kube-state-metrics组件

• kube-state-metrics：kube-state-metrics 通过监听 API Server 生成有关资源对象的状态指标，比如 Deployment、Node、Pod，需要注意的是 kube-state-metrics 只是简单提供一个 metrics 数据，并不会存储这些指标数据，所以我们可以使用 Prometheus 来抓取这些数据然后存储。

kube-state-metrics 和 metrics-server 之间还是有很大不同的，二者的主要区别如下：

• kube-state-metrics 主要关注的是业务相关的一些元数据，比如 Deployment、Pod、副本状态等
• metrics-server 主要关注的是资源度量 API 的实现，比如 CPU、文件描述符、内存、请求延时等指标。

部署kube-state-metrics

cluster-role.yaml

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    app.kubernetes.io/component: exporter
    app.kubernetes.io/name: kube-state-metrics
    app.kubernetes.io/version: 2.3.0
  name: kube-state-metrics
rules:
- apiGroups:
  - ""
  resources:
  - configmaps
  - secrets
  - nodes
  - pods
  - services
  - resourcequotas
  - replicationcontrollers
  - limitranges
  - persistentvolumeclaims
  - persistentvolumes
  - namespaces
  - endpoints
  verbs:
  - list
  - watch
- apiGroups:
  - apps
  resources:
  - statefulsets
  - daemonsets
  - deployments
  - replicasets
  verbs:
  - list
  - watch
- apiGroups:
  - batch
  resources:
  - cronjobs
  - jobs
  verbs:
  - list
  - watch
- apiGroups:
  - autoscaling
  resources:
  - horizontalpodautoscalers
  verbs:
  - list
  - watch
- apiGroups:
  - authentication.k8s.io
  resources:
  - tokenreviews
  verbs:
  - create
- apiGroups:
  - authorization.k8s.io
  resources:
  - subjectaccessreviews
  verbs:
  - create
- apiGroups:
  - policy
  resources:
  - poddisruptionbudgets
  verbs:
  - list
  - watch
- apiGroups:
  - certificates.k8s.io
  resources:
  - certificatesigningrequests
  verbs:
  - list
  - watch
- apiGroups:
  - storage.k8s.io
  resources:
  - storageclasses
  - volumeattachments
  verbs:
  - list
  - watch
- apiGroups:
  - admissionregistration.k8s.io
  resources:
  - mutatingwebhookconfigurations
  - validatingwebhookconfigurations
  verbs:
  - list
  - watch
- apiGroups:
  - networking.k8s.io
  resources:
  - networkpolicies
  - ingresses
  verbs:
  - list
  - watch
- apiGroups:
  - coordination.k8s.io
  resources:
  - leases
  verbs:
  - list
  - watch

cluster-role-binding.yaml

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    app.kubernetes.io/component: exporter
    app.kubernetes.io/name: kube-state-metrics
    app.kubernetes.io/version: 2.3.0
  name: kube-state-metrics
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: kube-state-metrics
subjects:
- kind: ServiceAccount
  name: kube-state-metrics
  namespace: kube-system

service-account.yaml

apiVersion: v1
automountServiceAccountToken: false
kind: ServiceAccount
metadata:
  labels:
    app.kubernetes.io/component: exporter
    app.kubernetes.io/name: kube-state-metrics
    app.kubernetes.io/version: 2.3.0
  name: kube-state-metrics
  namespace: kube-system

service.yaml

apiVersion: v1
kind: Service
metadata:
  labels:
    app.kubernetes.io/component: exporter
    app.kubernetes.io/name: kube-state-metrics
    app.kubernetes.io/version: 2.3.0
  name: kube-state-metrics
  namespace: kube-system
spec:
  clusterIP: None
  ports:
  - name: http-metrics
    port: 8080
    targetPort: http-metrics
  - name: telemetry
    port: 8081
    targetPort: telemetry
  selector:
    app.kubernetes.io/name: kube-state-metrics

deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app.kubernetes.io/component: exporter
    app.kubernetes.io/name: kube-state-metrics
    app.kubernetes.io/version: 2.3.0
  name: kube-state-metrics
  namespace: kube-system
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: kube-state-metrics
  template:
    metadata:
      labels:
        app.kubernetes.io/component: exporter
        app.kubernetes.io/name: kube-state-metrics
        app.kubernetes.io/version: 2.3.0
    spec:
      automountServiceAccountToken: true
      containers:
      - image: bitnami/kube-state-metrics:latest
        livenessProbe:
          httpGet:
            path: /healthz
            port: 8080
          initialDelaySeconds: 5
          timeoutSeconds: 5
        name: kube-state-metrics
        ports:
        - containerPort: 8080
          name: http-metrics
        - containerPort: 8081
          name: telemetry
        readinessProbe:
          httpGet:
            path: /
            port: 8081
          initialDelaySeconds: 5
          timeoutSeconds: 5
        securityContext:
          allowPrivilegeEscalation: false
          readOnlyRootFilesystem: true
          runAsUser: 65534
      nodeSelector:
        kubernetes.io/os: linux
      serviceAccountName: kube-state-metrics

Kube-state-metrics:通过监听API Server生成有关资源对象的状态指标，比如Deployment、Node、Pod，需要注意的是kube-state-metrics只是简单的提供一个metrics数据，并不会存储这些指标数据，所以我们可以使用Prometheus来抓取这些数据然后存储，主要关注的是业务相关的一些元数据，比如Deployment、Pod、副本状态等；调度了多少个replicas？现在可用的有几个？；多少个Pod是running/stopped/terminated状态？；Pod重启了多少次？；我有多少job在运行中。

Kube-state-metrics和metrics-server对比

• metric-server是从api-server中获取cpu、内存使用率这种监控指标，并把他们发送给存储后端，如influxdb或云厂商，他当前的核心作用是：为HPA等组件提供决策指标支持。
• kube-state-metrics关注于获取k8s各种资源的最新状态，如deployment或者daemonset，之所以没有把kube-state-metrics纳入到metric-server的能力中，是因为他们的关注点本质上是不一样的。metric-server仅仅是获取、格式化现有数据，写入特定的存储，实质上是一个监控系统。而kube-state-metrics是将k8s的运行状况在内存中做了个快照，并且获取新的指标，但他没有能力导出这些指标
• 换个角度讲，kube-state-metrics本身是metric-server的一种数据来源，虽然现在没有这么做。
• 另外，像Prometheus这种监控系统，并不会去用metric-server中的数据，他都是自己做指标收集、集成的（Prometheus包含了metric-server的能力），但Prometheus可以监控metric-server本身组件的监控状态并适时报警，这里的监控就可以通过kube-state-metrics来实现，如metric-serverpod的运行状态。