前言

各位老铁大家好，好久不见，卑微涛目前从事kubernetes相关容器工作，感兴趣的小伙伴相互交流一下鸭~

一、表象

使用kubeadm、二进制方式安装的K8S，想查看集群中，node节点/pod的CUP、内存等信息，无法查看

报错：Error from server (ServiceUnavailable): the server is currently unable to handle the request (get pods.metrics.k8s.io)

原因是：缺少metrics-server这个pod

二、解决方法

下面咱们手把手解决这个问题

1、导入镜像包

导入下列两个镜像包

镜像包链接：【若链接失效请私聊卑微涛】
链接：https://pan.baidu.com/s/1qo6QTqF9xSEfeN9OS9BjdQ
提取码：gjx4

#如果k8s是 docker 作为 容器运行时
docker image load -i addon.tar.gz
docker image load -i metrics-server-amd64-0-3-6.tar.gz

#如果k8s是 container 作为 容器运行时
ctr -n=k8s.io images import addon.tar.gz
ctr -n=k8s.io images import metrics-server-amd64-0-3-6.tar.gz
#==================================================================
#查看k8s是哪个作为 容器运行时
kubectl get node -o wide

2、编辑yaml文件

注意修改对应的 images：xxx 镜像名称，其余配置无需修改

# cat metrics.yaml			#这个yaml文件在镜像包对应的目录中有，大家下载也行
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: metrics-server:system:auth-delegator
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
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: RoleBinding
metadata:
  name: metrics-server-auth-reader
  namespace: kube-system
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: metrics-server
  namespace: kube-system
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: system:metrics-server
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - nodes
  - nodes/stats
  - namespaces
  verbs:
  - get
  - list
  - watch
- apiGroups:
  - "extensions"
  resources:
  - deployments
  verbs:
  - get
  - list
  - update
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: system:metrics-server
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:metrics-server
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: metrics-server-config
  namespace: kube-system
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: EnsureExists
data:
  NannyConfiguration: |-
    apiVersion: nannyconfig/v1alpha1
    kind: NannyConfiguration
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: metrics-server
  namespace: kube-system
  labels:
    k8s-app: metrics-server
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
    version: v0.3.6
spec:
  selector:
    matchLabels:
      k8s-app: metrics-server
      version: v0.3.6
  template:
    metadata:
      name: metrics-server
      labels:
        k8s-app: metrics-server
        version: v0.3.6
    spec:
      priorityClassName: system-cluster-critical
      serviceAccountName: metrics-server
      containers:
      - name: metrics-server
        image: k8s.gcr.io/metrics-server-amd64:v0.3.6		#这里的镜像名称，根据导入的镜像包修改
        imagePullPolicy: IfNotPresent
        command:
        - /metrics-server
        - --metric-resolution=30s
        - --kubelet-preferred-address-types=InternalIP
        - --kubelet-insecure-tls
        ports:
        - containerPort: 443
          name: https
          protocol: TCP
      - name: metrics-server-nanny
        image: k8s.gcr.io/addon-resizer:1.8.4			#这里的镜像名称，根据导入的镜像包修改
        imagePullPolicy: IfNotPresent
        resources:
          limits:
            cpu: 100m
            memory: 300Mi
          requests:
            cpu: 5m
            memory: 50Mi
        env:
          - name: MY_POD_NAME
            valueFrom:
              fieldRef:
                fieldPath: metadata.name
          - name: MY_POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
        volumeMounts:
        - name: metrics-server-config-volume
          mountPath: /etc/config
        command:
          - /pod_nanny
          - --config-dir=/etc/config
          - --cpu=300m
          - --extra-cpu=20m
          - --memory=200Mi
          - --extra-memory=10Mi
          - --threshold=5
          - --deployment=metrics-server
          - --container=metrics-server
          - --poll-period=300000
          - --estimator=exponential
          - --minClusterSize=2
      volumes:
        - name: metrics-server-config-volume
          configMap:
            name: metrics-server-config
      nodeSelector:
        galaxy-app: kce-monitor
      tolerations:
        - key: "CriticalAddonsOnly"
          operator: "Exists"
        - key: node-role.kubernetes.io/master
          effect: NoSchedule
---
apiVersion: v1
kind: Service
metadata:
  name: metrics-server
  namespace: kube-system
  labels:
    addonmanager.kubernetes.io/mode: Reconcile
    kubernetes.io/cluster-service: "true"
    kubernetes.io/name: "Metrics-server"
spec:
  selector:
    k8s-app: metrics-server
  ports:
  - port: 443
    protocol: TCP
    targetPort: https
---
apiVersion: apiregistration.k8s.io/v1
kind: APIService
metadata:
  name: v1beta1.metrics.k8s.io
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
spec:
  service:
    name: metrics-server
    namespace: kube-system
  group: metrics.k8s.io
  version: v1beta1
  insecureSkipTLSVerify: true
  groupPriorityMinimum: 100
  versionPriority: 100

kubectl apply -f metrics.yaml #运行这个yaml文件

3、解决问题

查看对应的pod是否正常运行

kubectl get deploy -n kube-system metrics-server

kubectl get pod -n kube-system |grep metrics-server

等待30秒，即可正常使用了

三、优化改造

作为一名"老运维"工程师（好吧，就2年😉）,优化+高可用是我们必须考虑的，有一次演练把这个pod删后，虽然重新拉起了，但kubectl top pod 又异常了，我们需要再做这么一个操作

1.修改配置文件

# 修改每个 API Server 的 kube-apiserver.yaml 配置开启 Aggregator Routing：修改 manifests 配置后 API Server 会自动重启生效。
$ cat /etc/kubernetes/manifests/kube-apiserver.yaml
spec:
  containers:
  - command:
  -  --enable-aggregator-routing=true		#增加这一行配置

注意：/etc/kubernetes/manifests这个目录下的文件由kubelet服务检测，是静态pod，修改完即可，不需要再kubectl apply -f 运行，会自动重新建立对应的pod

2.检查api-server服务是否正常

$ kubectl describe svc metrics-server -n kube-system

# 在其他几个节点ping一下Endpoints的地址
ping IP
telnet IP 443

3.测试验证

我们再测试一下，把metrics-server对应的pod删除后，是否能正常使用 kubectl top 指令

大功告成！

---

总结

"失踪"的一年多时间里，经历了很多，从数据库 --> 大数据 --> 容器，每一次改变，逼着自己跳出舒适圈，
感谢这一路的挫折，让我变得更Strong！

后续不断输出 容器&Kubernetes 相关博客

我是卑微涛，咱们下一篇文章再见了🤞