[Kubernetes] Object 그려보며 이해하기

◎쿠버네티스 Object의 계층 구조

1. Cluster

 - 클러스터 전체에 걸쳐 적용되는 오브젝트.

 - 특정 namespace에 종속되지 않음.

• Namespace: 클러스터 내에서 리소스를 논리적으로 분리하는 단위

# namespace 생성 yaml

apiVersion: v1
kind: Namespace
metadata:
  name: anotherclass-123
  labels:
    part-of: k8s-anotherclass
    managed-by: dashboard

• PersistentVolume(PV): 관리자가 프로비저닝하거나 스토리지 클래스를 통해 동적으로 프로비저닝된 클러스터의 스토리지

2. namespace

 - 특정 namespace 내에서만 유효한 오브젝트

 

• Deployment: Pod를 선언적으로 관리하기 위한 오브젝트

# Deployment 생성 yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  namespace: anotherclass-123
  name: api-tester-1231
  labels:
    part-of: k8s-anotherclass
    component: backend-server
    name: api-tester
    instance: api-tester-1231
    version: 1.0.0
    managed-by: dashboard
spec:
  selector:
    matchLabels:
      part-of: k8s-anotherclass
      component: backend-server
      name: api-tester
      instance: api-tester-1231
  replicas: 2 //pod 생성 갯수
  strategy:	//업데이트 방식
    type: RollingUpdate
  template: //pod 생성 시 적용될 템플릿
    metadata:
      labels:
        part-of: k8s-anotherclass
        component: backend-server
        name: api-tester
        instance: api-tester-1231
        version: 1.0.0
    spec:
      nodeSelector:
        kubernetes.io/hostname: k8s-master
      containers:
        - name: api-tester-1231
          image: 1pro/api-tester:v1.0.0
          ports:
          - name: http
            containerPort: 8080
          envFrom:  //configMap과 연결. 환경변수 값을 제공
            - configMapRef:
                name: api-tester-1231-properties
          startupProbe:  //기동체크 후 실패 시 재기동
            httpGet:
              path: "/startup"
              port: 8080
            periodSeconds: 5
            failureThreshold: 36
          readinessProbe:  // 트래픽 연결 결정
            httpGet:
              path: "/readiness"
              port: 8080
            periodSeconds: 10
            failureThreshold: 3
          livenessProbe:  //서비스 관리. 정상이 아니라면 재시작.
            httpGet:
              path: "/liveness"
              port: 8080
            periodSeconds: 10
            failureThreshold: 3
          resources:  //pod의 cpu, memory 할당 설정. limit을 설정해야 누수를 막을 수 있음.
            requests:
              memory: "100Mi"
              cpu: "100m"
            limits:
              memory: "200Mi"
              cpu: "200m"
          volumeMounts: 
            - name: files  //PVC와 name 매칭되어 연결
              mountPath: /usr/src/myapp/files/dev  //pod 내부에 만들어지는 디렉토리
            - name: secret-datasource
              mountPath: /usr/src/myapp/datasource
      volumes:
        - name: files
          persistentVolumeClaim:
            claimName: api-tester-1231-files
        - name: secret-datasource
          secret:
            secretName: api-tester-1231-postgresql

• Service: Pod 집합에 대한 네트워크 액세스 정책을 정의

# Service

apiVersion: apps/v1
apiVersion: v1
kind: Service
metadata:
  namespace: anotherclass-123
  name: api-tester-1231
  labels:
    part-of: k8s-anotherclass
    component: backend-server
    name: api-tester
    instance: api-tester-1231
    version: 1.0.0
    managed-by: dashboard
spec:
  selector:
    part-of: k8s-anotherclass
    component: backend-server
    name: api-tester
    instance: api-tester-1231
  ports:
    - port: 80
      targetPort: http
      nodePort: 31231
  type: NodePort

• ConfigMap/Secret: 설정 정보와 민감한 정보를 관리

# configMap

apiVersion: v1
kind: ConfigMap
metadata:
  namespace: anotherclass-123
  name: api-tester-1231-properties
  labels:
    part-of: k8s-anotherclass
    component: backend-server
    name: api-tester
    instance: api-tester-1231
    version: 1.0.0
    managed-by: dashboard
data:
  spring_profiles_active: "dev"
  application_role: "ALL"
  postgresql_filepath: "/usr/src/myapp/datasource/postgresql-info.yaml"
---
apiVersion: v1
kind: Secret
metadata:
  namespace: anotherclass-123
  name: api-tester-1231-postgresql
  labels:
    part-of: k8s-anotherclass
    component: backend-server
    name: api-tester
    instance: api-tester-1231
    version: 1.0.0
    managed-by: dashboard
stringData:
  postgresql-info.yaml: |
    driver-class-name: "org.postgresql.Driver"
    url: "jdbc:postgresql://postgresql:5431"
    username: "dev"
    password: "dev123"

• PersistentVolumeClaim(PVC): 사용자가 PV에 대한 요청을 정의

# PVC, PV

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  namespace: anotherclass-123
  name: api-tester-1231-files
  labels:
    part-of: k8s-anotherclass
    component: backend-server
    name: api-tester
    instance: api-tester-1231
    version: 1.0.0
    managed-by: kubectl
spec:
  resources:
    requests:
      storage: 2G
  accessModes:
    - ReadWriteMany
  selector:
    matchLabels:
      part-of: k8s-anotherclass
      component: backend-server
      name: api-tester
      instance: api-tester-1231-files
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: api-tester-1231-files
  labels:
    part-of: k8s-anotherclass
    component: backend-server
    name: api-tester
    instance: api-tester-1231-files
    version: 1.0.0
    managed-by: dashboard
spec:
  capacity:
    storage: 2G
  volumeMode: Filesystem
  accessModes:
    - ReadWriteMany
  local:
    path: "/root/k8s-local-volume/1231"
  nodeAffinity:
    required:
      nodeSelectorTerms:
        - matchExpressions:
            - {key: kubernetes.io/hostname, operator: In, values: [k8s-master]}

• HorizontalPodAutoscaler(HPA): 부하에 따라 Pod 수를 자동으로 조정

 

 

# HPA

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  namespace: anotherclass-123
  name: api-tester-1231-default
  labels:
    part-of: k8s-anotherclass
    component: backend-server
    name: api-tester
    instance: api-tester-1231
    version: 1.0.0
    managed-by: dashboard
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: api-tester-1231
  minReplicas: 2
  maxReplicas: 4
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 60
  behavior:
    scaleUp:
      stabilizationWindowSeconds: 120

 

 

출처 : https://www.inflearn.com/course/%EC%BF%A0%EB%B2%84%EB%84%A4%ED%8B%B0%EC%8A%A4-%EC%96%B4%EB%82%98%EB%8D%94-%ED%81%B4%EB%9E%98%EC%8A%A4-%EC%A7%80%EC%83%81%ED%8E%B8-sprint1