Pod控制器之hpa

简述

HPA全称HorizontalPodAutoscaler Pod水平自动扩缩容，Kubernetes控制器HPA是一种用于自动调整Pod数量的控制器。它可以根据资源使用情况自动增加或减少Pod的数量，以确保应用程序的高可用性和性能。HPA可以根据CPU使用率或自定义指标来进行调整，例如请求延迟或网络吞吐量

Pod 水平自动扩缩中文文档

工作原理

HPA一般通过指示工作负载资源如Deployment、StatefulSet 或其他类似资源进行扩缩容，对于像DaemonSet这种无法扩缩的对象不适用

使用之前我们先安装metrics-server，它可以用来收集集群中的资源使用情况。hpa通过metrics-server的api获取这些数据，然后进行扩缩容的副本计算，得到目标副本数量，如果与当前副本数不相同就通过副本控制器进行scale操作

metrics-server的yaml清单获取
metrics-server

安装完后使用top命令查看

[root@master hpa]# kubectl top node
NAME     CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%   
master   124m         6%     2508Mi          69%       
node01   59m          2%     1941Mi          54%       
node02   53m          2%     2010Mi          55%

hpa资源文件清单

apiVersion: autoscaling/v2beta1  # 使用autoscaling/v2beta1版本的HPA API
kind: HorizontalPodAutoscaler   # 定义HPA控制器
metadata:name: example-hpa   # HPA资源的名称namespace: default  # HPA资源所在的命名空间
spec:scaleTargetRef:apiVersion: apps/v1kind: Deployment   # 所有Pod数量将根据该Deployment对象的副本数量进行自动缩放name: example-deployment  # HPA将控制的Deployment对象名称minReplicas: 2   # 最小Pod数量maxReplicas: 10  # 最大Pod数量metrics:- type: Resource   # 使用资源指标类型resource:name: cpu   # 使用CPU使用率作为资源指标target:type: Utilization   # 使用CPU利用率作为度量标准averageUtilization: 50   # 目标CPU利用率，达到该利用率时触发自动扩缩容- type: Object   # 使用对象指标类型object:metricName: example_http_requests_total   # 自定义指标名称target:type: Value   # 目标值类型，可以是Value或AverageValuevalue: "100"  # 触发自动扩缩容的目标值describedObject:apiVersion: v1kind: Service   # 该对象指标作用于Service对象name: example-service   # 该对象指标作用于的Service对象名称

上面的自定义指标配置不会再本章讲解

案例

下面以一个案例来解释hpa的使用

使用hpa来控制deployment自动扩缩容，当pod资源平均使用率达到3%时进行扩容

创建一个Deployment

apiVersion: apps/v1
kind: Deployment
metadata:name: nginx
spec:selector:matchLabels:app: nginx-hpatemplate:metadata:labels:app: nginx-hpaspec:containers:- name: nginximage: nginx:1.17.1ports:- containerPort: 80protocol: TCPresources:requests:memory: "50Mi"cpu: "100m"

# 创建deployment
[root@master hpa]# kubectl create -f hpa-deploy.yaml 
deployment.apps/nginx created
# 记录下IP后面压测用到 10.244.2.104
[root@master hpa]# kubectl get pod -o wide
NAME                     READY   STATUS    RESTARTS   AGE    IP             NODE     NOMINATED NODE   READINESS GATES
nginx-659b6d57bd-5tbg2   1/1     Running   0          10s   10.244.2.104   node02   <none>           <none>

创建HPA
最小副本数1，最大10 autoscaling/v1版本

apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:name: hpa
spec:minReplicas: 1maxReplicas: 10targetCPUUtilizationPercentage: 3scaleTargetRef:apiVersion: apps/v1kind: Deploymentname: nginx

autoscaling/v2版本

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:name: hpa
spec:minReplicas: 1maxReplicas: 10scaleTargetRef:apiVersion: apps/v1kind: Deploymentname: nginxmetrics:- type: Resourceresource:name: cputarget:type: UtilizationaverageUtilization: 3

# 创建hpa
[root@master hpa]# kubectl create -f hpa.yaml 
horizontalpodautoscaler.autoscaling/hpa created# 查看hpa，还没有完全启动完
[root@master hpa]# kubectl get hpa
NAME   REFERENCE          TARGETS        MINPODS   MAXPODS   REPLICAS   AGE
hpa    Deployment/nginx   <unknown>/3%   1         10        0          6s# 再次查看hpa，启动完成 目前资源使用率 0%
[root@master hpa]# kubectl get hpa
NAME   REFERENCE          TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
hpa    Deployment/nginx   0%/3%     1         10        1          20s

使用ab工具进行压测，没有该工具需要安装 httpd-tools

# 安装 httpd-tools
yum -y install httpd-tools# ab工具可以模拟多个用户（并发请求），向Web服务器发送请求，并统计响应时间和处理请求数量等信息
# ab -n requests -c concurrency url
# 参数说明：
#- requests：总请求数，例如：-n 1000。
#- concurrency：并发请求数，例如：-c 10。
#- url：测试的URL地址。

压测

ab -n 10000 -c 1000 http://10.244.2.104/

观察压测结果

# 监听hpa 发现压测中cpu达到60% ，后面又降回去了
[root@master ~]# kubectl get hpa -w
NAME   REFERENCE          TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
hpa    Deployment/nginx   0%/3%     1         10        1          7m30s
hpa    Deployment/nginx   60%/3%    1         10        1          9m1s
hpa    Deployment/nginx   0%/3%     1         10        4          9m16s
hpa    Deployment/nginx   0%/3%     1         10        8          9m31s
hpa    Deployment/nginx   0%/3%     1         10        10         9m46s

# 监听Pod 一开始只有一个nginx-659b6d57bd-5tbg2 运行了8m47s，压测后又创建了9个Pod，观察ContainerCreating数量
[root@master hpa]# kubectl get pod -w
NAME                     READY   STATUS    RESTARTS   AGE
nginx-659b6d57bd-5tbg2   1/1     Running   0          8m47s
nginx-659b6d57bd-47f98   0/1     Pending   0          0s
nginx-659b6d57bd-47f98   0/1     Pending   0          0s
nginx-659b6d57bd-qs4tr   0/1     Pending   0          0s
nginx-659b6d57bd-tvnmp   0/1     Pending   0          0s
nginx-659b6d57bd-tvnmp   0/1     Pending   0          0s
nginx-659b6d57bd-qs4tr   0/1     Pending   0          0s
nginx-659b6d57bd-47f98   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-qs4tr   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-tvnmp   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-47f98   1/1     Running             0          1s
nginx-659b6d57bd-tvnmp   1/1     Running             0          1s
nginx-659b6d57bd-qs4tr   1/1     Running             0          2s
nginx-659b6d57bd-mccdl   0/1     Pending             0          0s
nginx-659b6d57bd-mccdl   0/1     Pending             0          0s
nginx-659b6d57bd-w9r46   0/1     Pending             0          0s
nginx-659b6d57bd-498c2   0/1     Pending             0          0s
nginx-659b6d57bd-w9r46   0/1     Pending             0          0s
nginx-659b6d57bd-498c2   0/1     Pending             0          0s
nginx-659b6d57bd-mccdl   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-nvhgh   0/1     Pending             0          0s
nginx-659b6d57bd-nvhgh   0/1     Pending             0          0s
nginx-659b6d57bd-w9r46   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-498c2   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-nvhgh   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-mccdl   1/1     Running             0          1s
nginx-659b6d57bd-498c2   1/1     Running             0          1s
nginx-659b6d57bd-w9r46   1/1     Running             0          1s
nginx-659b6d57bd-nvhgh   1/1     Running             0          1s
nginx-659b6d57bd-gq6dc   0/1     Pending             0          0s
nginx-659b6d57bd-gq6dc   0/1     Pending             0          0s
nginx-659b6d57bd-k7vdz   0/1     Pending             0          0s
nginx-659b6d57bd-k7vdz   0/1     Pending             0          0s
nginx-659b6d57bd-gq6dc   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-k7vdz   0/1     ContainerCreating   0          0s
nginx-659b6d57bd-gq6dc   1/1     Running             0          1s
nginx-659b6d57bd-k7vdz   1/1     Running             0          1s

# 观察deploy，看到副本数量也是达到10个
[root@master ~]# kubectl get deploy -w
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
nginx   1/1     1            1           9m19s
nginx   1/4     1            1           10m
nginx   1/4     1            1           10m
nginx   1/4     1            1           10m
nginx   1/4     4            1           10m
nginx   2/4     4            2           10m
nginx   3/4     4            3           10m
nginx   4/4     4            4           10m
nginx   4/8     4            4           10m
nginx   4/8     4            4           10m
nginx   4/8     4            4           10m
nginx   4/8     8            4           10m
nginx   5/8     8            5           10m
nginx   6/8     8            6           10m
nginx   7/8     8            7           10m
nginx   8/8     8            8           10m
nginx   8/10    8            8           11m
nginx   8/10    8            8           11m
nginx   8/10    8            8           11m
nginx   8/10    10           8           11m
nginx   9/10    10           9           11m
nginx   10/10   10           10          11m

压测完后缩容
大概等待五分钟，会看到缩容效果

# deploy的pod副本书已经缩为1个
[root@master ~]# kubectl get deploy -w
nginx   10/10   10           10          11m
nginx   10/1    10           10          16m
nginx   10/1    10           10          16m
nginx   1/1     1            1           16m# 观察Pod，开始逐步缩容 Pod停止Terminating
[root@master ~]# kubectl get pod -w
nginx-659b6d57bd-mccdl   1/1     Terminating         0          5m45s
nginx-659b6d57bd-47f98   1/1     Terminating         0          6m
nginx-659b6d57bd-w9r46   1/1     Terminating         0          5m45s
nginx-659b6d57bd-gq6dc   1/1     Terminating         0          5m30s
nginx-659b6d57bd-nvhgh   1/1     Terminating         0          5m45s
nginx-659b6d57bd-k7vdz   1/1     Terminating         0          5m30s
nginx-659b6d57bd-498c2   1/1     Terminating         0          5m45s
nginx-659b6d57bd-qs4tr   1/1     Terminating         0          6m
nginx-659b6d57bd-tvnmp   1/1     Terminating         0          6m
nginx-659b6d57bd-498c2   0/1     Terminating         0          5m46s
nginx-659b6d57bd-498c2   0/1     Terminating         0          5m46s
nginx-659b6d57bd-498c2   0/1     Terminating         0          5m46s
nginx-659b6d57bd-k7vdz   0/1     Terminating         0          5m31s
nginx-659b6d57bd-k7vdz   0/1     Terminating         0          5m31s
nginx-659b6d57bd-k7vdz   0/1     Terminating         0          5m31s
nginx-659b6d57bd-nvhgh   0/1     Terminating         0          5m46s
nginx-659b6d57bd-nvhgh   0/1     Terminating         0          5m46s
nginx-659b6d57bd-nvhgh   0/1     Terminating         0          5m46s
nginx-659b6d57bd-47f98   0/1     Terminating         0          6m1s
nginx-659b6d57bd-47f98   0/1     Terminating         0          6m2s
nginx-659b6d57bd-47f98   0/1     Terminating         0          6m2s
nginx-659b6d57bd-gq6dc   0/1     Terminating         0          5m32s
nginx-659b6d57bd-gq6dc   0/1     Terminating         0          5m32s
nginx-659b6d57bd-gq6dc   0/1     Terminating         0          5m32s
nginx-659b6d57bd-mccdl   0/1     Terminating         0          5m47s
nginx-659b6d57bd-mccdl   0/1     Terminating         0          5m47s
nginx-659b6d57bd-mccdl   0/1     Terminating         0          5m47s
nginx-659b6d57bd-qs4tr   0/1     Terminating         0          6m2s
nginx-659b6d57bd-w9r46   0/1     Terminating         0          5m47s
nginx-659b6d57bd-qs4tr   0/1     Terminating         0          6m2s
nginx-659b6d57bd-qs4tr   0/1     Terminating         0          6m2s
nginx-659b6d57bd-w9r46   0/1     Terminating         0          5m47s
nginx-659b6d57bd-w9r46   0/1     Terminating         0          5m47s
nginx-659b6d57bd-tvnmp   0/1     Terminating         0          6m3s
nginx-659b6d57bd-tvnmp   0/1     Terminating         0          6m3s
nginx-659b6d57bd-tvnmp   0/1     Terminating         0          6m3s# 只有一个Pod
[root@master ~]# kubectl get pod
NAME                     READY   STATUS    RESTARTS   AGE
nginx-659b6d57bd-5tbg2   1/1     Running   0          18m

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