gistfile1.rb

require 'rubygems'
require 'sinatra'
require 'warden'

Warden::Strategies.add(:password) do
  def authenticate!
    if params["login"] == "name"
      success!("the user")
    else
      fail!("Can't log you in")
    end
  end
end

Warden::Strategies.add(:nigel) do
  def authenticate!
    if params["login"] == "nigel"
      success!("the user")
    else
      fail!("You're not nigel")
    end
  end
end

Warden::Manager.before_failure do |env, opts|
  env['REQUEST_METHOD'] = "POST"
end

class ::MyMiddleware

  def initialize(app)
    @app = app
  end

  def call(env)
    request = Rack::Request.new(env)
    if request.path == "/custom"
      request.env["warden"].authenticate!
      Rack::Response.new("You're OK!").finish
    else
      @app.call(env)
    end
  end
end


class MyApp < Sinatra::Application
  use Rack::Session::Cookie

  use Warden::Manager do |manager|
    manager.default_strategies :password
    manager.failure_app        = self
  end

  use MyMiddleware

  helpers do
    def warden
      request.env['warden']
    end

    def require_login(*args)
      warden.authenticate!(*args)
    end
  end

  get "/authd" do
    require_login
    "Session: #{request.session}"
  end

  get "/public" do
    "Public"
  end

  get "/logout" do
    warden.logout
    redirect "/public"
  end

  post "/unauthenticated" do
    out = warden.message
    out << " You need to login"
    out
  end
end

MyApp.run!