ESI middleware implementation for Rack. This middleware is currently reimplemented to run commands in parallel and fetch with curb.
Latest commit bff49e4 Jan 13, 2014 @boof Update
Mr Typo


Rack-ESI is a Nokogiri based ESI middleware implementation for Rack with support for include tags, all other ESI namespaced nodes are just removed.

To make this gem work you must define the xmlns:esi namespace in your text/html response.

Note: This gem should only be used in development. For production use setup varnish or any other ESI enabled server.


  • threaded (in case we have slow IOs)
  • PATH_INFO blacklisting (:skip => nil, should respond to ===)
  • support for esi|include[alt] and esi|include[noerror] fallbacks


  • Nokogiri
  • Rack


w/o Gemfile

$ gem install rack-esi

w/ Gemfile

gem 'rack-esi'

... and ...

$ bundle


use Rack::ESI, options || {}

Rails 2.3: environment.rb

... for setups w/o Gemfile

config.gem 'rack-esi'

... and ...

config.middleware.insert Rack::Lock, Rack::ESI

Rails 3.x: application.rb

config.middleware.insert ActionDispatch::Static, Rack::ESI

Rails 4.x: config/environments/development.rb

config.middleware.insert_before Rack::Lock, Rack::ESI


  • poolsize: 4, Number of worker threads. A value of 1 disables threading model.
  • skip: nil, This should be an object which responds to #===(PATH_INFO).
  • parser: Nokogiri::XML::Document, You can change this to Nokogiri::HTML::Document, but you should change the serializer, too (see below).
  • serializer: :to_xhtml, The serializer value specifies the method name which is send to the object created by the parser#parse.


  • write documentation
  • write more tests
  • support more ESI elements

Note on Patches/Pull Requests

  • Fork the project.
  • Make your feature addition or bug fix.
  • Add tests for it.
  • Commit, do not mess with rakefile, version, or history.
  • Send me a pull request.


tenderlove and Qerub


Copyright (c) 2011 Florian Aßmann. See LICENSE for details.