Prometheus是一个集数据收集存储、数据查询和数据图表显示于一身的开源监控组件。本文主要讲解如何搭建Prometheus，并使用它监控Kubernetes集群。

准备工作

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1. Kubernetes集群，如果你还没有搭建好Kubernetes集群，可以参考这篇文章－Kubernetes-离线部署Kubernetes 1.9.0
2. Prometheus的docker镜像，截至笔者写这篇文章之时，最新的版本是2.3.2，如果你的Kubernetes集群不能访问Docker Hub，请将镜像pull下来放到自己的私有镜像仓库。

部署Prometheus

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1. 创建命名空间

新建一个yaml文件命名为monitor-namespace.yaml，写入如下内容

apiVersion: v1
kind: Namespace
metadata:
  name: monitoring

执行如下命令创建monitoring命名空间

kubectl create -f monitor-namespace.yaml

1. 创建ClusterRole

  你需要对上面创建的命名空间分配集群的读取权限，以便Prometheus可以通过Kubernetes的API获取集群的资源指标。
新建一个yaml文件命名为cluster-role.yaml，写入如下内容：

apiVersion: rbac.authorization.k8s.io/v1beta1
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: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: prometheus
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: prometheus
subjects:
- kind: ServiceAccount
  name: default
  namespace: monitoring

执行如下命令创建

kubectl create -f cluster-role.yaml

1. 创建Config Map

  我们需要创建一个Config Map保存后面创建Prometheus容器用到的一些配置，这些配置包含了从Kubernetes集群中动态发现pods和运行中的服务。
新建一个yaml文件命名为config-map.yaml，写入如下内容：

apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-server-conf
  labels:
    name: prometheus-server-conf
  namespace: monitoring
data:
  prometheus.yml: |-
    global:
      scrape_interval: 5s
      evaluation_interval: 5s
    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'
        scheme: https
        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_(.+)
        - 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-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-cadvisor'
        scheme: https
        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_(.+)
        - 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

执行如下命令进行创建

kubectl create -f config-map.yaml -n monitoring

1. 创建Deployment模式的Prometheus

新建一个yaml文件命名为prometheus-deployment.yaml，写入如下内容，镜像那里注意一下，我写的是我私有仓库的路径，如果kubernetes集群能访问Docker Hub请修改为【prom/prometheus:v2.3.2】：

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: prometheus-deployment
  namespace: monitoring
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: prometheus-server
    spec:
      containers:
        - name: prometheus
          image: registry.docker.uih/library/prometheus:2.3.2
          args:
            - "--config.file=/etc/prometheus/prometheus.yml"
            - "--storage.tsdb.path=/prometheus/"
          ports:
            - containerPort: 9090
          volumeMounts:
            - name: prometheus-config-volume
              mountPath: /etc/prometheus/
            - name: prometheus-storage-volume
              mountPath: /prometheus/
      volumes:
        - name: prometheus-config-volume
          configMap:
            defaultMode: 420
            name: prometheus-server-conf  
        - name: prometheus-storage-volume
          emptyDir: {}

使用如下命令部署

kubectl create -f prometheus-deployment.yaml --namespace=monitoring

部署完成后通过dashboard能够看到如下的界面：

连接Prometheus

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这里有两种方式

1. 通过kubectl命令进行端口代理
2. 针对Prometheus的POD暴露一个服务，推荐此种方式
   首先新建一个yaml文件命名为prometheus-service.yaml，写入如下内容：

apiVersion: v1
kind: Service
metadata:
  name: prometheus-service
spec:
  selector: 
    app: prometheus-server
  type: NodePort
  ports:
    - port: 9090
      targetPort: 9090 
      nodePort: 30909

执行如下命令创建服务

kubectl create -f prometheus-service.yaml --namespace=monitoring

通过dashboard可以查看到部署成功的服务

现在可以通过浏览器访问【http://10.3.14.193:30909】，看到如下界面

现在可以点击 status –> Targets，马上就可以看到所有Kubernetes集群上的Endpoint通过服务发现的方式自动连接到了Prometheus。

我们还可以通过图形化界面查看内存