14-应用的弹性伸缩 HPA

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HPA是kubernetes里面pod弹性伸缩的实现方法,它能根据设置的监控阀值进行pod的弹性缩的，HPA默认只能支持cpu的阀值检测扩缩容，但也可以通过custom metric api 调用prometheus实现自定义metric 来更加灵活的监控指标实现弹性伸缩。但hpa不能用于伸缩一些无法进行缩放的控制器如DaemonSet。

部署Metric-Server

1.1.部署带有资源请求的Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: damon
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.9.0
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80
        resources:
          requests:
            cpu: "100m"

kubectl expose deployment damon

1.2 创建HPA
kubectl autoscale deployment damon —max=10 —min=1 —cpu-percent=80

1.3 增加cpu负载验证pod是否扩容
watch -n1 ‘kubectl top pod && kubectl get hpa && kubectl get pod’
# 安装压力测试工具WebBench
yum -y install gcc
git clone https://github.com/EZLippi/WebBench.git
cd WebBench
make ; make install
# 压力测试,递增的扩容，并不是一次扩容到最大值
webbench -c 1000 -t 60 http://10.43.77.199/
watch -n1 ‘kubectl get hpa && kubectl top pod && kubectl get pod’