高可用prometheus监控集群搭建(一)

高可用prometheus监控集群部署 - This article is part of a series.

Part 1: This Article

简介
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Prometheus是一个开源的监控系统，通过抓取或拉取应用程序中暴露的时间序列数据来工作。时间序列数据通常由应用程序本身通过客户端库或者成为exporter的代理来作为HTTP端点暴露。目前已经存在很多exporter和客户端库，支持多种编程语言、框架和开源应用程序。

官方架构图
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Prometheus通过配置target，来抓取对应主机、进程、服务或应用程序的指标。一组具有相同角色的target被称为job。比如，定义kubernetes-nodes的job，来抓取集群所有主机的相关指标
服务发现（target）
- 静态资源列表
- 基于文件的发现，可使用自动化配置管理工具自动更新
- 自动发现，支持基于AWS/Consul/dns/kubernetes/marathon等的服务发现
Prometheus将收集时间序列数据存储在本地，也可以配置remote_write存储到其它时间序列数据库，比如OpenTSDB、InfluxDB、M3DB等
可视化: Prometheus内置了web UI，也可以和功能强大的开源仪表板Grafana集成，可自定义dashboard满足各种定制化需求
聚合和告警: Prometheus可以查询和聚合时间序列数据，并创建规则来记录常用的查询和聚合。还可以定义警报规则，满足条件时触发警报，并推送到Alertmanager服务。Alertmanagr支持高可用的集群部署，负责管理、整合和分发警报到不通目的地，并能做到告警收敛

数据模型
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Prometheus使用一个多维时间序列数据模型，结合了时间序列名称和称为标签(label)的键/值对，这些标签提供了维度。每个时间序列由时间序列名称和标签的组合唯一标识。 <time series name> {<label name>=<label value>,...}

machine_cpu_cores{beta_kubernetes_io_arch=“amd64”,beta_kubernetes_io_os=“linux”,instance=“192.168.1.51”,job=“kubernetes-cadvisor”,kubernetes_io_arch=“amd64”,kubernetes_io_hostname=“192.168.1.51”,kubernetes_io_os=“linux”} 2 machine_cpu_cores收集的是主机的cpu核数，taget label标识了是job kubernetes-cadvisor抓取的，instance 192.168.1.51的指标，还包括此node的其它labels；获取到的value值为2

集群拓扑图
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节点部署规划
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IP	k8srole	service
192.168.1.50	master	node-exporter/alertmanager
192.168.1.51	node	node-exporter/alertmanager/grafana/prometheus-0/prometheus-federate-0/kube-state-metrics
192.168.1.52	node	node-exporter/alertmanager/prometheus-1/prometheus-federate-1

部署架构图
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在多k8s集群模式下，每个集群部署prometheus server用于收集该集群相关指标,借助prometheus联邦模式，实现监控数据的统一收集展现及告警通知

集群内prometheus server部署
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statefulset方式部署,并使用本地持久卷 Local Volume

创建prometheus server数据目录
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$ groupadd -g 65534 nfsnobody
$ useradd -g 65534 -u 65534 -s /sbin/nologin  nfsnobody
$ chown nfsnobody. /data/prometheus/

创建storageclass,指定卷挂载为拓扑感知模式，即pod调度后再绑定卷
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$cat storageclass.yaml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: prometheus-lpv
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer

创建两个local volume，利用nodeAffinity绑定到指定节点
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# cat pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: prometheus-lpv-0
spec:
  capacity:
    storage: 50Gi
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: prometheus-lpv
  local:
    path: /data/prometheus
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - 192.168.1.51
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: prometheus-lpv-1
spec:
  capacity:
    storage: 50Gi
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: prometheus-lpv
  local:
    path: /data/prometheus
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - 192.168.1.52

初始化rabc
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$cat rbac-setup.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: prometheus
rules:
- apiGroups: [""]
  resources:
  - nodes
  - nodes/proxy
  - services
  - endpoints
  - pods
  verbs: ["get", "list", "watch"]
- apiGroups:
  - extensions
  resources:
  - ingresses
  verbs: ["get", "list", "watch"]
- nonResourceURLs: ["/metrics"]
  verbs: ["get"]
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: prometheus
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: prometheus
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: prometheus
subjects:
- kind: ServiceAccount
  name: prometheus
  namespace: kube-system

######　创建configmap(prometheus.yml)

$cat prometheus-configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-config
  namespace: kube-system
data:
  prometheus.yml: |
    global:
      scrape_interval:     30s
      evaluation_interval: 30s
      external_labels:
        cluster: "01"
    scrape_configs:
    - job_name: 'prometheus'
      static_configs:
        - targets:
            - prometheus-0.prometheus:9090
            - prometheus-1.prometheus:9090
    - job_name: 'kubernetes-apiservers'
      kubernetes_sd_configs:
      - role: endpoints
      scheme: https
      tls_config:
        ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
      bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
      relabel_configs:
      - source_labels: [__meta_kubernetes_namespace, __meta_kubernetes_service_name, __meta_kubernetes_endpoint_port_name]
        action: keep
        regex: default;kubernetes;https
    - job_name: 'kubernetes-nodes'
      kubernetes_sd_configs:
      - role: node
      scheme: https
      tls_config:
        ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
      bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
      relabel_configs:
      - action: labelmap
        regex: __meta_kubernetes_node_label_(.+)
      - target_label: __address__
        replacement: kubernetes.default.svc:443
      - source_labels: [__meta_kubernetes_node_name]
        regex: (.+)
        target_label: __metrics_path__
        replacement: /api/v1/nodes/${1}/proxy/metrics
    - job_name: 'kubernetes-cadvisor'
      kubernetes_sd_configs:
      - role: node
      scheme: https
      tls_config:
        ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
      bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
      relabel_configs:
      - action: labelmap
        regex: __meta_kubernetes_node_label_(.+)
      - target_label: __address__
        replacement: kubernetes.default.svc:443
      - source_labels: [__meta_kubernetes_node_name]
        regex: (.+)
        target_label: __metrics_path__
        replacement: /api/v1/nodes/${1}/proxy/metrics/cadvisor
      metric_relabel_configs:
      - action: replace
        source_labels: [id]
        regex: '^/machine\.slice/machine-rkt\\x2d([^\\]+)\\.+/([^/]+)\.service$'
        target_label: rkt_container_name
        replacement: '${2}-${1}'
      - action: replace
        source_labels: [id]
        regex: '^/system\.slice/(.+)\.service$'
        target_label: systemd_service_name
        replacement: '${1}'
    - job_name: 'kubernetes-pods'
      kubernetes_sd_configs:
      - role: pod
      relabel_configs:
      - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_scrape]
        action: keep
        regex: true
      - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_path]
        action: replace
        target_label: __metrics_path__
        regex: (.+)
      - source_labels: [__address__, __meta_kubernetes_pod_annotation_prometheus_io_port]
        action: replace
        regex: ([^:]+)(?::\d+)?;(\d+)
        replacement: $1:$2
        target_label: __address__
      - action: labelmap
        regex: __meta_kubernetes_pod_label_(.+)
      - source_labels: [__meta_kubernetes_namespace]
        action: replace
        target_label: kubernetes_namespace
      - source_labels: [__meta_kubernetes_pod_name]
        action: replace
        target_label: kubernetes_pod_name
    - 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
      - source_labels: [__address__]
        action: replace
        target_label: instance
        regex: (.+):(.+)
        replacement: $1

statefulset创建后，pod的命名方式为<statefulset name>-0、<statefulset name>-1… 对应生成的dns域名为，podname.stateflusetname.namespace.svc.cluster.local

jobprometheus用来获取prometheus本身的监控指标，本例中prometheus server为statefulset方式部署，指定targets为prometheus-0.prometheus:9090、prometheus-1.prometheus:9090 external_labels用于外部系统标签，在使用remote_write或者federate时，可以为该集群指标添加标签

创建headless service
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$cat service-statefulset.yaml
apiVersion: v1
kind: Service
metadata:
  name: prometheus
  namespace: kube-system
spec:
  ports:
    - name: prometheus
      port: 9090
      targetPort: 9090
  selector:
    k8s-app: prometheus
  clusterIP: None

创建prometheus statefulset
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$cat prometheus-statefulset.yaml
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: prometheus
  namespace: kube-system
  labels:
    k8s-app: prometheus
    kubernetes.io/cluster-service: "true"
spec:
  serviceName: "prometheus"
  podManagementPolicy: "Parallel"
  replicas: 2
  selector:
    matchLabels:
      k8s-app: prometheus
  template:
    metadata:
      labels:
        k8s-app: prometheus
      annotations:
        scheduler.alpha.kubernetes.io/critical-pod: ''
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - key: k8s-app
                operator: In
                values:
                - prometheus
            topologyKey: "kubernetes.io/hostname"
      priorityClassName: system-cluster-critical
      hostNetwork: true
      dnsPolicy: ClusterFirstWithHostNet
      containers:
      - name: prometheus-server-configmap-reload
        image: "jimmidyson/configmap-reload:v0.1"
        imagePullPolicy: "IfNotPresent"
        args:
          - --volume-dir=/etc/config
          - --webhook-url=http://localhost:9090/-/reload
        volumeMounts:
          - name: config-volume
            mountPath: /etc/config
            readOnly: true
        resources:
          limits:
            cpu: 10m
            memory: 10Mi
          requests:
            cpu: 10m
            memory: 10Mi
      - image: prom/prometheus:v2.11.0
        imagePullPolicy: IfNotPresent
        name: prometheus
        command:
          - "/bin/prometheus"
        args:
          - "--config.file=/etc/prometheus/prometheus.yml"
          - "--storage.tsdb.path=/prometheus"
          - "--storage.tsdb.retention=24h"
          - "--web.console.libraries=/etc/prometheus/console_libraries"
          - "--web.console.templates=/etc/prometheus/consoles"
          - "--web.enable-lifecycle"
        ports:
          - containerPort: 9090
            protocol: TCP
        volumeMounts:
          - mountPath: "/prometheus"
            name: prometheus-data
          - mountPath: "/etc/prometheus"
            name: config-volume
        readinessProbe:
          httpGet:
            path: /-/ready
            port: 9090
          initialDelaySeconds: 30
          timeoutSeconds: 30
        livenessProbe:
          httpGet:
            path: /-/healthy
            port: 9090
          initialDelaySeconds: 30
          timeoutSeconds: 30
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
          limits:
            cpu: 1000m
            memory: 2500Mi
      serviceAccountName: prometheus
      volumes:
        - name: config-volume
          configMap:
            name: prometheus-config
  volumeClaimTemplates:
    - metadata:
        name: prometheus-data
      spec:
        accessModes: [ "ReadWriteOnce" ]
        storageClassName: "prometheus-lpv"
        resources:
          requests:
            storage: 20Gi

volumeClaimTemplates指定storageclass,在pod创建时会生成PVC，为pod分配prometheus-lpv的pv。只要PVC不被删除，pod均会被调度到已绑定的pv节点上。

$ kubectl get pv
prometheus-lpv-0    50Gi       RWO            Retain           Bound    kube-system/prometheus-data-prometheus-1       prometheus-lpv            13d
prometheus-lpv-1    50Gi       RWO            Retain           Bound    kube-system/prometheus-data-prometheus-0       prometheus-lpv            13d
$ kubectl get pvc -n kube-system
prometheus-data-prometheus-0       Bound    prometheus-lpv-1    50Gi       RWO            prometheus-lpv   13d
prometheus-data-prometheus-1       Bound    prometheus-lpv-0    50Gi       RWO            prometheus-lpv   13d