If you have Kubernetes workloads that configure Resource Requests on Pods or Containers there’s a footgun “hidden” in a sentence in the documentation (kudos if you spot it immediately):
[…] The kubelet also reserves at least the request amount of that system resource specifically for that container to use. […]
This means Resource Requests actually reserve the requested amount of resources exclusively. To emphasize: this is not a fairness measure in case of over-provisioning! So, if there are Resource Requests you can’t “overprovision” your node/cluster … hell, the new pod won’t even be scheduled although your node is sitting idle. 😵😓
By the time you find out why and have patched the offending resources you’ll be swearing up and down. 🤬
Oh … and wait till you see what the Internat has to say about Resource Limits. 😰