쿠버네티스 예제를 활용한 애플리케이션 개발 (2)

# 자동 스케일링 기능 구현

- 이전 사용한 리소스 삭제

kubectl delete all --all -n wordpress

kubectl delete pvc -n wordpress wp-pv-claim

kubectl delete pvc -n wordpress mysql-pv-claim

# resource limits 설정하기

쿠버네티스 공식사이트 > resource limits > 리소스 제한 코드 확인

vim wordpress-deployment.yaml

apiVersion: v1
kind: Service
metadata:
  name: wordpress
  namespace: wordpress
  labels:
    app: wordpress
spec:
  ports:
    - port: 80
  selector:
    app: wordpress
    tier: frontend
  type: LoadBalancer
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: wp-pv-claim
  namespace: wordpress
  labels:
    app: wordpress
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi
---
apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: wordpress
  namespace: wordpress
  labels:
    app: wordpress
spec:
  selector:
    matchLabels:
      app: wordpress
      tier: frontend
  template:
    metadata:
      labels:
        app: wordpress
        tier: frontend
    spec:
      nodeSelector:
        app: wordpress
      containers:
      - resources:
          requests:
            memory: "500Mi"
            cpu: "100m"
          limits:
            memory: "1024Mi"
            cpu: "300m"
        image: wordpress:4.8-apache
        name: wordpress
        env:
        - name: WORDPRESS_DB_HOST
          value: wordpress-mysql
        - name: WORDPRESS_DB_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-pass
              key: password
        ports:
        - containerPort: 80
          name: wordpress
        volumeMounts:
        - name: wordpress-persistent-storage
          mountPath: /var/www/html
      volumes:
      - name: wordpress-persistent-storage
        persistentVolumeClaim:
          claimName: wp-pv-claim

vim mysql-deployment.yaml

apiVersion: v1
kind: Service
metadata:
  name: wordpress-mysql
  namespace: wordpress
  labels:
    app: wordpress
spec:
  ports:
    - port: 3306
  selector:
    app: wordpress
    tier: mysql
  clusterIP: None
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim
  namespace: wordpress
  labels:
    app: wordpress
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi
---
apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: wordpress-mysql
  namespace: wordpress
  labels:
    app: wordpress
spec:
  selector:
    matchLabels:
      app: wordpress
      tier: mysql
  template:
    metadata:
      labels:
        app: wordpress
        tier: mysql
    spec:
      nodeSelector:
        app: mysql
      containers:
      - resources:
          requests:
            memory: "256Mi"
            cpu: "50m"
          limits:
            memory: "512Mi"
            cpu: "100m"
        image: mysql:5.6
        name: mysql
        env:
        - name: MYSQL_ROOT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-pass
              key: password
        ports:
        - containerPort: 3306
          name: mysql
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
      volumes:
      - name: mysql-persistent-storage
        persistentVolumeClaim:
          claimName: mysql-pv-claim

# 폴더의 모든 yaml 파일을 실행하기

kubectl apply -k ./

# 확인하기

kubectl get pod -w -n wordpress

# hpa 적용하기

쿠버네티스 공식 사이트 > hpa 검색 > 워크스루

kubectl get pod -w -n wordpress

# 워드 프레스를 감시하는 hpa를 생성

kubectl autoscale deployment wordpress --cpu-percent=50 --min=1 --max=10 -n wordpress

kubectl autoscale deployment wordpress-mysql --cpu-percent=50 --min=1 --max=10 -n wordpress

# 워드 프레스를 감시하는 hpa를 조회

kubectl get hpa -w -n wordpress

- 부하가 증가하거나 트래픽이 많아진다면 replicas를 증가시켜 부하를 분산시킨다.