1. we depended on half the Go ecosystem at one point (docker, grpc, etcd, a few others) which is hard to do with dependencies in go (few standardized libraries)
2. performance of serialization mattered and JSON and protobuf were still raw at the time
I don't think Kubernetes is any worse than any other large (3M+ LOC), relatively young codebase I've seen on average.
Most of the codebase problems in Kube are:
1. we depended on half the Go ecosystem at one point (docker, grpc, etcd, a few others) which is hard to do with dependencies in go (few standardized libraries)
2. performance of serialization mattered and JSON and protobuf were still raw at the time
I don't think Kubernetes is any worse than any other large (3M+ LOC), relatively young codebase I've seen on average.