前言

Metrics Server是Kubernetes內置自動伸縮管道的一個可伸縮、高效的容器資源度量來源。

Metrics Server從Kubelets收集資源指標，并通過Metrics API將它們暴露在Kubernetes apiserver中，供水平Pod Autoscaler和垂直Pod Autoscaler使用。kubectl top還可以訪問Metrics API，這使得調試自動伸縮管道變得更容易。

Metrics Server不是用于非自動伸縮的目的。例如，不要將其用于將指標轉發給監視解決方案，或者作為監視解決方案指標的來源。在這種情況下，請直接從Kubelet /metrics/resource端點收集度量。

Metrics Server提供

• 在大多數集群上工作的單個部署
• 快速自動縮放，每15秒收集一次指標。
• 資源效率，為集群中的每個節點使用1毫秒的CPU內核和2 MB的內存。
• 可擴展支持多達5000個節點群集。

一、Metrics Server 與 kubenetes版本

更多的詳細資料，請前往github官網查看。

二、Metrics Server 下載方式

github：https://github.com/kubernetes-sigs/metrics-server

三、k8s集群安裝部署metrics

本次我們安裝的是metrics0.5.0版本
下載地址：https://github.com/kubernetes-sigs/metrics-server/releases
docker鏡像地址：docker pull cnskylee/metrics-server:v0.5.0

1. 在k8s集群里面下載metrics-server鏡像，保證每一臺主機都能都訪問到鏡像

#下載鏡像
docker pull cnskylee/metrics-server:v0.5.0
#修改標簽
docker tag cnskylee/metrics-server:v0.5.0 k8s.gcr.io/metrics-server/metrics-server:v0.5.0

2. 創建components-v0.5.0.yaml文件，并將下面的腳本copy到文件中

apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    k8s-app: metrics-server
    rbac.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.io
  resources:
  - pods
  - nodes
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    k8s-app: metrics-server
  name: system:metrics-server
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - nodes
  - nodes/stats
  - namespaces
  - configmaps
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server-auth-reader
  namespace: kube-system
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server:system:auth-delegator
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:auth-delegator
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: system:metrics-server
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:metrics-server
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: v1
kind: Service
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
spec:
  ports:
  - name: https
    port: 443
    protocol: TCP
    targetPort: https
  selector:
    k8s-app: metrics-server
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
spec:
  selector:
    matchLabels:
      k8s-app: metrics-server
  strategy:
    rollingUpdate:
      maxUnavailable: 0
  template:
    metadata:
      labels:
        k8s-app: metrics-server
    spec:
      containers:
      - args:
        - --cert-dir=/tmp
        - --secure-port=443
        - --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname
        - --kubelet-use-node-status-port
        - --metric-resolution=15s
        - --kubelet-insecure-tls
        image: k8s.gcr.io/metrics-server/metrics-server:v0.5.0
        imagePullPolicy: IfNotPresent
        livenessProbe:
          failureThreshold: 3
          httpGet:
            path: /livez
            port: https
            scheme: HTTPS
          periodSeconds: 10
        name: metrics-server
        ports:
        - containerPort: 443
          name: https
          protocol: TCP
        readinessProbe:
          failureThreshold: 3
          httpGet:
            path: /readyz
            port: https
            scheme: HTTPS
          initialDelaySeconds: 20
          periodSeconds: 10
        resources:
          requests:
            cpu: 100m
            memory: 200Mi
        securityContext:
          readOnlyRootFilesystem: true
          runAsNonRoot: true
          runAsUser: 1000
        volumeMounts:
        - mountPath: /tmp
          name: tmp-dir
      nodeSelector:
        kubernetes.io/os: linux
      priorityClassName: system-cluster-critical
      serviceAccountName: metrics-server
      volumes:
      - emptyDir: {}
        name: tmp-dir
---
apiVersion: apiregistration.k8s.io/v1
kind: APIService
metadata:
  labels:
    k8s-app: metrics-server
  name: v1beta1.metrics.k8s.io
spec:
  group: metrics.k8s.io
  groupPriorityMinimum: 100
  insecureSkipTLSVerify: true
  service:
    name: metrics-server
    namespace: kube-system
  version: v1beta1
  versionPriority: 100

3. 執行安裝

kubectl apply -f ./components-v0.5.0.yaml

4.查看metrics-server的pod運行狀態

kubectl get pods -n kube-system| egrep 'NAME|metrics-server'

5.測試kubectl top命令的使用

kubectl top pods -n kube-system