资源的自动申缩，有了资源的使用指标数据后，根据设定的指标比如当cpu使用率达到50%就开始自动扩展

创建一个hpa资源（针对核心资源的监控）

  1. #使用命令的方式创建
  2. kubectl  autoscale deploy nginx-hpa --min=1 --max=8 --cpu-percent=50
  3. #使用资源清单格式创建（yaml的文件）
  4. cat nginx-autoscale-hpa.yaml
  5. apiVersion: autoscaling/v1
  6. kind: HorizontalPodAutoscaler
  7. metadata:
  8.   name: nginx-hpa
  9. spec:
  10.   maxReplicas: 8
  11.   minReplicas: 1
  12.   scaleTargetRef:
  13.     apiVersion: extensions/v1beta1
  14.     kind: Deployment
  15.     name: nginx-hpa
  16.   targetCPUUtilizationPercentage: 50

创建一个deploy和svc资源

cat nginx-hpa.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
    name: nginx-hpa
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx-hpa
      release: canary
  template:
    metadata:
      labels:
        app: nginx-hpa
        release: canary
    spec:
      containers:
      - name: nginx-hpa
        image: ikubernetes/myapp:v3
        ports:
        - name: http
          containerPort: 80
        resources:
          limits:
            cpu: 50m
            memory: 256Mi
          requests: 
            cpu: 50m
            memory: 256Mi
---
apiVersion: v1
kind: Service
metadata:
   name: nginx-hpa-svc
   namespace: default
spec:
  selector:
    app: nginx-hpa
    release: canary
  type: NodePort
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP

对上述svc做ab压测

yum install http-tools -y
ab -c 50 -n 50000 http://10.111.229.8/index.html
32329此端口为svc映射物理机的端口

创建一个针对cpu和内存监控的hpa

cat nginx-autoscale-hpa-v2.yaml
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
  name: nginx-hpa-v2
spec:
  maxReplicas: 8
  minReplicas: 1
  scaleTargetRef:
    apiVersion: extensions/v1beta1
    kind: Deployment
    name: nginx-hpa
  metrics:
  - type: Resource
    resource:
      name: cpu
      targetAverageUtilization: 55
  - type: Resource
    resource:
      name: memory
      targetAverageValue: 50Mi