If you don't provide proxy options Net::HTTP::Proxy should fall back to a Net::HTTP class acording to http://ruby-doc.org/stdlib-1.9.3//libdoc/net/http/rdoc/Net/HTTP.html#method-c-Proxy 
This line has been inspired by newrelic's ruby agent gem proxy handling : https://github.com/smtlaissezfaire/newrelic_new_mirror/blob/master/lib/new_relic/control.rb#L215