Resource defaults and limitations are a good first step towards preventing malicious or accidental deployment of Pods that can potentially produce adverse effects on the cluster. Still, any user with the permissions to create Pods in a Namespace can overload the system. Even if max values are set to some reasonably small amount of memory and CPU, a user could deploy thousands, or even millions of Pods, and “eat” all the available cluster resources. Such an effect might not be even produced out of malice but accidentally.

A Pod might be attached to a system that scales it automatically without defining upper bounds and, before we know it, it might scale to too many replicas. There are also many other ways things might get out of control.