kubernetes之Pod水平自動伸縮(HPA)

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

Horizontal Pod Autoscaling可以根據CPU利用率自動伸縮一個Replication Controller、Deployment 或者Replica Set中的Pod數量。

Horizontal Pod Autoscaler需要使用 Heapster所收集到的 度量數據，請確保Heapster被正確部署到Kubernetes集群中。

使用nginx測試

1）創建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

創建一個HPA控制器，用於監控對象資源利用率

kubectl autoscale deployment nginx-deployment --min=2 --max=6 --cpu-percent=50
# 對nginx的deployment的對象創建HPA控制器，當CPU的使率超過50%時實現自動化擴容，支持1到6之前Pod副本數量，以使得Pod CPU使用率維持在50% 以內。

增加負載

$ 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

檢查pod的負載情況

[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

同時看到replicas已經增加到了5，測試完成。

注意 自動伸縮完成副本數量的改變可能需要幾分鍾的時間。