环境信息
本文的实验环境是k3s
ENV:

#[root@k8s-1 ~]# kubectl get nodes -o wide 

确保metrics-server运行正常

hpa配置

apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
  name: pod-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: hpa
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      targetAverageUtilization: 85
  - type: Resource
    resource:
      name: memory
      targetAverageUtilization: 85

scaleTargetRef 中的三个参数 要注意：
apiVersion，kind，name 均要和pod的描述保持一致

#2.deployment configuration list：
运行pod

kubectl run hpa --image=ikubernetes/myapp:v1 --replicas=1 --requests='cpu=50m,memory=128Mi' --labels=app=myapp'' --expose --port=80

pod 一定要指定cpu，memory ，这样 hpa 中定义的cpu memory两个参数才能获取到信息
结果：
[root@k8s-1 ~]# kubectl get pod,deploy,svc -o wide

压力测试：

安装httpd-tools

yum -y install httpd-tools

压力测试

[root@k8s-1 ~]# ab -c 1000 -n 500000 http://10.43.107.105/index.html

This is ApacheBench, Version 2.3 <$Revision: 1430300 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 10.43.107.105 (be patient)
Completed 50000 requests
Completed 100000 requests
Completed 150000 requests
Completed 200000 requests
Completed 250000 requests
Completed 300000 requests
Completed 350000 requests
Completed 400000 requests
Completed 450000 requests
Completed 500000 requests
Finished 500000 requests


Server Software:        nginx/1.12.2
Server Hostname:        10.43.107.105
Server Port:            80

Document Path:          /index.html
Document Length:        65 bytes

Concurrency Level:      1000
Time taken for tests:   67.163 seconds
Complete requests:      500000
Failed requests:        0
Write errors:           0
Total transferred:      148000000 bytes
HTML transferred:       32500000 bytes
Requests per second:    7444.54 [#/sec] (mean)
Time per request:       134.327 [ms] (mean)
Time per request:       0.134 [ms] (mean, across all concurrent requests)
Transfer rate:          2151.94 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0  105 493.3      5   15082
Processing:     3   29  35.1     13    1626
Waiting:        0   21  28.4      9    1619
Total:          9  134 496.3     18   15170

Percentage of the requests served within a certain time (ms)
  50%     18
  66%     23
  75%     46
  80%    128
  90%    163
  95%   1020
  98%   1042
  99%   3021
 100%  15170 (longest request)

4.测试结果

[root@k8s-1 ~]# kubectl get pods -o wide -w 

NAME                                READY   STATUS        RESTARTS   AGE    IP           NODE       NOMINATED NODE   READINESS GATES
nginx-deployment-59c9f8dff-pk5nr    1/1     Terminating   0          87d    10.42.0.13   myserver   <none>           <none>
nginx-deployment-697cbb4d8b-lpj9w   1/1     Running       0          125m   10.42.0.15   myserver   <none>           <none>
hpa-5d8bcd9f94-6pvrl                1/1     Running       0          119m   10.42.0.16   myserver   <none>           <none>
hpa-5d8bcd9f94-ljbzj                1/1     Running       0          62s    10.42.0.26   myserver   <none>           <none>
hpa-5d8bcd9f94-4dhfs                1/1     Running       0          62s    10.42.0.27   myserver   <none>           <none>
hpa-5d8bcd9f94-q4gfc                1/1     Running       0          62s    10.42.0.25   myserver   <none>           <none>
hpa-5d8bcd9f94-b6rp9                1/1     Running       0          47s    10.42.0.31   myserver   <none>           <none>
hpa-5d8bcd9f94-bcbb8                1/1     Running       0          47s    10.42.0.29   myserver   <none>           <none>
hpa-5d8bcd9f94-2gws5                1/1     Running       0          47s    10.42.0.30   myserver   <none>           <none>
hpa-5d8bcd9f94-crpdc                1/1     Running       0          47s    10.42.0.28   myserver   <none>           <none>
hpa-5d8bcd9f94-zrjc8                1/1     Running       0          32s    10.42.0.32   myserver   <none>           <none>

出现了9个扩展的pod

查看hpa的状态

kubectl get  hpa

NAME      REFERENCE        TARGETS          MINPODS   MAXPODS   REPLICAS   AGE
pod-hpa   Deployment/hpa   1%/85%, 0%/85%   1         10        9          119m

[root@myserver ~]# kubectl  describe hpa/pod-hpa
Name:                                                     pod-hpa
Namespace:                                                default
Labels:                                                   <none>
Annotations:                                              kubectl.kubernetes.io/last-applied-configuration:
                                                            {"apiVersion":"autoscaling/v2beta1","kind":"HorizontalPodAutoscaler","metadata":{"annotations":{},"name":"pod-hpa","namespace":"default"},...
CreationTimestamp:                                        Tue, 10 Mar 2020 11:28:39 +0800
Reference:                                                Deployment/hpa
Metrics:                                                  ( current / target )
  resource memory on pods  (as a percentage of request):  1% (2369763555m) / 85%
  resource cpu on pods  (as a percentage of request):     0% (0) / 85%
Min replicas:                                             1
Max replicas:                                             10
Deployment pods:                                          9 current / 9 desired
Conditions:
  Type            Status  Reason               Message
  ----            ------  ------               -------
  AbleToScale     True    ScaleDownStabilized  recent recommendations were higher than current one, applying the highest recent recommendation
  ScalingActive   True    ValidMetricFound     the HPA was able to successfully calculate a replica count from memory resource utilization (percentage of request)
  ScalingLimited  False   DesiredWithinRange   the desired count is within the acceptable range
Events:
  Type    Reason             Age                   From                       Message
  ----    ------             ----                  ----                       -------
  Normal  SuccessfulRescale  3m41s (x2 over 117m)  horizontal-pod-autoscaler  New size: 4; reason: cpu resource utilization (percentage of request) above target
  Normal  SuccessfulRescale  3m26s (x2 over 117m)  horizontal-pod-autoscaler  New size: 8; reason: cpu resource utilization (percentage of request) above target
  Normal  SuccessfulRescale  3m11s (x2 over 117m)  horizontal-pod-autoscaler  New size: 9; reason: