# 创建deploy和service
$ kubectl run php-apache --image=pilchard/hpa-example --requests=cpu=200m --expose --port=80

# 创建autoscaler
$ kubectl autoscale deploy php-apache --cpu-percent=50 --min=1 --max=10

# 等待3~5分钟查看hpa状态
$ kubectl get hpa php-apache
NAME         REFERENCE               TARGETS    MINPODS   MAXPODS   REPLICAS   AGE
php-apache   Deployment/php-apache   0% / 50%   1         10        1          3m

# 增加负载
$ kubectl run --rm -it load-generator --image=busybox /bin/sh
Hit enter for command prompt
$ while true; do wget -q -O- http://php-apache; done;

# 等待约5分钟查看hpa显示负载增加，且副本数目增加为4
$ kubectl get hpa php-apache
NAME         REFERENCE               TARGETS      MINPODS   MAXPODS   REPLICAS   AGE
php-apache   Deployment/php-apache   430% / 50%   1         10        4          4m

# 注意k8s为了避免频繁增删pod，对副本的增加速度有限制
# 实验过程可以看到副本数目从1到4到8到10，大概都需要4~5分钟的缓冲期
$ kubectl get hpa php-apache
NAME         REFERENCE               TARGETS     MINPODS   MAXPODS   REPLICAS   AGE
php-apache   Deployment/php-apache   86% / 50%   1         10        8          9m
$ kubectl get hpa php-apache
NAME         REFERENCE               TARGETS     MINPODS   MAXPODS   REPLICAS   AGE
php-apache   Deployment/php-apache   52% / 50%   1         10        10         12m

# 清除负载，CTRL+C 结束上述循环程序，稍后副本数目变回1
$ kubectl get hpa php-apache
NAME         REFERENCE               TARGETS    MINPODS   MAXPODS   REPLICAS   AGE
php-apache   Deployment/php-apache   0% / 50%   1         10        1          17m