本文主要是介绍kubernetes中的附件组件Metrics-server与hpa资源实现对pod的自动扩容和缩容，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
一、概述
Metrics-Server组件目的：获取集群中pod、节点等负载信息；
hpa资源目的：通过metrics-server获取的pod负载信息，自动伸缩创建pod；
二、安装部署 Metrics-Server组件
安装目的，就是给k8s集群安装top命令
1、下载Metrics-Server资源清单
wget https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/high-availability-1.21+.yaml
下载好的 high-availability-1.21+.yaml文件
apiVersion: v1
kind: ServiceAccount
metadata:labels:k8s-app: metrics-servername: metrics-servernamespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:labels:k8s-app: metrics-serverrbac.authorization.k8s.io/aggregate-to-admin: "true"rbac.authorization.k8s.io/aggregate-to-edit: "true"rbac.authorization.k8s.io/aggregate-to-view: "true"name: system:aggregated-metrics-reader
rules:
- apiGroups:- metrics.k8s.ioresources:- pods- nodesverbs:- get- list- watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:labels:k8s-app: metrics-servername: system:metrics-server
rules:
- apiGroups:- ""resources:- nodes/metricsverbs:- get
- apiGroups:- ""resources:- pods- nodesverbs:- get- list- watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:labels:k8s-app: metrics-servername: metrics-server-auth-readernamespace: kube-system
roleRef:apiGroup: rbac.authorization.k8s.iokind: Rolename: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccountname: metrics-servernamespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:labels:k8s-app: metrics-servername: metrics-server:system:auth-delegator
roleRef:apiGroup: rbac.authorization.k8s.iokind: ClusterRolename: system:auth-delegator
subjects:
- kind: ServiceAccountname: metrics-servernamespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:labels:k8s-app: metrics-servername: system:metrics-server
roleRef:apiGroup: rbac.authorization.k8s.iokind: ClusterRolename: system:metrics-server
subjects:
- kind: ServiceAccountname: metrics-servernamespace: kube-system
---
apiVersion: v1
kind: Service
metadata:labels:k8s-app: metrics-servername: metrics-servernamespace: kube-system
spec:ports:- name: httpsport: 443protocol: TCPtargetPort: httpsselector:k8s-app: metrics-server
---
apiVersion: apps/v1
kind: Deployment
metadata:labels:k8s-app: metrics-servername: metrics-servernamespace: kube-system
spec:replicas: 2selector:matchLabels:k8s-app: metrics-serverstrategy:rollingUpdate:maxUnavailable: 1template:metadata:labels:k8s-app: metrics-serverspec:affinity:podAntiAffinity:requiredDuringSchedulingIgnoredDuringExecution:- labelSelector:matchLabels:k8s-app: metrics-servernamespaces:- kube-systemtopologyKey: kubernetes.io/hostnamecontainers:- args:- --cert-dir=/tmp- --secure-port=10250- --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname- --kubelet-use-node-status-port- --metric-resolution=15simage: registry.k8s.io/metrics-server/metrics-server:v0.7.1imagePullPolicy: IfNotPresentlivenessProbe:failureThreshold: 3httpGet:path: /livezport: httpsscheme: HTTPSperiodSeconds: 10name: metrics-serverports:- containerPort: 10250name: httpsprotocol: TCPreadinessProbe:failureThreshold: 3httpGet:path: /readyzport: httpsscheme: HTTPSinitialDelaySeconds: 20periodSeconds: 10resources:requests:cpu: 100mmemory: 200MisecurityContext:allowPrivilegeEscalation: falsecapabilities:drop:- ALLreadOnlyRootFilesystem: truerunAsNonRoot: truerunAsUser: 1000seccompProfile:type: RuntimeDefaultvolumeMounts:- mountPath: /tmpname: tmp-dirnodeSelector:kubernetes.io/os: linuxpriorityClassName: system-cluster-criticalserviceAccountName: metrics-servervolumes:- emptyDir: {}name: tmp-dir
---
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:labels:k8s-app: metrics-servername: metrics-servernamespace: kube-system
spec:minAvailable: 1selector:matchLabels:k8s-app: metrics-server
---
apiVersion: apiregistration.k8s.io/v1
kind: APIService
metadata:labels:k8s-app: metrics-servername: v1beta1.metrics.k8s.io
spec:group: metrics.k8s.iogroupPriorityMinimum: 100insecureSkipTLSVerify: trueservice:name: metrics-servernamespace: kube-systemversion: v1beta1versionPriority: 100
2、编辑Metrics-Server的资源清单
.... topologyKey: kubernetes.io/hostnamecontainers:- args:#启动允许使用不安全的证书- --kubelet-insecure-tls- --cert-dir=/tmp- --secure-port=10250- --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname- --kubelet-use-node-status-port- --metric-resolution=15s#image: registry.k8s.io/metrics-server/metrics-server:v0.7.1image: registry.aliyuncs.com/google_containers/metrics-server:v0.6.3imagePullPolicy: IfNotPresentlivenessProbe:failureThreshold: 3httpGet:path: /livez....
3、创建Metrics-Server资源
[root@master study-demo]# kubectl apply -f high-availability-1.21+.yaml
serviceaccount/metrics-server created
clusterrole.rbac.authorization.k8s.io/system:aggregated-metrics-reader created
clusterrole.rbac.authorization.k8s.io/system:metrics-server created
rolebinding.rbac.authorization.k8s.io/metrics-server-auth-reader created
clusterrolebinding.rbac.authorization.k8s.io/metrics-server:system:auth-delegator created
clusterrolebinding.rbac.authorization.k8s.io/system:metrics-server created
service/metrics-server created
deployment.apps/metrics-server created
poddisruptionbudget.policy/metrics-server created
apiservice.apiregistration.k8s.io/v1beta1.metrics.k8s.io created
4、查看安装结果
4.1 查看pod
[root@master study-demo]# kubectl get pod --show-labels -A | grep metrics
4.2 kubectl top node 命令查看节点信息
4.3 kubectl top pods -A 命令查看pod信息
三、hpa资源实现pod水平伸缩（自动扩缩容）
- 当资源使用超过一定的范围，会自动扩容，但是扩容数量不会超过最大pod数量
- 扩容时无延迟，只要监控资源超过阈值，则会自动创建pod
- 当资源使用率恢复到阈值以下时，需要等待一段时间才会释放，大概5分钟
3.1 编写deployment资源清单
[root@master hpa-demo]# cat deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: dm-hpa
spec:
replicas: 1
selector:
matchLabels:
k8s: dolphin
template:
metadata:
labels:
k8s: dolphin
spec:
containers:
- name: c1
image: centos:7
command:
- tail
- -f
- /etc/hosts
resources:
requests:
cpu: "50m"
limits:
cpu: "150m"
3.2 编写hpa资源清单绑定deployment
[root@master hpa-demo]# cat hpa.yaml
apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
name: hpa-tools
spec:
maxReplicas: 10 # 扩容上线
minReplicas: 2 # 缩容下限
scaleTargetRef: # 扩缩容的目标
apiVersion: "apps/v1"
kind: Deployment
name: dm-hpa
targetCPUUtilizationPercentage: 95 #cpu阈值达到95%开始扩缩容
3.3 创建上面两个资源
[root@master hpa-demo]# kubectl apply -f deployment.yaml
[root@master hpa-demo]# kubectl apply -f hpa.yaml
3.4 查看hpa资源
可以看到我们deployment.yaml文件中的副本是1，创建hap绑定资源后，会根据hpa的配置，这里配置了2个，所以就创建了2个pod资源。
四、压测测试
1，进入pod，安装stress工具
· 进入pod容器
[root@master hpa]# kubectl exec dm-hpa-5bb4dd448d-ks2rt -it -- sh
· 安装aili源和epel源
sh-4.2# yum -y install wget
sh-4.2# wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
sh-4.2# wget -O /etc/yum.repos.d/epel.repo https://mirrors.aliyun.com/repo/epel-7.repo
· 安装压测工具
sh-4.2# yum -y install stress
2，开始使用命令压测pod
sh-4.2# stress --cpu 8 --io 4 --vm 2 --vm-bytes 128M --timeout 20m
3，查看hpa资源的负载情况
[root@master ~]# kubectl get hpa -o wide
可以看到：
1，我们创建的deploy资源只有一个副本；
2，我们创建的hpa资源之后，设置最小值是2，最大值是10 ；
3，我们在查看pod，可以看见，pod变成了2个；
4，我们进入容器，开始压测，将负载压测到超过95%；
5，再次查看pod，发现变成了3个，自动创建了一个；
6，关闭压测，5分钟后，pod有回归到了2个；
7，至此，hpa的pod自动伸缩，测试完毕；
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