :nothing => true, :status => 406 }
    end
  end

  def not_found
    respond_to do |format|
      format.any(:json, :xml, :atom) { render :text => "Error: Page Not Found", :status => 404 }
    end
  end

  def gone
    respond_to do |format|
      format.any(:json, :xml, :atom) {
        render :text => "The page is gone", :status => 410
      }
    end
  end
  
  def internal_server_error
    # do whatever you like - you get the idea
  end
end