Sinatra: How to use "settings" to inject dependencies

boot.rb

# Setup the Service::Api
Service::Api.set(:environment, :production)
Service::Api.set(:root, Service.root)
Service::Api.set(:service, Service::Provider.new)

config.ru

#!/usr/bin/env rackup
# encoding: utf-8

$stdout.sync = true

require "boot"

run Rack::URLMap.new('/' => Service::Api)

provider.rb

require "sinatra/base"

module Service
  class Provider
    def get_data
       {:root => "hello, world"}
    end
  end
end

service.rb

require "sinatra/base"

module Service
  class Api < Sinatra::Base
    before do
      content_type :json
    end

    get "/" do
      settings.service.get_data.to_json
    end
  end
end