Getting geo location into nginx access log

I would like to get the already configured maxminddb data also into the nginx access log when running discourse.

Currently I have the 2.8.0.beta9 up and running, maxmindDB is configured and works for interactive lookups.

But the access log should include (optionally) some of those geo ip values.
It will add some overhead to the loggin gperhaps, but as the data is locally existing it should be only a minor effort.

Or this this already working somehow?