第 3 章 公开用于自动扩展的自定义应用程序指标

您可以为 Pod 横向自动扩展导出自定义应用程序指标。

重要

Prometheus Adapter 只是技术预览功能。技术预览功能不被红帽产品服务等级协议 (SLA) 支持，且可能在功能方面有缺陷。红帽不推荐在生产环境中使用它们。这些技术预览功能可以使用户提早试用新的功能，并有机会在开发阶段提供反馈意见。

有关红帽技术预览功能支持范围的详情，请参阅 https://access.redhat.com/support/offerings/techpreview/。

3.1. 公开用于 Pod 横向自动扩展的自定义应用程序指标

您可以使用 prometheus-adapter 资源，为 Pod 横向自动扩展显示自定义应用程序指标。

先决条件

  • 确保安装了自定义 Prometheus 实例。本例中假定 Prometheus 已安装到 default 命名空间。
  • 确保为应用程序配置了监控功能。本例假定应用程序及服务监控器已安装到 default 命名空间。

流程

  1. 为您的配置创建一个 YAML 文件。本例中称为 deploy.yaml。

  2. 添加相应的配置，以便为 prometheus-adapter 创建服务帐户、必要角色和角色绑定： 

    kind: ServiceAccount
apiVersion: v1
metadata:
  name: custom-metrics-apiserver
  namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: custom-metrics-server-resources
rules:
- apiGroups:
  - custom.metrics.k8s.io
  resources: ["*"]
  verbs: ["*"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: custom-metrics-resource-reader
rules:
- apiGroups:
  - ""
  resources:
  - namespaces
  - pods
  - services
  verbs:
  - get
  - list
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: custom-metrics:system:auth-delegator
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:auth-delegator
subjects:
- kind: ServiceAccount
  name: custom-metrics-apiserver
  namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: custom-metrics-auth-reader
  namespace: kube-system
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccount
  name: custom-metrics-apiserver
  namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: custom-metrics-resource-reader
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: custom-metrics-resource-reader
subjects:
- kind: ServiceAccount
  name: custom-metrics-apiserver
  namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: hpa-controller-custom-metrics
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: custom-metrics-server-resources
subjects:
- kind: ServiceAccount
  name: horizontal-pod-autoscaler
  namespace: kube-system
---

  3. 添加 prometheus-adapter 的自定义指标的配置: 

    apiVersion: v1
kind: ConfigMap
metadata:
  name: adapter-config
  namespace: default
data:
  config.yaml: |
    rules:
    - seriesQuery: 'http_requests_total{namespace!="",pod!=""}' 1
      resources:
        overrides:
          namespace: {resource: "namespace"}
          pod: {resource: "pod"}
          service: {resource: "service"}
      name:
        matches: "^(.*)_total"
        as: "${1}_per_second" 2
      metricsQuery: 'sum(rate(<<.Series>>{<<.LabelMatchers>>}[2m])) by (<<.GroupBy>>)'
---
    1
    将所选指标指定为 HTTP 请求数。
    2
    指定指标的频率。

  4. 添加将 prometheus-adapter 注册为 API 服务的配置： 

    apiVersion: v1
kind: Service
metadata:
  annotations:
    service.alpha.openshift.io/serving-cert-secret-name: prometheus-adapter-tls
  labels:
    name: prometheus-adapter
  name: prometheus-adapter
  namespace: default
spec:
  ports:
  - name: https
    port: 443
    targetPort: 6443
  selector:
    app: prometheus-adapter
  type: ClusterIP
---
apiVersion: apiregistration.k8s.io/v1beta1
kind: APIService
metadata:
  name: v1beta1.custom.metrics.k8s.io
spec:
  service:
    name: prometheus-adapter
    namespace: default
  group: custom.metrics.k8s.io
  version: v1beta1
  insecureSkipTLSVerify: true
  groupPriorityMinimum: 100
  versionPriority: 100
---

  5. 显示要使用的 Prometheus Adapter 镜像： 

    $ kubectl get -n openshift-monitoring deploy/prometheus-adapter -o jsonpath="{..image}"
quay.io/openshift-release-dev/ocp-v4.3-art-dev@sha256:76db3c86554ad7f581ba33844d6a6ebc891236f7db64f2d290c3135ba81c264c

  6. 添加部署 prometheus-adapter 的配置： 

    apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: prometheus-adapter
  name: prometheus-adapter
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: prometheus-adapter
  template:
    metadata:
      labels:
        app: prometheus-adapter
      name: prometheus-adapter
    spec:
      serviceAccountName: custom-metrics-apiserver
      containers:
      - name: prometheus-adapter
        image: openshift-release-dev/ocp-v4.3-art-dev 1
        args:
        - --secure-port=6443
        - --tls-cert-file=/var/run/serving-cert/tls.crt
        - --tls-private-key-file=/var/run/serving-cert/tls.key
        - --logtostderr=true
        - --prometheus-url=http://prometheus-operated.default.svc:9090/
        - --metrics-relist-interval=1m
        - --v=4
        - --config=/etc/adapter/config.yaml
        ports:
        - containerPort: 6443
        volumeMounts:
        - mountPath: /var/run/serving-cert
          name: volume-serving-cert
          readOnly: true
        - mountPath: /etc/adapter/
          name: config
          readOnly: true
        - mountPath: /tmp
          name: tmp-vol
      volumes:
      - name: volume-serving-cert
        secret:
          secretName: prometheus-adapter-tls
      - name: config
        configMap:
          name: adapter-config
      - name: tmp-vol
        emptyDir: {}
    1
    image: openshift-release-dev/ocp-v4.3-art-dev 指定上一步中找到的 Prometheus Adapter 镜像。

  7. 将配置文件应用到集群： 

    $ oc apply -f deploy.yaml
  8. 现在，应用程序的指标已经公开，并可用于配置 Pod 横向自动扩展。

其他资源