kube-apiserver
also: API server, Kubernetes API server
The primary control-plane component of Kubernetes that exposes the Kubernetes API and processes all REST requests, serving as the central hub for cluster communication and state management.
kube-apiserver is the main API server in a Kubernetes cluster's control plane. It validates and processes all API requests from users, clients, and internal components, maintaining the cluster's desired state in etcd (the backing datastore).
Every interaction with Kubernetes goes through the API server—whether you're deploying a pod with kubectl apply -f deployment.yaml, scaling a service, or querying cluster status. The server authenticates requests, applies authorization policies, validates manifests, and stores the results.
Example: When you run kubectl get pods, your request reaches kube-apiserver, which authenticates you, checks your permissions, queries etcd for pod objects, and returns the list. Other control-plane components like the scheduler and controller manager also watch the API server for changes to implement their logic.