I'm still unconvinced Docker's choice of using Go is the primary culprit for their problems. If Docker had started bottom up they would have been forced to design tighter contracts between the components from the beginning (regardless of language).

Ultimately it's the architectural decision to couple everything that allowed them to be loosey-goosey with internal-only interfaces. Why bother specifying them thoroughly if you can update all components simultaneously and have no dependencies outside of your control? I'm sure a tighter language would have helped in the small, but their problems are categorically big problems that I believe transcend smaller and more localized failings.

My experience using Consul for the Vault backend has been pretty good. Yes, you have to manually go in and clean up old nodes after a restart, but that isn't too bad. So far (knock on wood) we haven't run into a situation where a replacement node has refused to join the cluster or the cluster has out-right failed.

That said, I do wish they would put the effort to properly integrate with Etcd. We've gone through the motions of setting up and managing a highly-available Etcd cluster for quite some time now and are more confident running it than Consul. I'd rather standardize on Etcd myself, but I'm not inclined to swim upstream. :)