Github user jtstorck commented on the issue:
https://github.com/apache/nifi/pull/3129
https://github.com/jtstorck/proxy-nifi-docker can be used to test this PR.
There's an issue in NiFi with the handling of X-Forwarded-Host when Knox is
proxying NiFi, which doesn't currently account for the port being present in
that header. I'll update the code to handle this case, and update the PR.---
