One of the major issues with an external variable registry file which we refer to in the nifi.properties file is that it needs NiFi instance to be bounced. While this may serve your purpose in the lower environments in a purpose, at an enterprise level cluster this might not be feasible in higher environments like Production. What this also means is that due to lack of common global variables/parameters, you may need to spin up a new controller service every time. I think a Configuration service is a must and should be worked upon. :)
-- Sent from: http://apache-nifi-developer-list.39713.n7.nabble.com/
