Contributed Rack Middleware and Utilities

This package includes a variety of add-on components for Rack, a Ruby web server interface:

  • Rack::JSONP - Adds JSON-P support by stripping out the callback param and padding the response with the appropriate callback format.

  • Rack::LighttpdScriptNameFix - Fixes how lighttpd sets the SCRIPT_NAME and PATH_INFO variables in certain configurations.

  • Rack::Locale - Detects the client locale using the Accept-Language request header and sets a rack.locale variable in the environment.

  • Rack::MailExceptions - Rescues exceptions raised from the app and sends a useful email with the exception, stacktrace, and contents of the environment.

  • Rack::NestedParams - parses form params with subscripts (e.g., * “post=Hello”) into a nested/recursive Hash structure (based on Rails' implementation).

  • Rack::PostBodyContentTypeParser - Adds support for JSON request bodies. The Rack parameter hash is populated by deserializing the JSON data provided in the request body when the Content-Type is application/json.

  • Rack::ProcTitle - Displays request information in process title ($0) for monitoring/inspection with ps(1).

  • Rack::Profiler - Uses ruby-prof to measure request time.

  • Rack::Sendfile - Enables X-Sendfile support for bodies that can be served from file.

  • Rack::Signals - Installs signal handlers that are safely processed after a request

  • Rack::StaticCache - Modifies the response headers to facilitiate client and proxy caching for static files that minimizes http requests and improves overall load times for second time visitors.

  • Rack::TimeZone - Detects the client's timezone using JavaScript and sets a variable in Rack's environment with the offset from UTC.

  • Rack::Evil - Lets the rack application return a response to the client from any place.

  • Rack::Callbacks - Implements DSL for pure before/after filter like Middlewares.

  • Rack::Config - Shared configuration for cooperative middleware.

  • Rack::NotFound - A default 404 application.

  • Rack::CSSHTTPRequest - Adds CSSHTTPRequest support by encoding responses as CSS for cross-site AJAX-style data loading

  • Rack::Deflect - Helps protect against DoS attacks.

  • Rack::ResponseCache - Caches responses to requests without query strings to Disk or a user provider Ruby object. Similar to Rails' page caching.

  • Rack::RelativeRedirect - Transforms relative paths in redirects to absolute URLs.

  • Rack::Backstage - Returns content of specified file if it exists, which makes it convenient for putting up maintenance pages.

  • Rack::AcceptFormat - Adds a format extension at the end of the URI when there is none, corresponding to the mime-type given in the Accept HTTP header.

  • Rack::HostMeta - Configures /host-meta using a block

  • Rack::Cookies - Adds simple cookie jar hash to env

  • Rack::Access - Limits access based on IP address

  • Rack::ResponseHeaders - Manipulates response headers object at runtime

  • Rack::SimpleEndpoint - Creates simple endpoints with routing rules, similar to Sinatra actions

  • Rack::TryStatic - Tries to match request to a static file

  • Rack::Printout - Prints the environment and the response per request


Git is the quickest way to the rack-contrib sources:

git clone git://

Gems are available too:

gem install rack-contrib

Requiring 'rack/contrib' will add autoloads to the Rack modules for all of the components included. The following example shows what a simple rackup ( file might look like:

require 'rack'
require 'rack/contrib'

use Rack::Profiler if ENV['RACK_ENV'] == 'development'

use Rack::ETag
use Rack::MailExceptions

run theapp


To contribute to the project, begin by cloning the repo and installing the necessary gems:

gem install json rack ruby-prof test-spec test-unit

To run the entire test suite, run

rake test

To run a specific component's tests run

specrb -Ilib:test -w test/spec_rack_thecomponent.rb

This works on ruby 1.8.7 but has problems under ruby 1.9.x.

TODO: instructions for 1.9.x and include bundler

rack-contrib on GitHub




Rack On GitHub


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