Control Plane and Node Components

Control Plane and Node were formerly referred to as Master/Worker Nodes. You can think of the Control Plane as a node that easily manages other nodes.

Control Plane consists of:

• Api Server: It receives user commands, stores state, and communicates with nodes, performing necessary actions.
• etcd: It is a data store that stores all data related to the Kubernetes cluster and containers, with excellent availability in a distributed system.
• Scheduler: It selects the appropriate node for container creation.
• Controller Manager: It manages various controllers in Kubernetes and informs the API server of its responsibilities.
• Cloud Controller Manager: It integrates various cloud service APIs with Kubernetes.

Node consists of:

• kubelet: Executes, montors and terminates container in conjunction with the Api Server
• kube-proxy: Manages the network of containers

api server: 사용자의 명령을 받아서 상태를 저장하고,Node와 통신하며 필요한 동작들을 수행 etcd: 쿠버네티스 클러스터 및 컨테이너와 관련된 모든 데이터를 저장하는 데이터 저장소, 분산시스템상에서 가용성이 굉장히 좋음 Scheduler: 컨테이너가 생성될 때 적합한 노드를 선택해주는 역할을 수행 Controller Manager: 쿠버네티스의 다양한 컨트롤러들ㅇ르 관리하며 API server가 해야할 일을 알려주는 역할 Cloud controller manager: 클라우드 서비스의 다양한 API를 쿠버네티스와 통합해주는 역할

Example: Container creation

Creating a container can be executed in the following steps:

1. The spec of the container is sent to the Api server.
2. The spec and configuration is stored in etcd
3. The Scheduler determines which node should create the container.
4. The kubelet then receives request from the Api server and creates the container.
5. The status of the container is monitored by kubelet, and is stored in the etcd.