It makes me sad that to get these scalability numbers requires some secret sauce on top of spanner, which no body else in the k8s community can benefit from. Etcd is the main bottleneck in upstream k8s and it seems like there is no real steam to build an upstream replacement for etcd/boltdb.

I did poke around a while ago to see what interfaces that etcd has calling into boltdb, but the interface doesn’t seem super clean right now, so the first step in getting off boltdb would be creating a clean interface that could be implemented by another db.