preoomkiller-controller monitors memory usage metrics for all pods matching
label selector preoomkiller-enabled=true, and when memory usage for pods
go above a threshold, specified in pod annotation preoomkiller.alpha.k8s.zapier.com/memory-threshold, it attempts to evict the pods. This is a very safe operation as
eviction takes into account PodDisruptionBudget and allows for a graceful
termination of the pods.