Horizontal Pod Autoscaling（Pod水平自動(dòng)伸縮），簡(jiǎn)稱HPA。HAP通過監(jiān)控分析RC或者Deployment控制的所有Pod的負(fù)載變化情況來確定是否需要調(diào)整Pod的副本數(shù)量，這是HPA最基本的原理。
HPA在kubernetes集群中被設(shè)計(jì)成一個(gè)controller，HPA Controller默認(rèn)30s輪詢一次（可通過kube-controller-manager的標(biāo)志--horizontal-pod-autoscaler-sync-period進(jìn)行設(shè)置），查詢指定的資源（RC或者Deployment）中Pod的資源使用率，并且與創(chuàng)建時(shí)設(shè)定的值和指標(biāo)做對(duì)比，從而實(shí)現(xiàn)自動(dòng)伸縮的功能。
HPA可以從兩個(gè)地方獲取數(shù)據(jù)：
1、Heapster：僅支持CPU使用率
2、自定義監(jiān)控

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安裝配置heapster
https://github.com/kubernetes-retired/heapster/tree/v1.4.2/deploy/kube-config/influxdb
$ docker pull docker.io/zhaoqing/heapster-amd64:1.4.2
$ docker pull docker.io/pupudaye/heapster-influxdb-amd64:v1.3.3
1、安裝heapster數(shù)據(jù)庫influxdb

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: monitoring-influxdb
  namespace: kube-system
spec:
  replicas: 1
  template:
    metadata:
      labels:
        task: monitoring
        k8s-app: influxdb
    spec:
      containers:
      - name: influxdb
        image: docker.io/pupudaye/heapster-influxdb-amd64:v1.3.3
        volumeMounts:
        - mountPath: /data
          name: influxdb-storage
      volumes:
      - name: influxdb-storage
        emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
  labels:
    task: monitoring
    kubernetes.io/cluster-service: 'true'
    kubernetes.io/name: monitoring-influxdb
  name: monitoring-influxdb
  namespace: kube-system
spec:
  ports:
  - port: 8086
    targetPort: 8086
  selector:
    k8s-app: influxdb

2、安裝heapster

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: heapster
  namespace: kube-system
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: dongyali-sa2-clusterrolebinding
subjects:
- kind: ServiceAccount
  name: heapster
  namespace: kube-system
roleRef:
  kind: ClusterRole
  name: cluster-admin
  apiGroup: rbac.authorization.k8s.io
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: heapster
  namespace: kube-system
spec:
  replicas: 1
  template:
    metadata:
      labels:
        task: monitoring
        k8s-app: heapster
    spec:
      serviceAccountName: heapster
      containers:
      - name: heapster
        image: docker.io/zhaoqing/heapster-amd64:1.4.2
        imagePullPolicy: IfNotPresent
        command:
        - /heapster
        - --source=kubernetes:https://kubernetes.default
        - --sink=influxdb:http://monitoring-influxdb.kube-system.svc:8086
---
apiVersion: v1
kind: Service
metadata:
  labels:
    task: monitoring
    kubernetes.io/cluster-service: 'true'
    kubernetes.io/name: Heapster
  name: heapster
  namespace: kube-system
spec:
  ports:
  - port: 80
    targetPort: 8082
  selector:
    k8s-app: heapster

3、修改kube-controller-manager.yaml
$ cd /etc/kubernetes/manifests/
$ vim kube-controller-manager.yaml

spec:
  containers:
  - command:
    - kube-controller-manager
    - --horizontal-pod-autoscaler-use-rest-clients=false         #增加

修改后自動(dòng)生效
4、創(chuàng)建應(yīng)用pod用戶測(cè)試hpa

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: hpa-nginx-deploy
  labels:
    app: nginx-demo
spec:
  revisionHistoryLimit: 15
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        resources:
          requests:
            cpu: 100m
        ports:
        - containerPort: 80

5、針對(duì)上述pod創(chuàng)建hpa
$ kubectl autoscale deployment hpa-nginx-deploy --cpu-percent=10 --min=1 --max=10
設(shè)置最小的 pod 副本數(shù)為1，最大為10。HPA會(huì)根據(jù)設(shè)定的 cpu使用率（10%）動(dòng)態(tài)的增加或者減少pod數(shù)量。
$ kubectl get hpa
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS
hpa-nginx-deploy Deployment/hpa-nginx-deploy 0%/10% 1 10 1
$ kubectl get hpa hpa-nginx-deploy -o yaml
$ kubectl describe hpa hpa-nginx-deploy
6、用壓力測(cè)試查看hpa變化情況
$ kubectl get pod -o wide|grep hpa
hpa-nginx-deploy-7db6976d9b-p7llf 1/1 Running 0 155m 10.244.2.250 server242.example.com
$ kubectl run -i --tty load-generator --image=busybox /bin/sh
/ # while true; do wget -q -O- http://10.244.2.250; done
在另一個(gè)終端查看
$ kubectl get hpa
$ kubectl get deployment hpa-nginx-deploy
$ kubectl delete deployments.apps load-generator