Google has open sourced Seesaw, a Linux-based load balancing system written with Go programming language.
Some time ago, Google used two different load balancing systems, but after registering both management and stability issues, they decided to develop their own solution: Seesaw.
This software enables to "increase service availability and reduce management" overhead, explains Joel Sing, Google Site Reliability Engineer
Seasaw handles traffic for unicast and anycast VIPs, performs load balancing with NAT and performs health checks against the backends.
The code is already avaliable on GitHub under Apache license: Google/Seesaw code