When you set a memory limit on a pod, the limit is passed through the --memory flag on the docker run command. https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/#how-pods-with-resource-limits-are-run
Does Couchbase Server take this into account? Experimentally, it appears to be a no - pod is killed when it overruns. Are you using limits with the Operator?
top shows the full memory of the underlying VM, which AKS doesn’t even let us fully utilize and it is much higher than what we’re trying to set as our limit.