【Kubernetes】Kubernetes 集群开启 Metrics-Server

Metrics-Server 是 Kubernetes 集群中的一个核心组件，负责收集和聚合集群中节点和 Pod 的资源使用指标（如 CPU 和内存使用情况），这些指标对于集群自动扩缩容（如  HPA）和集群监控至关重要，一起来看看如何开启吧！

1、主要功能

• 资源监控：收集节点和 Pod 的 CPU、内存使用情况
• 指标聚合：将原始指标数据聚合为可用的 API 格式
• API 提供：通过 Kubernetes Metrics API 提供指标数据
• 高效轻量：设计为轻量级组件，对集群性能影响小

2、工作原理

• 数据收集：定期从每个节点上的 kubelet 收集资源使用指标
• 数据存储：在内存中短期存储这些指标（不持久化）
• API 暴露：通过 K8s 的 Metrics API （通常是 metrics.k8s.io/v1beta1）暴露数据
• 数据消费：HPA、kubectl top 等组件通过这个 API 获取指标

3、安装

# GitHub 地址为 
https://github.com/kubernetes-sigs/metrics-server

# 下载 YAML 文件
wget https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
# 修改镜像为阿里云镜像
sed -i 's|registry.k8s.io/metrics-server/metrics-server|registry.aliyuncs.com/google_containers/metrics-server|g' components.yaml
# 应用 YAML 文件
kubectl apply -f components.yaml
# 测试部署成功
kubectl top pod -n kube-system

# 其他基础命令
# 显示 default 命名空间下所有 Pods 的指标
kubectl top pod
# 显示指定命名空间下所有 Pods 的指标
kubectl top pod -A
# 显示指定 Pod 和它的容器的 metrics
kubectl top pod POD_NAME --containers
# 显示指定 label 为 name=myLabel 的 Pods 的 metrics
kubectl top pod -l name=myLabel

# 报错："Failed to scrape node" err="Get \"https://x.x.x.x:10250/metrics/resource\": tls: failed to verify certificate: x509: cannot validate certificate for x.x.x.x because it doesn't contain any IP SANs" node="master"
# 解决：修改 Metrics-Server 的 Deployment 添加 --kubelet-insecure-tls 参数
kubectl -n kube-system edit deployment metrics-server
...
args:
  - --kubelet-insecure-tls
  # 其他原有参数
...

• metrics-server 版本与 k8s 版本对应关系

4、完整 YAML 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:
  - nodes/metrics
  verbs:
  - get
- apiGroups:
  - ""
  resources:
  - pods
  - nodes
  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:
        - --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.aliyuncs.com/google_containers/metrics-server:v0.7.2
        imagePullPolicy: IfNotPresent
        livenessProbe:
          failureThreshold: 3
          httpGet:
            path: /livez
            port: https
            scheme: HTTPS
          periodSeconds: 10
        name: metrics-server
        ports:
        - containerPort: 10250
          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:
          allowPrivilegeEscalation: false
          capabilities:
            drop:
            - ALL
          readOnlyRootFilesystem: true
          runAsNonRoot: true
          runAsUser: 1000
          seccompProfile:
            type: RuntimeDefault
        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