I can curl results just fine either from graylog.mysite.fi(:80) or directly from node like 10.1.31.55:9000. Which setting have I misconfigured?
some of the relevant configs:
Huh, odd because I have the same setup on my 3 node cluster, and I loadbalance with nginx - and the API browser works for me. You may want to check that all nodes have the proper http_bind_address and external_uri settings and that your loadbalancer adds the X-Graylog-Server header properly (in 2.5 you had to add /api to the end, in 3.0 you have to leave it off).
I commented that line out and restarted nodes, now I can use REST API also from webUI.
Maybe I somehow misunderstood the server.conf changes/guide… That the new config is that much less complicated