I've been slowly ramping up with Nifi, and am trying to find some information on the ExtractGrok processor. I can't seem to find any actual examples anywhere on it's use and everything I'm trying is failing.
Specifically, I can't figure out exactly what to provide for the grok Expression vs the grok Pattern file; they would seem to be the kind of thing you'd provide one or the other but it wants both.
I'm simply trying to pull a few fields out of a log message (and there may be better ways to do it long term) but I'm really curious about how to make this processor work.
Does anyone have a real example of it's use I could reference?