Although the main interface between applications and a Vitess database is through the MySQL protocol, Vitess is a large and complex distributed system, and all the communication between the different services in a Vitess cluster is performed through GRPC. Because of this, all service boundaries and messages between Vitess' systems are specified using Protocol Buffers. The history of Vitess' integration with Protocol Buffers is rather involved: We have been using and keeping up to date with the Go Protocol Buffers package since its earliest releases, up until May last year, when Google released a new Go API for Protocol Buffers, which is not backwards compatible with the previous Go package.
Cross posting link Golang is a wonderful language. It's simple, and most of the time not confusing or surprising. This makes it easy to jump into library code and start reading and quickly understand what's going on. On the other hand, coming from other languages, there are a few features that would make our lives easier. We are building Vitess using mostly golang, and most of us are happy with this choice.