自动扩容之Horizontal Pod Autoscaling(HPA)

先运行几个pods.

代码语言：javascript复制

apiVersion: apps/v1
kind: Deployment
metadata:
  name: dp-tomcat
  namespace: learning
spec:
  revisionHistoryLimit: 15
  replicas: 1
  selector:
    matchLabels:
      app: dp-tomcat
    matchExpressions:
      - key: app
        operator: In
        values: [dp-tomcat]
  template:
    metadata:
      labels:
        app: dp-tomcat
    spec:
      nodeSelector:
        kubernetes.io/hostname: dev-k8s-05.xsl.link
      containers:
      - name: dp-tomcat
        image: tomcat:9.0
        resources:
          limits:
            memory: "1024Mi"
            cpu: "500m"
        ports:
        - containerPort: 8080
          name: web

上面的yaml说明一下:

• 运行了一个副本数为3的deployment
• 暴露出一个名为nginxsvc的service
• 指定了`revisionHistoryLimit`表示保留历史版本的个数
• 因为要通过资源负载模拟HPA功能的场景，必须依赖template中对pod做资源限制
• 集群环境需要安装metrics-server,方便观察集群资源负载

代码语言：javascript复制

➜  00-template.resources.yaml git:(master) ✗ (☸ kubernetes-admin@kubernetes:default) k get pods -n learning        
NAME                               READY   STATUS    RESTARTS   AGE
abcontainer-58c67cfb87-g4j8q       1/1     Running   0          25d
dp-tomcat-5b4465b6bf-82llc         1/1     Running   0          125m
dp-tomcat-5b4465b6bf-zsttg         1/1     Running   0          126m
nginx-deployment-8558b4659-6dkmr   1/1     Running   0          17s
nginx-deployment-8558b4659-v8fzf   1/1     Running   0          17s
nginx-deployment-8558b4659-w5tlq   1/1     Running   0          8m56s

定义一个HPA资源对象

代码语言：javascript复制

apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
  name: dp-tomcat
  namespace: learning
spec:
  minReplicas: 1
  maxReplicas: 10
  scaleTargetRef:
    kind: Deployment
    name: dp-tomcat
    apiVersion: apps/v1
  targetCPUUtilizationPercentage: 10

运行一个客户端程序

代码语言：javascript复制

apiVersion: apps/v1
kind: Deployment
metadata:
  name: abcontainer
  namespace: abcontainer
spec:
  selector:
    matchLabels:
      app: abcontainer
  template:
    metadata:
      labels:
        app: abcontainer
    spec:
      containers:
      - name: abcontainer
        image: httpd
        ports:
        - containerPort: 80

进入到abcontainer通过ab增加负载

代码语言：javascript复制

k exec abcontainer-58c67cfb87-g4j8q -n learning -it -- bash

压力测试

代码语言：javascript复制

ab -c 5000 -n 2000000 http://tomcat-svc:8080/

查看HPA资源变化

代码语言：javascript复制

NAME        REFERENCE              TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
dp-tomcat   Deployment/dp-tomcat   0%/10%    1         10        1          16m
NAME        REFERENCE              TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
dp-tomcat   Deployment/dp-tomcat   98%/10%   1         10        1          18m
# 中断ab测试
NAME        REFERENCE              TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
dp-tomcat   Deployment/dp-tomcat   36%/10%   1         10        10         19m
# pods的变化
NAME                           READY   STATUS              RESTARTS   AGE
abcontainer-58c67cfb87-g4j8q   1/1     Running             0          25d
dp-tomcat-96b7b9f6f-54v84      0/1     Pending             0          13s
dp-tomcat-96b7b9f6f-55hsf      0/1     ContainerCreating   0          13s
dp-tomcat-96b7b9f6f-btbzr      0/1     ContainerCreating   0          13s
dp-tomcat-96b7b9f6f-dpppj      0/1     ContainerCreating   0          13s
dp-tomcat-96b7b9f6f-k4jqq      1/1     Running             0          12m
dp-tomcat-96b7b9f6f-mxd4f      1/1     Running             0          28s
dp-tomcat-96b7b9f6f-tjpj6      1/1     Running             0          28s
dp-tomcat-96b7b9f6f-zztqm      1/1     Running             0          28s

默认情况下,当流量下降，5分钟后pod的数量会慢慢恢复到replicas的值

deployment metrics server service yaml

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