Kubernetes Scheduler: How Pods Get Placed on Nodes#

The scheduler (kube-scheduler) watches for newly created pods that have no node assignment. For each unscheduled pod, the scheduler selects the best node and writes a binding back to the API server. The kubelet on that node then starts the pod. If no node is suitable, the pod stays Pending until conditions change.

The scheduler is the reason pods run where they do. Understanding its internals is essential for diagnosing Pending pods, designing placement constraints, and managing cluster utilization.