(Kubernetes) Kubernetes Architecture 2

ETCD
key-value store format database

ETCD role : 
Every information you see when you run the kubectl get command is from the ETCD server
across Master node  multiple ETCD instances

kube-api

Authenticating and validating request, retrieving, updating data in ETCD data store 역할을 한다

kube controller manager
is a precess that continuously monitors the state of various components within the system.

kube scheduler
only decide which pod goes on which node. not move.

kubelet
register the node with the kubernetes cluster.
continuews to monitor the state of the POD and the containers in it and reports to the kube-api server on timely basis.
You must always manually install the kublete on your worker nodes

kube proxy
is a process that runs on each node in the kubernetes cluster.
다른 노드의 POD에 통신할수 있게 함

POD
A pod is the smallest object that you can create in Cuba unless.
Multi-Container PODs 
Single pod can have multiple containers.   

POD with YAML
Kubernetes definition file always contains four top level fields.
The API version kind metadata and spec.

 

apiVersion: v1              # 쿠버네티스 버전
kind: Pod                   # 오브젝트 종류
metadata:
    name: chacha-simple     # pod 이름
spec:
    containers:
    - image: chacha/exp     # 컨테이너 이미지
      name: cha             # 생성될 컨테이너 이름
      ports:
      - containerPort: 8080 # 컨테이너 포트
        protocol: TCP
      
status:
    conditions:
    - status: "True"
      type: Ready
    containerStatuses:
    - containerID: docker://f03234
      image: chacha/exp
      imageID: docker://43cfsc32
      name: cha
      ready: True
      restartCount: 0
      state:
          running: 
                  startedAt: 2020-09-18T12:46:05z
    hostIP: 10.132.0.4
    phase: Running
    podIP: 10.0.2.3
    startTime: 2020-09-18-T12:46:05z