<p>I know that I can <a href="https://kubernetes.io/docs/tasks/administer-cluster/memory-default-namespace/#create-a-limitrange-and-a-pod" rel="nofollow noreferrer">create a LimitRange</a> in a namespace. Then all pods created in <em>that</em> namespace will have Resource (CPU/Memory) Limits/Requests set.</p>

<p>So my initial question of how to enforce Resource Limits/Requests on all resources in a kubernetes cluster seems to be equivalent to: How do I enforce a LimitRange exists in every namespace?</p>

<p>It is currently not possible to enforce <code>LimitRange</code> and <code>ResourceQuota</code> cluster-wide, that is, providing defaults for every namespace. I'm aware of at least <a href="https://github.com/kubernetes/kubernetes/issues/17097" rel="nofollow noreferrer">one discussion</a> to potentially change this.</p>
