kubernetes之Pod水平自动伸缩(HPA)

https://k8smeetup.github.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/

Horizontal Pod Autoscaling可以根据CPU利用率自动伸缩一个Replication Controller、Deployment 或者Replica Set中的Pod数量。

Horizontal Pod Autoscaler需要使用Heapster所收集到的 度量数据，请确保Heapster被正确部署到Kubernetes集群中。

使用nginx测试

1）创建deployment和service

[root@node-01 ~]# cat deployment-nginx.yaml
apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 2 # tells deployment to run 2 pods matching the template
  template: # create pods using pod definition in this template
    metadata:
      labels:
        app: nginx
    spec:
      nodeSelector:
        app: nginx
      containers:
      - name: nginx
        image: nginx:1.8
        ports:
        - containerPort: 80
        livenessProbe:
          httpGet:
            path: /
            port: 80
          initialDelaySeconds: 10
          timeoutSeconds: 2
          periodSeconds: 10
        resources:
          limits:
            cpu: 200m
            memory: 30Mi
          requests:
            cpu: 100m
            memory: 20Mi
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-deployment
  labels:
    app: nginx-deployment
spec:
  ports:
  - port: 80
    protocol: TCP
  selector:
    app: nginx

[root@node-01 ~]# kubectl apply -f deployment-nginx.yaml

创建一个HPA控制器，用于监控对象资源利用率

kubectl autoscale deployment nginx-deployment --min=2 --max=6 --cpu-percent=50
# 对nginx的deployment的对象创建HPA控制器，当CPU的使率超过50%时实现自动化扩容，支持1到6之前Pod副本数量，以使得Pod CPU使用率维持在50% 以内。

增加负载

$ kubectl run -i --tty load-generator --image=busybox /bin/sh
 
Hit enter for command prompt
 
$ while true; do wget -q -O- http://nginx-deployment; done

检查pod的负载情况

[root@node-01 ~]# kubectl get hpa
NAME               REFERENCE                     TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
nginx-deployment   Deployment/nginx-deployment   4%/20%    2         5         2          28h
[root@node-01 ~]# kubectl get hpa
NAME               REFERENCE                     TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
nginx-deployment   Deployment/nginx-deployment   64%/20%   2         5         5          28h

同时看到replicas已经增加到了5，测试完成。

注意 自动伸缩完成副本数量的改变可能需要几分钟的时间。