In our environment:
Graphite is installed on the same servers as grafana.
Graphite runs under gunicorn and presents as an http unix socket as does grafana. Nginx fronts both. Grafana accesses graphite using http over tcp via nginx.
It occurs to me that accessing graphite directly via unix socket is a more optimal route.
I have tried playing with the graphite data source but can not get it to work. Syntax validation in the URL field even goes red.
This is far from essential for us but i am interested to hear if anybody has a data source working like this. If it is simple to add as a feature - that would be cool.