prometheus添加自定义监控与告警（etcd为例）

一、步骤及注意事项（前提，部署参考部署篇）

1. 一般etcd集群会开启HTTPS认证，因此访问etcd需要对应的证书
2. 使用证书创建etcd的secret
3. 将etcd的secret挂在到prometheus
4. 创建etcd的servicemonitor对象（匹配kube-system空间下具有k8s-app=etcd标签的service）
5. 创建service关联被监控对象

二、实际操作步骤（etcd证书默认路径：/etc/kubernetes/pki/etcd/）

1、创建etcd的secret

cd /etc/kubernetes/pki/etcd/
kubectl create secret generic etcd-certs --from-file=healthcheck-client.crt --from-file=healthcheck-client.key --from-file=ca.crt -n monitoring

2、添加secret到名为k8s的prometheus对象上（kubectl edit prometheus k8s -n monitoring或者修改yaml文件并更新资源）

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
  baseImage: quay.io/prometheus/prometheus
  nodeSelector:
    kubernetes.io/os: linux
  podMonitorNamespaceSelector: {}
  podMonitorSelector: {}
  replicas:
  secrets:
  - etcd-certs
  resources:
    requests:
      memory: 400Mi
  ruleSelector:
    matchLabels:
      prometheus: k8s
      role: alert-rules
  securityContext:
    fsGroup:
    runAsNonRoot: true
    runAsUser:
  serviceAccountName: prometheus-k8s
  serviceMonitorNamespaceSelector: {}
  serviceMonitorSelector: {}
  version: v2.11.0

3、创建servicemonitoring对象

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: etcd-k8s
  namespace: monitoring
  labels:
    k8s-app: etcd-k8s
spec:
  jobLabel: k8s-app
  endpoints:
  - port: port
    interval: 30s
    scheme: https
    tlsConfig:
      caFile: /etc/prometheus/secrets/etcd-certs/ca.crt
      certFile: /etc/prometheus/secrets/etcd-certs/healthcheck-client.crt
      keyFile: /etc/prometheus/secrets/etcd-certs/healthcheck-client.key
      insecureSkipVerify: true
  selector:
    matchLaels:
      k8s-app: etcd
  namespaceSelector:
    matchNames:
    - kube-system

4、创建service并自定义endpoint（考虑到etcd可能部署在kubernetes集群外，因此自定义endpoint）

apiVersion: v1
kind: Service
metadata:
  name: etcd-k8s
  namespace: kube-system
  labels:
    k8s-app: etcd
spec:
  type: ClusterIP
  clusterIP: None
  ports:
  - name: port
    port:
    protocol: TCP

---
apiVersion: v1
kind: Endpoints
metadata:
  name: etcd-k8s
  namespace: kube-system
  labels:
    k8s-app: etcd
subsets:
- addresses:
  - ip: 1.1.1.11
  - ip: 1.1.1.12
  - ip: 1.1.1.13

    nodeName: etcd-master
  ports:
  - name: port
    port:
    protocol: TCP

此处正常能通过prometheus的页面看到对应的监控信息了

若监控中出现报错：connection refused，修改/etc/kubernetes/manifests下的etcd.yaml文件

方法一：--listen-client-urls=https://0.0.0.0:2379

方法二：--listen-client-urls=https://127.0.0.1:2379,https://1.1.1.11:2379

三、创建自定义告警

1. 创建一个prometheusRule资源后再prometheus的pod中会生成对应的告警配置文件
2. 注意：此处的标签一定要匹配
3. 告警项：若etcd集群有一半以上的节点可用，则认为集群可用，否则产生告警

apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  labels:
    prometheus: k8s
    role: alert-rules
  name: etcd-rules
  namespace: monitoring
spec:
  groups:
  - name: etcd-exporter.rules
    rules:
    - alert: EtcdClusterUnavailable
      annotations:
        summary: etcd cluster small
        description: If one more etcd peer goes down the cluster will be unavailable
      expr: |
        count(up{job="etcd"} == ) > (count(up{job="etcd"}) / -)
      for: 3m
      labels:
        severity: critical