Prometheus Operator 高级配置(服务自动发现、

自动发现配置

1、定义配置jod（prometheus-additional.yaml）

$ cd /k8s-cmp/yaml/prometheus_Operator/kube-prometheus/manifests
$ vim prometheus-additional.yaml
- job_name: 'kubernetes-service-endpoints'
  kubernetes_sd_configs:
  - role: endpoints
  relabel_configs:
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scrape]
    action: keep
    regex: true
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scheme]
    action: replace
    target_label: __scheme__
    regex: (https?)
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_path]
    action: replace
    target_label: __metrics_path__
    regex: (.+)
  - source_labels: [__address__, __meta_kubernetes_service_annotation_prometheus_io_port]
    action: replace
    target_label: __address__
    regex: ([^:]+)(?::\d+)?;(\d+)
    replacement: $1:$2
  - action: labelmap
    regex: __meta_kubernetes_service_label_(.+)
  - source_labels: [__meta_kubernetes_namespace]
    action: replace
    target_label: kubernetes_namespace
  - source_labels: [__meta_kubernetes_service_name]
    action: replace
    target_label: kubernetes_name

2、创建jod的secret对象

$ kubectl create secret generic additional-configs --from-file=prometheus-additional.yaml -n monitoring
secret "additional-configs" created

3、声明 prometheus 的资源对象文件中添加上这个额外的配置：(prometheus-prometheus.yaml)

添加：
additionalScrapeConfigs:
name: additional-configs
key: prometheus-additional.yaml

apiVersion: monitoring.coreos.com/v1
kind: Prometheus
metadata:
  labels:
    prometheus: k8s
  name: k8s
  namespace: monitoring
spec:
  alerting:
    alertmanagers:
    - name: alertmanager-main
      namespace: monitoring
      port: web
  additionalScrapeConfigs:
    name: additional-configs
    key: prometheus-additional.yaml
  baseImage: quay.io/prometheus/prometheus
  nodeSelector:
    kubernetes.io/os: linux
  podMonitorSelector: {}
  replicas: 2
  resources:
    requests:
      memory: 400Mi
  ruleSelector:
    matchLabels:
      prometheus: k8s
      role: alert-rules
  securityContext:
    fsGroup: 2000
    runAsNonRoot: true
    runAsUser: 1000
  serviceAccountName: prometheus-k8s
  serviceMonitorNamespaceSelector: {}
  serviceMonitorSelector: {}
  version: v2.11.0

4、添加完成后，直接更新 prometheus 这个 CRD 资源对象：

$ kubectl apply -f prometheus-prometheus.yaml
prometheus.monitoring.coreos.com "k8s" configured

5、隔一小会儿，可以前往 Prometheus 的 Dashboard 中查看配置是否生效：

config

在 Prometheus Dashboard 的配置页面下面我们可以看到已经有了对应的的配置信息了，但是我们切换到 targets 页面下面却并没有发现对应的监控任务，查看 Prometheus 的 Pod 日志：

$ kubectl logs -f prometheus-k8s-0 prometheus -n monitoring
level=error ts=2018-12-20T15:14:06.772903214Z caller=main.go:240 component=k8s_client_runtime err="github.com/prometheus/prometheus/discovery/kubernetes/kubernetes.go:302: Failed to list *v1.Pod: pods is forbidden: User \"system:serviceaccount:monitoring:prometheus-k8s\" cannot list pods at the cluster scope"
level=error ts=2018-12-20T15:14:06.773096875Z caller=main.go:240 component=k8s_client_runtime err="github.com/prometheus/prometheus/discovery/kubernetes/kubernetes.go:301: Failed to list *v1.Service: services is forbidden: User \"system:serviceaccount:monitoring:prometheus-k8s\" cannot list services at the cluster scope"
level=error ts=2018-12-20T15:14:06.773212629Z caller=main.go:240 component=k8s_client_runtime err="github.com/prometheus/prometheus/discovery/kubernetes/kubernetes.go:300: Failed to list *v1.Endpoints: endpoints is forbidden: User \"system:serviceaccount:monitoring:prometheus-k8s\" cannot list endpoints at the cluster scope"
......

可以看到有很多错误日志出现，都是xxx is forbidden，这说明是 RBAC 权限的问题，通过 prometheus 资源对象的配置可以知道 Prometheus 绑定了一个名为 prometheus-k8s 的 ServiceAccount 对象，而这个对象绑定的是一个名为 prometheus-k8s 的 ClusterRole。
6、修改 prometheus-k8s 的 ClusterRole（prometheus-clusterRole.yaml）

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: prometheus-k8s
rules:
- apiGroups:
  - ""
  resources:
  - nodes
  - services
  - endpoints
  - pods
  - nodes/proxy
  verbs:
  - get
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - configmaps
  - nodes/metrics
  verbs:
  - get
- nonResourceURLs:
  - /metrics
  verbs:
  - get

更新上面的 ClusterRole 这个资源对象，然后重建下 Prometheus 的所有 Pod，正常就可以看到 targets 页面下面有 kubernetes-service-endpoints 这个监控任务了：

$ kubectl get pod -n monitoring
NAME                                   READY   STATUS    RESTARTS   AGE
···
prometheus-k8s-0                       3/3     Running   1          87m
prometheus-k8s-1                       3/3     Running   1          87m
···
$ kubectl delete pod prometheus-k8s-0 -n monitoring
$ kubectl delete pod prometheus-k8s-1 -n monitoring

image.png

这里自动监控了两个 Service，第一个是之前创建的 Redis 的服务，在 Redis Service 中有两个特殊的 annotations：

annotations:
  prometheus.io/scrape: "true"
  prometheus.io/port: "9121"

所以被自动发现了，当然也可以用同样的方式去配置 Pod、Ingress 这些资源对象的自动发现。

数据持久化

在修改完权限的时候，重启了 Prometheus 的 Pod，会发现之前采集的数据已经没有了，这是因为通过 prometheus 这个 CRD 创建的 Prometheus 并没有做数据的持久化，查看生成的 Prometheus Pod 的挂载情况就清楚了：

$ kubectl get pod prometheus-k8s-0 -n monitoring -o yaml
......
    volumeMounts:
    - mountPath: /etc/prometheus/config_out
      name: config-out
      readOnly: true
    - mountPath: /prometheus
      name: prometheus-k8s-db
......
  volumes:
......
  - emptyDir: {}
    name: prometheus-k8s-db
......

可以看到 Prometheus 的数据目录 /prometheus 实际上是通过 emptyDir 进行挂载的， emptyDir 挂载的数据的生命周期和 Pod 生命周期一致的，所以如果 Pod 挂掉了，数据也就丢失了，这也就是为什么重建 Pod 后之前的数据就没有了的原因，对应线上的监控数据肯定需要做数据的持久化的，同样的 prometheus 这个 CRD 资源提供了数据持久化的配置方法，Prometheus 最终是通过 Statefulset 控制器进行部署的，所以需要通过 storageclass 来做数据持久化。
1、创建一个 StorageClass 对象（ prometheus-storageclass.yaml）

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: prometheus-data-db
provisioner: fuseim.pri/ifs

2、在 prometheus 的 CRD 资源对象中添加如下配置：（prometheus-prometheus.yaml）

添加
storage:
volumeClaimTemplate:
spec:
storageClassName: prometheus-data-db
resources:
requests:
storage: 10Gi

apiVersion: monitoring.coreos.com/v1
kind: Prometheus
metadata:
  labels:
    prometheus: k8s
  name: k8s
  namespace: monitoring
spec:
  alerting:
    alertmanagers:
    - name: alertmanager-main
      namespace: monitoring
      port: web
  additionalScrapeConfigs:
    name: additional-configs
    key: prometheus-additional.yaml
  storage:
    volumeClaimTemplate:
      spec:
        storageClassName: prometheus-data-db
        resources:
          requests:
            storage: 16Gi
  baseImage: quay.io/prometheus/prometheus
  nodeSelector:
    kubernetes.io/os: linux
  podMonitorSelector: {}
  replicas: 2
  resources:
    requests:
      memory: 400Mi
  ruleSelector:
    matchLabels:
      prometheus: k8s
      role: alert-rules
  securityContext:
    fsGroup: 2000
    runAsNonRoot: true
    runAsUser: 1000
  serviceAccountName: prometheus-k8s
  serviceMonitorNamespaceSelector: {}
  serviceMonitorSelector: {}
  version: v2.11.0

注意这里的 storageClassName 名字为上面创建的 StorageClass 对象名称，然后更新 prometheus 这个 CRD 资源。更新完成后会自动生成两个 PVC 和 PV 资源对象：

$ kubectl get pvc -n monitoring
NAME                                 STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS         AGE
prometheus-k8s-db-prometheus-k8s-0   Bound     pvc-0cc03d41-047a-11e9-a777-525400db4df7   10Gi       RWO            prometheus-data-db   8m
prometheus-k8s-db-prometheus-k8s-1   Bound     pvc-1938de6b-047b-11e9-a777-525400db4df7   10Gi       RWO            prometheus-data-db   1m
$ kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                                           STORAGECLASS         REASON    AGE
pvc-0cc03d41-047a-11e9-a777-525400db4df7   10Gi       RWO            Delete           Bound       monitoring/prometheus-k8s-db-prometheus-k8s-0   prometheus-data-db             2m
pvc-1938de6b-047b-11e9-a777-525400db4df7   10Gi       RWO            Delete           Bound       monitoring/prometheus-k8s-db-prometheus-k8s-1   prometheus-data-db             1m

3、查看 Prometheus Pod 的数据目录就可以看到是关联到一个 PVC 对象上了。

$ kubectl get pod prometheus-k8s-0 -n monitoring -o yaml
......
    volumeMounts:
    - mountPath: /etc/prometheus/config_out
      name: config-out
      readOnly: true
    - mountPath: /prometheus
      name: prometheus-k8s-db
......
  volumes:
......
  - name: prometheus-k8s-db
    persistentVolumeClaim:
      claimName: prometheus-k8s-db-prometheus-k8s-0
......