I'd be very interested to hear if you've come across any good documentation on hardening Kubernetes?
From what I've seen so far there's very limited documentation on that when compared to other components like Docker, and the defaults can sometimes not be suitable for a high security environment (e.g. https://raesene.github.io/blog/2016/10/08/Kubernetes-From-Co... )
As such there needs to be a level of hardening done from an out of the box perspective where they're being used in a high-security environment (e.g. banking).
For Docker we have resources like docker_bench and the CIS guide which provide a list of possible hardening steps, but I've not managed to find anything like that for Kubernetes, which is why I'm interested in how Monzo are addressing that issue.
[1] https://www.twistlock.com/
[2] https://cloudplatform.googleblog.com/2015/11/enhancements-to...