Facebook's Katran looked too scary (and I don't do C++), so I thought I would investigate using XDP/eBPF to redirect packets at high speed and Go to do the control plane work of health-checking backed servers and managing configuration. With luck the resulting binary should be easy to deploy by non-developers.
It's still not mature, but seems to work. Code was written in a very exploratory manner, and I'm not a developer so it is quite shocking at the moment, but I aim to improve it. It is intended to be horizontally scalable with ECMP and has been tested on service providing 40Gb/s with a single (hardware) node at ~30% CPU utilisation.