config.ru

require "warden"

class App
  def call(env)
    env['warden'].authenticate!
    [200, {'Content-Type' => 'text/plain'}, ['OK']]
  end
end

Warden::Strategies.add(:password) do
  def valid?
    params["username"] && params["password"]
  end

  def authenticate!
    if params["username"] == "admin" and params["password"] == "admin"
      success!("success")
    else
      fail!
    end
  end
end

use Rack::Session::Cookie, :secret => "replace this with some secret key"

use Warden::Manager do |manager|
  manager.default_strategies :password
  manager.failure_app = ->(env) {[401, {}, ['Unauthorized']]}
end

run App.new