说明：

集群部署好后，如果想使用kubectl top node/pod来查看资源使用情况，需要我们部署对应api资源才可以使用此命令。从 Kubernetes 1.8 开始，资源使用指标（如容器 CPU 和内存使用率）通过 Metrics API 在 Kubernetes 中获取, metrics-server 替代了heapster。
配套k8s版本：

Metrics Server	Metrics API group/version	Supported Kubernetes version
0.6.x	metrics.k8s.io/v1beta1	*1.19+
0.5.x	metrics.k8s.io/v1beta1	*1.8+
0.4.x	metrics.k8s.io/v1beta1	*1.8+
0.3.x	metrics.k8s.io/v1beta1	1.8-1.21

具体步骤如下：

下载mertics-server资源描述文件：

从github的metrics-server项目下载，
项目地址: https://github.com/kubernetes-sigs/metrics-server
最新mertics-server资源描述文件下载：
最新文件地址: https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
默认可以直接使用远程文件部署mertics-server，命令如下：

• 单实例版本(非高可用)

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

• 高可用版本：

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/high-availability.yaml

但是由于文件中的镜像使用的是国外仓库，无法下载，只能先将镜像下载到本地，资源描述文件也下载到本地，便于修改镜像配置和启动参数

修改mertics-server资源描述文件文件

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							#增加选项，不验证客户端证书
        image: k8s.gcr.io/metrics-server/metrics-server:v0.5.0	#根据本地实际镜像仓库修改
        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

导入镜像：

从网上下载metrics-server镜像文件（我用的是0.5.0），导入到多个node节点（未搭建本地仓库），如果搭建了本地仓库，可以直接推送到仓库
注意：导入镜像时注意选择命令：我下载的镜像需要使用 docker load 命令导入

docker load -i 镜像文件名

采坑如下：
使用import命令导入镜像，部署启动后报错：

导入后镜像仓库与资源描述文件一致：

部署metrics-server：

master节点使用kubectl apply -f [文件名] 部署

 kubectl apply -f metrics-server.yaml

部署完成后：
node节点上运行metrics-server pod：

可以执行kubectl top命令查看资源使用情况：

注：如果失败，删除metrics-server资源：

 kubectl delete -f metrics-server.yaml