Kubernetes specifically is in go because google invented go and also invented Kubernetes. Their internal teams have a lot of go engineers due to the whole inventing it thing
It was originally written in Java.
In fact, most Go users are outside Google, internally it is all about Java, Kotlin, Dart, C++ and Python, and now Rust as well.
Kubernetes, gVisor and Android GPU debugger are probably the only major internal projects in Go.
> We've incorporated the best ideas from Borg in Kubernetes, and have tried to address some pain points that users identified with Borg over the years.
Borg was written in C++, but only contained container scheduling, resource allocation and some service discovery. Many other features of what is now Kubernetes were built later and essentially "shimmed" onto Borg.
Kubernetes was a re-write of Borg to rebuild many of its original features from the ground up using the lessons they had learned since originally building Borg. By this time, Go had been developed and was being actively used for many of these shims and supporting services surrounding Borg. Since the same team(s) were rebuilding Borg that had developed and maintained these other services, and because many of these shims and supporting services (which are already in Go) were being incorporated into Kubernetes, they decided to build the new version (which became Kubernetes) in Go.
Sources:
- https://kubernetes.io/blog/2015/04/borg-predecessor-to-kuber...
- https://storage.googleapis.com/gweb-research2023-media/pubto...