前言

前面几篇文章介绍了k8s的部署、对外服务、集群网络、微服务支持，在生产环境中使用，离不开运行状态监控，本篇开始部署使用prometheus，被各大公司广泛使用的容器监控工具。

工作方式

Prometheus工作示意图：

在k8s中，关于集群的资源有metrics度量值的概念，有各种不同的exporter可以通过api接口对外提供各种度量值的及时数据，prometheus在与k8s融合工作的过程，就是通过与这些提供metric值得exporter进行交互，获取数据，整合数据，展示数据，触发告警的过程。 一、获取metrics： 1.对短暂生命周期的任务，采取拉的形式获取metrics (不常见) 2.对于exporter提供的metrics，采取拉的方式获取metrics(通常方式),对接的exporter常见的有：kube-apiserver 、cadvisor、node-exporter，也可根据应用类型部署相应的exporter，获取该应用的状态信息，目前支持的应用有：nginx/haproxy/mysql/redis/memcache等。

二、数据汇总及按需获取： 可以按照官方定义的expr表达式格式，以及PromQL语法对相应的指标进程过滤，数据展示及图形展示。不过自带的webui较为简陋，但prometheus同时提供获取数据的api，grafana可通过api获取prometheus数据源，来绘制更精细的图形效果用以展示。

expr书写格式及语法参考官方文档： https://prometheus.io/docs/prometheus/latest/querying/basics/

三、告警推送 prometheus支持多种告警媒介，对满足条件的告警自动触发告警，并可对告警的发送规则进行定制，例如重复间隔、路由等，可以实现非常灵活的告警触发。

部署

1.配置configmap，在部署前将Prometheus主程序配置文件准备好，以configmap的形式挂载进deployment中。 prometheus-configmap.yaml:

apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-config
  namespace: kube-system
data:
  prometheus.yml: |
    global:
      scrape_interval:     15s
      evaluation_interval: 15s
    rule_files:
    - /etc/prometheus/rules.yml
    alerting:
      alertmanagers:
        - static_configs:
          - targets: ["alertmanager:9093"]
    scrape_configs:

    - 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

    - 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

    - job_name: 'kubernetes-services'
      kubernetes_sd_configs:
      - role: service
      metrics_path: /probe
      params:
        module: [http_2xx]
      relabel_configs:
      - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_probe]
        action: keep
        regex: true
      - source_labels: [__address__]
        target_label: __param_target
      - target_label: __address__
        replacement: blackbox-exporter.example.com:9115
      - source_labels: [__param_target]
        target_label: instance
      - action: labelmap
        regex: __meta_kubernetes_service_label_(.+)
      - source_labels: [__meta_kubernetes_namespace]
        target_label: kubernetes_namespace
      - source_labels: [__meta_kubernetes_service_name]
        target_label: kubernetes_name

    - job_name: 'kubernetes-ingresses'
      kubernetes_sd_configs:
      - role: ingress
      relabel_configs:
      - source_labels: [__meta_kubernetes_ingress_annotation_prometheus_io_probe]
        action: keep
        regex: true
        regex: (.+)
      - source_labels: [__address__, __meta_kubernetes_pod_annotation_prometheus_io_port]
        action: replace
        regex: ([^:]+)(?::\d+)?;(\d+)
        replacement: $1:$2
        target_label: __address__
      - action: labelmap
        regex: __meta_kubernetes_pod_label_(.+)
      - source_labels: [__meta_kubernetes_namespace]
        action: replace
        target_label: kubernetes_namespace
      - source_labels: [__meta_kubernetes_pod_name]
        action: replace
        target_label: kubernetes_pod_name
    - job_name: 'kubernetes-node-exporter'
      scheme: http
      tls_config:
        ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
      bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
      kubernetes_sd_configs:
      - role: node
      relabel_configs:
      - action: labelmap
        regex: __meta_kubernetes_node_label_(.+)
      - source_labels: [__meta_kubernetes_role]
        action: replace
        target_label: kubernetes_role
      - source_labels: [__address__]
        regex: '(.*):10250'
        replacement: '${1}:31672'
        target_label: __address__

2.部署prometheus工作主程序，注意挂载上面的configmap： prometheus.deploy.yml:

apiVersion: apps/v1beta2
kind: Deployment
metadata:
  labels:
    name: prometheus-deployment
  name: prometheus
  namespace: kube-system
spec:
  replicas: 1
  selector:
    matchLabels:
      app: prometheus
  template:
    metadata:
      labels:
        app: prometheus
    spec:
      containers:
      - image: prom/prometheus:v2.0.0
        name: prometheus
        command:
        - "/bin/prometheus"
        args:
        - "--config.file=/etc/prometheus/prometheus.yml"
        - "--storage.tsdb.path=/prometheus"
        - "--storage.tsdb.retention=24h"
        ports:
        - containerPort: 9090
          protocol: TCP
        volumeMounts:
        - mountPath: "/prometheus"
          name: data
        - mountPath: "/etc/prometheus"
          name: config-volume
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
          limits:
            cpu: 500m
            memory: 2500Mi
      serviceAccountName: prometheus    
      volumes:
      - name: data
        emptyDir: {}
      - name: config-volume
        configMap:
          name: prometheus-config

3.部署svc、ingress、rbac授权。 注意：在本地是使用traefik做对外服务代理的，因此修改了默认的NodePort的svc.type为ClusterIP的方式，添加ingress后，可以以域名方式直接访问。若不做代理，可以无需部署ingress，svc.type使用默认的NodePort。 prometheus.svc.yaml:

kind: Service
apiVersion: v1
metadata:
  labels:
    app: prometheus
  name: prometheus
  namespace: kube-system
spec:
  type: ClusterIP
  ports:
  - port: 80
    protocol: TCP
    targetPort: 9090
  selector:
    app: prometheus

prometheus.ing.yaml：

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: prometheus
  namespace: kube-system
  selfLink: /apis/extensions/v1beta1/namespaces/default/ingresses/prometheus
spec:
  rules:
  - host: prometheusv19.abc.com
    http:
      paths:
      - backend:
          serviceName: prometheus
          servicePort: 80
        path: /

rbac-setup.yaml：

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

依次部署上方几个yaml文件，待初始化完成后，配置好dns记录，即可打开浏览器访问： 随便选取一个metric，点击execute，查看是否能正常获取结果输出。点击status---target，可以看到metrics的数据来源，即各exporter，点击相应exporter上的链接可查看这个exporter提供的metrics明细。

为了更好的展示图形效果，需要部署grafana，因此前已经部署有grafana，这里不再部署，贴一个all-in-one.yaml部署文件。 grafana-all-in-one.yaml:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: grafana-core
  namespace: kube-system
  labels:
    app: grafana
    component: core
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: grafana
        component: core
    spec:
      containers:
      - image: grafana/grafana:4.2.0
        name: grafana-core
        imagePullPolicy: IfNotPresent
        # env:
        resources:
          # keep request = limit to keep this container in guaranteed class
          limits:
            cpu: 100m
            memory: 100Mi
          requests:
            cpu: 100m
            memory: 100Mi
        env:
          # The following env variables set up basic auth twith the default admin user and admin password.
          - name: GF_AUTH_BASIC_ENABLED
            value: "true"
          - name: GF_AUTH_ANONYMOUS_ENABLED
            value: "false"
          # - name: GF_AUTH_ANONYMOUS_ORG_ROLE
          #   value: Admin
          # does not really work, because of template variables in exported dashboards:
          # - name: GF_DASHBOARDS_JSON_ENABLED
          #   value: "true"
        readinessProbe:
          httpGet:
            path: /login
            port: 3000
          # initialDelaySeconds: 30
          # timeoutSeconds: 1
        volumeMounts:
        - name: grafana-persistent-storage
          mountPath: /var
      volumes:
      - name: grafana-persistent-storage
        emptyDir: {}

---
apiVersion: v1
kind: Service
metadata:
  name: grafana
  namespace: kube-system
  labels:
    app: grafana
    component: core
spec:
  type: NodePort
  ports:
    - port: 3000
  selector:
    app: grafana
    component: core

访问grafana，添加prometheus数据源： 默认管理账号密码为admin admin 选择资源类型，填入prometheus的服务地址及端口号，点击保存

导入展示模板： 点击dashboard，点击import dashboard，在弹出框内填写数字315，会自动加载官方提供的315号模板，然后选择数据源为刚添加的数据源，模板就创建好了，非常easy。

基本部署到这里就结束了，下篇介绍一下prometheus的告警相关规则。

===========================================================================================

7.19更新：

最近发现，采用daemon-set方式部署的node-exporterc采集到的度量值不准确，最后发现需要将host的/proc和/sys目录挂载进node-exporter的容器内。 更新后的node-exporter.yaml文件：

apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  name: node-exporter
  namespace: default
  labels:
    k8s-app: node-exporter
spec:
  template:
    metadata:
      labels:
        k8s-app: node-exporter
    spec:
      containers:
      - image: prom/node-exporter
        name: node-exporter
        ports:
        - containerPort: 9100
          protocol: TCP
          name: http
          hostPort: 9101
        volumeMounts:
        - mountPath: /host/proc
          name: proc
        - mountPath: /host/sys
          name: sys
        args:
        - --path.procfs=/host/proc
        - --path.sysfs=/host/sys
        - --collector.filesystem.ignored-mount-points
        - "^/(dev|proc|sys|host|etc|rootfs|docker)($|/)"
      volumes:
      - hostPath:
          path: /proc
        name: proc
      - hostPath:
          path: /sys
        name: sys
---
apiVersion: v1
kind: Service
metadata:
  labels:
    k8s-app: node-exporter
  name: node-exporter
  namespace: default
spec:
  ports:
  - name: http
    port: 9100
    nodePort: 31672
    protocol: TCP
  type````````````

NodePort selector: k8s-app: node-exporter

但是发现，部署完成之后，采集到的node指标依然不准确，非常奇怪，尝试脱离k8s使用docker方式直接部署，结果采集到的node数值就很准确了，有点不明白原因，后续继续排查一下。

docker运行命令：

docker run -d \ -p 9100:9100 \ --name node-exporter \ -v "/proc:/host/proc" \ -v "/sys:/host/sys" \ -v "/:/rootfs" \ --net="host" \ prom/node-exporter:v0.14.0 \ -collector.procfs /host/proc \ -collector.sysfs /host/sys \ -collector.filesystem.ignored-mount-points "^/(sys|proc|dev|host|etc)($|/)" ```

最后，记得修改configmap内的job相关targets配置。

为什么依附于k8s集群内采集的node指标就不准确，这个问题后续得好好研究，这次先到这里。