kubernetes雲平臺管理實戰：HPA水平自動伸縮（十一）

時間 2019-11-07

標籤 kubernetes 平臺管理實戰 hpa 水平自動伸縮十一简体版

原文原文鏈接

1、自動伸縮

一、啓動php

[root@k8s-master ~]# kubectl autoscale deployment nginx-deployment --max=8 --min=2 --cpu-percent=80
deployment "nginx-deployment" autoscaled

二、查看建立node

[root@k8s-master ~]# kubectl get all
NAME                      DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/nginx-deployment   2         2         2            2           13h

NAME                   REFERENCE                     TARGET    CURRENT   MINPODS   MAXPODS   AGE
hpa/nginx-deployment   Deployment/nginx-deployment   80%       0%        2         8         17s

NAME             CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
svc/kubernetes   10.254.0.1      <none>        443/TCP        2d
svc/nginx        10.254.145.15   <nodes>       80:32000/TCP   1d

NAME                             DESIRED   CURRENT   READY     AGE
rs/nginx-deployment-2950479891   0         0         0         13h
rs/nginx-deployment-3113009173   2         2         2         13h

NAME                                   READY     STATUS    RESTARTS   AGE
po/nginx-deployment-3113009173-h5plc   1/1       Running   0          17s
po/nginx-deployment-3113009173-vckhg   1/1       Running   1          13h

三、修改副本數爲1nginx

[root@k8s-master ~]# kubectl edit deployment nginx-deployment
修改成1
replicas: 1
deployment "nginx-deployment" edited
[root@k8s-master ~]# kubectl get all
NAME                      DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/nginx-deployment   1         1         1            1           13h

NAME             CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
svc/kubernetes   10.254.0.1      <none>        443/TCP        2d
svc/nginx        10.254.145.15   <nodes>       80:32000/TCP   1d

NAME                             DESIRED   CURRENT   READY     AGE
rs/nginx-deployment-2950479891   0         0         0         13h
rs/nginx-deployment-3113009173   1         1         1         13h

NAME                                   READY     STATUS    RESTARTS   AGE
po/nginx-deployment-3113009173-vckhg   1/1       Running   1          13h

2、hpa伸縮

一、編輯horizontalpodautoscaler 文件

[root@k8s-master ~]# kubectl get horizontalpodautoscaler 
NAME               REFERENCE                     TARGET    CURRENT   MINPODS   MAXPODS   AGE
nginx-deployment   Deployment/nginx-deployment   80%       0%        2         8         1m

# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
  creationTimestamp: 2019-01-22T01:00:02Z
  name: nginx-deployment
  namespace: default
  resourceVersion: "41194"
  selfLink: /apis/autoscaling/v1/namespaces/default/horizontalpodautoscalers/nginx-deployment
  uid: 0c897472-1de1-11e9-9773-000c292bd9e1
spec:
  maxReplicas: 8
  minReplicas: 2
  scaleTargetRef:
    apiVersion: extensions/v1beta1
    kind: Deployment
    name: nginx-deployment
  targetCPUUtilizationPercentage: 80
status:
  currentCPUUtilizationPercentage: 0
  currentReplicas: 2
  desiredReplicas: 2
  lastScaleTime: 2019-01-22T01:00:02Z

二、修改副本爲1

[root@k8s-master ~]# kubectl edit deployment nginx-deployment
  replicas: 1
deployment "nginx-deployment" edited
[root@k8s-master ~]# kubectl get all
NAME                      DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/nginx-deployment   2         2         2            2           13h

NAME                   REFERENCE                     TARGET    CURRENT   MINPODS   MAXPODS   AGE
hpa/nginx-deployment   Deployment/nginx-deployment   80%       0%        2         8         6m

NAME             CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
svc/kubernetes   10.254.0.1      <none>        443/TCP        2d
svc/nginx        10.254.145.15   <nodes>       80:32000/TCP   1d

NAME                             DESIRED   CURRENT   READY     AGE
rs/nginx-deployment-2950479891   0         0         0         13h
rs/nginx-deployment-3113009173   2         2         2         13h

NAME                                   READY     STATUS    RESTARTS   AGE
po/nginx-deployment-3113009173-9hlq1   1/1       Running   0          2s
po/nginx-deployment-3113009173-vckhg   1/1       Running   1          13h

明明修改成1，怎麼還有2個？是由於hpa以下配置apache

spec:
  maxReplicas: 8
  minReplicas: 2

三、修改副本數爲5

[root@k8s-master ~]# kubectl edit hpa nginx-deployment
修改：
spec:
  maxReplicas: 8
  minReplicas: 5
horizontalpodautoscaler "nginx-deployment" edited
[root@k8s-master ~]# kubectl get all
NAME                      DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/nginx-deployment   5         5         5            2           13h

NAME                   REFERENCE                     TARGET    CURRENT   MINPODS   MAXPODS   AGE
hpa/nginx-deployment   Deployment/nginx-deployment   80%       0%        5         8         8m

NAME             CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
svc/kubernetes   10.254.0.1      <none>        443/TCP        2d
svc/nginx        10.254.145.15   <nodes>       80:32000/TCP   1d

NAME                             DESIRED   CURRENT   READY     AGE
rs/nginx-deployment-2950479891   0         0         0         13h
rs/nginx-deployment-3113009173   5         5         2         13h

NAME                                   READY     STATUS              RESTARTS   AGE
po/nginx-deployment-3113009173-97l9c   0/1       ContainerCreating   0          2s
po/nginx-deployment-3113009173-9hlq1   1/1       Running             0          2m
po/nginx-deployment-3113009173-qq4h8   0/1       ContainerCreating   0          2s
po/nginx-deployment-3113009173-sfp8z   0/1       ContainerCreating   0          2s
po/nginx-deployment-3113009173-vckhg   1/1       Running             1          13h

看到自動伸縮的過程了吧！api

3、HAP-deployment-rs-rc-pod調用原理

一、什麼是hpa緩存

Horizontal Pod Autoscaling能夠根據CPU使用率或應用自定義metrics自動擴展Pod數量（支持replication controller、deployment和replica set）。bash

控制管理器每隔30s（能夠經過–horizontal-pod-autoscaler-sync-period修改）查詢metrics的資源使用狀況
支持三種metrics類型
- 預約義metrics（好比Pod的CPU）以利用率的方式計算
- 自定義的Pod metrics，以原始值（raw value）的方式計算
- 自定義的object metrics
支持兩種metrics查詢方式：Heapster和自定義的REST API
支持多metrics

客戶端;ui

經過kubectl建立一個horizontalPodAutoscaler對象，並存儲到etcd中this

服務端：google

api server:負責接受建立hpa對象，而後存入etcd

hpa controler和其餘的controler相似，每30s同步一次，將已經建立的hpa進行一次管理（從heapster獲取監控數據，查看是否須要scale, controler的store中就保存着從始至終建立出來的hpa，當作一個緩存），watch hpa有變化也會運行。從heapster中獲取scale數據，和hpa對比，計算cup利用率等信息，而後從新調整scale。根據hpa.Spec.ScaleTargetRef.Kind（例如Deployment，而後deployment控制器在調整pod數量），調整其值，發送到apiserver存儲到etcd，而後更新hpa到etcd.

二、示例

# 建立pod和service
$ kubectl run php-apache --image=gcr.io/google_containers/hpa-example --requests=cpu=200m --expose --port=80
service "php-apache" created
deployment "php-apache" created

# 建立autoscaler
$ kubectl autoscale deployment php-apache --cpu-percent=50 --min=1 --max=10
deployment "php-apache" autoscaled
$ kubectl get hpa
NAME         REFERENCE                     TARGET    CURRENT   MINPODS   MAXPODS   AGE
php-apache   Deployment/php-apache/scale   50%       0%        1         10        18s

# 增長負載
$ kubectl run -i --tty load-generator --image=busybox /bin/sh
Hit enter for command prompt
$ while true; do wget -q -O- http://php-apache.default.svc.cluster.local; done

# 過一會就能夠看到負載升高了
$ kubectl get hpa
NAME         REFERENCE                     TARGET    CURRENT   MINPODS   MAXPODS   AGE
php-apache   Deployment/php-apache/scale   50%       305%      1         10        3m

# autoscaler將這個deployment擴展爲7個pod
$ kubectl get deployment php-apache
NAME         DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
php-apache   7         7         7            7           19m

# 刪除剛纔建立的負載增長pod後會發現負載下降，而且pod數量也自動降回1個
$ kubectl get hpa
NAME         REFERENCE                     TARGET    CURRENT   MINPODS   MAXPODS   AGE
php-apache   Deployment/php-apache/scale   50%       0%        1         10        11m

$ kubectl get deployment php-apache
NAME         DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
php-apache   1         1         1            1           27m

三、關係原理圖　

四、小結

一、首先最底層的資源永遠都是pod
二、比pod高級一點的資源叫rc副本控制器
三、在pod上面有一個高級的rs
四、那誰來管理rs呢？是deployment
五、HPA自動管理deployment，deployment設置爲1，HPA最低設置爲3，deployment這就會被自動設計爲3個

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