Sorry, the Sinatra based site is deployed with "ruby app.rb". Probably not enough...
Since you are running it as "ruby app.rb", I take it you aren't interested in doing an app server/web server/cache deployment. But if you aren't using thin, that's only a "gem install thin" away.
http://uwsgi-docs.readthedocs.org/en/latest/Ruby.html#runnin...