Horizontal Pod Autoscaling水平Pod自动缩放

Horizontal Pod Autoscaling水平Pod自动缩放

在Kubernetes中，Horizontal Pod Autoscaler自动更新工作负载资源，目的是自动扩展/缩放工作负载以满足需求。

水平扩展意味着对增加负载的响应是部署更多的Pods。这不同于垂直扩展，对于Kubernetes来说，垂直扩展意味着将更多的资源(例如：内存或CPU)分配给已经在为工作负载运行的Pods。

如果负载减少，并且pods的数量高于配置的最小值，Horizontal Pod Autoscaler会指示工作负载资源(部署、StatefulSet或其他类似资源)缩减。

Horizontal Pod Autoscaler自动缩放不适用于无法缩放的对象(例如:DaemonSet。)

运行一个nginx Web服务

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  namespace: openeuler
  labels:
    app: web1
  name: web1
spec:
  replicas: 1
  selector:
    matchLabels:
      app: web1
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: web1
    spec:
      terminationGracePeriodSeconds: 0
      containers:
      - image: nginx
        name: nginx
        imagePullPolicy: IfNotPresent
        resources:
          requests:
            cpu: 150m
status: {}

创建deployment

kubectl apply -f web1.yaml

创建Service

kubectl expose deployment -n openeuler web1  --port 8080 --target-port 80 --type NodePort

创建Horizontal Pod Autoscaler

HPA控制器将增加和减少副本的数量(通过更新部署)，以保持所有Pods的平均CPU利用率为50%。然后部署更新ReplicaSet——这是Kubernetes中所有部署工作的一部分，然后ReplicaSet根据对其.spec的更改添加或删除pod。

创建HorizontalPodAutoscaler

kubectl autoscale deployment -n openeuler web1  --max=5 --cpu-percent 50 -n openeuler

检查hpa

kubectl get hpa -n openeuler 
NAME   REFERENCE         TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
web1   Deployment/web1   0%/50%    1         5         1          28h

增加负载

在一台主机上安装httpd-tools，使用命令ab请求，增加负载

yum -y install httpd-tools

增加负载测试

ab -t 600 -n 1000000 -c 100 http://192.168.26.129:30552/

观察hpa变化

kubectl get hpa -n openeuler  -w
NAME   REFERENCE         TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
web1   Deployment/web1   0%/50%    1         5         1          28h

web1   Deployment/web1   12%/50%   1         5         1          28h
web1   Deployment/web1   280%/50%   1         5         1          28h
web1   Deployment/web1   280%/50%   1         5         4          28h
web1   Deployment/web1   280%/50%   1         5         5          28h
web1   Deployment/web1   159%/50%   1         5         5          28h
web1   Deployment/web1   59%/50%    1         5         5          28h
web1   Deployment/web1   57%/50%    1         5         5          28h
web1   Deployment/web1   58%/50%    1         5         5          28h
web1   Deployment/web1   57%/50%    1         5         5          28h
web1   Deployment/web1   53%/50%    1         5         5          28h
web1   Deployment/web1   54%/50%    1         5         5          28h
web1   Deployment/web1   50%/50%    1         5         5          28h
web1   Deployment/web1   53%/50%    1         5         5          28h
web1   Deployment/web1   58%/50%    1         5         5          28h
web1   Deployment/web1   56%/50%    1         5         5          28h
web1   Deployment/web1   57%/50%    1         5         5          28h
web1   Deployment/web1   53%/50%    1         5         5          28h
web1   Deployment/web1   58%/50%    1         5         5          28h
web1   Deployment/web1   44%/50%    1         5         5          28h
web1   Deployment/web1   54%/50%    1         5         5          28h
web1   Deployment/web1   59%/50%    1         5         5          28h
web1   Deployment/web1   49%/50%    1         5         5          28h
web1   Deployment/web1   54%/50%    1         5         5          28h
web1   Deployment/web1   58%/50%    1         5         5          28h
web1   Deployment/web1   30%/50%    1         5         5          28h
web1   Deployment/web1   0%/50%     1         5         5          28h
web1   Deployment/web1   0%/50%     1         5         5          28h

Pods增加

kubectl get pods -n openeuler 
NAME                    READY   STATUS    RESTARTS      AGE
web1-6d5bd5bdbf-2k5dv   1/1     Running   0             48s
web1-6d5bd5bdbf-4nq8q   1/1     Running   0             48s
web1-6d5bd5bdbf-bdlxl   1/1     Running   0             48s
web1-6d5bd5bdbf-gh6gq   1/1     Running   0             33s
web1-6d5bd5bdbf-xbxl6   1/1     Running   1 (25m ago)   5h2m

通过测试，hpa负载逐步增加，Pod数量增加到5个，测试结束后，hpa负载逐步减少，最后pods数量减少到1个Pod。