Ask HN: Do you run databases on Kubernetes?

For the specific incident I mentioned in the original post, I didn't quite get the exact details of the problem, but I think the gist of it was that our MongoDB deployment was using too much memory for its cache. We're running it on our Kubernetes cluster that use M5.xlarge EC2 nodes, and it was causing problems to other applications deployed on the same node. Kubernetes was, understably, having a hard time managing resource and scheduling the deployments.

I think one of the challenges with running databases on Kubernetes is that, at the time of writing, Kubernetes does not really have an abstraction for databases and so it manages them just like any other resource (of a given type). Operators are meant to address this though, and the people at Kubecon seem to be excited about it, but I haven't used it personally.

Yeah, sounds like operators really are a perfect fit for this use case. For your e2e, I imagine you use the operators to spin up new database instances for every run? I really like the idea of being able to do that, which is something I imagine would be difficult outside of Kubernetes.

For production though, do you have any specific scheduling logic to ensure that database resources don't cause issues with other services in the cluster, or is it just a matter of configuring the database service?

> unless you use a host only PV and if you do that you are likely limiting you db instamce to a specific node which can have scaling and/or HA impacts

This is exactly what we do, and we're having trouble because of it and not only in terms of scaling the database, but also because it runs on the same node as all other Kubernetes resources. We are considering spinning up a dedicated node for it, but I thought at that point we should probably just buy an actual dedicated database solution instead; buy the expertise we don't have currently.

Yeah, this is one of the things we are considering at the moment. However, if I understand correctly, for MongoDB specifically, you need to be using their enterprise offering to be able to utilize their operator.