K8s 集群是什么？

Kubernetes 集群是一组用于运行容器化(容器可以是docker, VMWare, VirtualBox等)应用的节点计算机(真机或虚拟机，例如Aliyun的ECS)。 如果您正在运行 Kubernetes，那么您运行的其实就是集群 。

A Kubernetes cluster is a set of node machines for running containerized applications. If you’re running Kubernetes, you’re running a cluster.

集群至少包含一个控制平面，以及一个或多个计算机器或节点。控制平面负责维护集群的预期状态，例如运行哪个应用以及使用哪个容器镜像。节点则负责应用和工作负载的实际运行。(我理解这个就是 master )

At a minimum, a cluster contains a control plane and one or more compute machines, or nodes. The control plane is responsible for maintaining the desired state of the cluster, such as which applications are running and which container images they use. Nodes actually run the applications and workloads.

集群是 Kubernetes 的核心优势：能够在内部或云端跨一组机器（无论是物理机还是虚拟机）调度和运行容器。Kubernetes 容器不受单个计算机的限制。相反，它们是跨整个集群进行抽象。

The cluster is the heart of Kubernetes’ key advantage: the ability to schedule and run containers across a group of machines, be they physical or virtual, on premises or in the cloud. Kubernetes containers aren’t tied to individual machines. Rather, they’re abstracted across the cluster.

参考原文
https://www.redhat.com/en/topics/containers/what-is-a-kubernetes-cluster