A stackable dynamic tree based Rack router.

Rack::Mount supports Rack's X-Cascade convention to continue trying routes if the response returns pass. This allows multiple routes to be nested or stacked on top of each other. Since the application endpoint can trigger the router to continue matching, middleware can be used to add arbitrary conditions to any route. This allows you to route based on other request attributes, session information, or even data dynamically pulled from a database.


Rack::Mount provides a plugin API to build custom DSLs on top of.

The API is extremely minimal and only 3 methods are exposed as the public API.


builder method for adding routes to the set


Rack compatible recognition and dispatching method


generates a route condition from identifiers or significant keys


require 'rack/mount'

Routes = Rack::Mount::RouteSet.new do |set|
  # add_route takes a rack application and conditions to match with
  # valid conditions methods are any method on Rack::Request
  # the values to match against may be strings or regexps
  # See Rack::Mount::RouteSet#add_route for more options.
  set.add_route FooApp, { :request_method => 'GET', :path_info => %r{^/foo$} }, {}, :foo

# The route set itself is a simple rack app you mount
run Routes

# generate path for route named "foo"
Routes.generate(:path_info, :foo) #=> "/foo"