False dilemma. Ansible and Puppet are great tools for configuring kubernetes, kubernetes worker nodes, and building container images.
Kubernetes does not solve for host OS maintenance; though there are a number of host OS projects which remove most of what they consider to be unnecessary services, there's still need to upgrade kubernetes nodes and move pods out of the way first (which can be done with e.g. Puppet or Ansible).
As well, it may not be appropriate for monitoring to depend upon kubernetes; there again you have nodes to manage with an SCM tool.