(defn parse-graphite-service
  "Riemann puts the entire graphite metric in the service field, and leaves
   host empty.
   Parse the input graphite metric to extract information send it to multiple
   streams."
   [service]
   ( let [[top_level_namespace hostname srv ] (re-find #"^(sys)\.(\w+)\.(.+)$" service)] [top_level_namespace hostname srv]
   )
)

user=> (def s "sys.foo.bar.baz")
#'user/s
user=> (def not-s "foo.bar.baz")
#'user/not-s

user=> (parse-graphite-service not-s)
[nil nil nil]
user=> (parse-graphite-service s)
["sys.foo.bar.baz" "sys" "foo"]