Which component in Kubernetes is responsible to watch newly created Pods with no assigned node, and selects a node for them to run on?

The kube-scheduler is a core component of the Kubernetes control plane. Its exclusive function is to monitor for newly created Pods that do not have a nodeName specified. For every such Pod, the scheduler identifies the most suitable Node for it to run on based on configured policies, resource requirements, and constraints. Once a suitable node is found, the scheduler binds the Pod to that node, a process which involves updating the Pod's nodeName field.

A. etcd is a distributed key-value store used as Kubernetes' backing store for all cluster data. It does not perform scheduling.
B. kube-controller-manager runs various controllers, but the specific task of pod-to-node assignment is handled by the dedicated kube-scheduler.
C. kube-proxy is a network proxy that runs on each node, maintaining network rules and enabling communication. It is not involved in scheduling decisions.

1. Kubernetes Documentation. (n.d.). Components of Kubernetes. Kubernetes. Retrieved from https://kubernetes.io/docs/concepts/overview/components/. (See section "kube-scheduler").

2. Kubernetes Documentation. (n.d.). Kubernetes Scheduler. Kubernetes. Retrieved from https://kubernetes.io/docs/concepts/scheduling-eviction/kube-scheduler/. (See section "What the scheduler is").