The metrics_vmstat.rb plugin inherits a lot of its functionality from Sensu::Plugin::Metric::CLI::Graphite
. You might try having your plugin inherit from the same class.
Alternatively, since Sensu and Graphite both use amqp, you can configure sensu-server to route the metrics for you. Check out method 2 in Joe Miller's blog post (http://joemiller.me/2012/02/02/sensu-and-graphite/), that should help get you started.