We don't put any persistent data into Kube. Everything goes into OpenStack instances (Ubuntu), orchestrated by Chef. We hate it. OpenStack SDN has been flaky, Chef is a pain and doesn't support the latest Ubuntu releases well, none of the devs or technical ops engineers like it.
It's my #1 goal for 2017: figure out persistent volumes for Kube.
Change Chef for Ansible and I have the same architecture. And you know what? I have decided to put on hold K8S until persistence is properly managed.
Meanwhile, we have decided to give a chance to serverless architectures with AWS lambda.
I agree that persistence in k8s is tricky, especially at scale, but at least in our case that doesn't drive us way from the platform. Kube is awesome for services, and if we have to keep a few things on gcloud instances bolted to reliable storage for the moment that's at least less heterogeneous than what we had before kube came along. In other words I don't think you have to kube all the things to see a lot of benefit.
Are you running Openstack yourself or a vendor backed version ? My understanding is deploying OpenStack in production is a nightmare. Would you mind sharing your experience (cluster size, upgrade, support etc.) ?
Disclaimer I work at Pivotal but - I'd suggest taking a look at http://bosh.io which can handle full stack automation ; there already are quality releases for MySQL, elastic, mongo (from anynines), and Cassandra, with commercially supported releases in some cases with fully orchestrated vm and volume management on Openstack.
These are for cloud foundry nominally but (yay actually collaborating foundations) the open service broker API ( https://www.openservicebrokerapi.org/ ) allows you to hook these into Kube and (the best part) standardize how your CI/CD pipelines manage the lifecycle of these services independently of whether they're backed by Openstack today or Kubernetes tomorrow.
Persistent volumes for these sorts of services on Kube will require the new PetSet primitive to mature.
It's my #1 goal for 2017: figure out persistent volumes for Kube.