解读Prometheus监控Kubernetes的配置文件
来源：https://segmentfault.com/a/1190000013230914
前言
Prometheus 是一个开源和社区驱动的监控&报警&时序数据库的项目。来源于谷歌BorgMon项目。现在最常见的Kubernetes容器管理系统中，通常会搭配Prometheus进行监控。主要监控：
Node:如主机CPU，内存，网络吞吐和带宽占用，磁盘I/O和磁盘使用等指标。node-exporter采集。
容器关键指标:集群中容器的CPU详细状况，内存详细状况，Network，FileSystem和Subcontainer等。通过cadvisor采集。
Kubernetes集群上部署的应用：监控部署在Kubernetes集群上的应用。主要是pod，service，ingress和endpoint。通过black-box和kube-apiserver的接口采集。
prometheus自身提供了一些资源的自动发现功能，下面是我从官方github上截图，罗列了目前提供的资源发现：
上图可知prometheus自身提供了自动发现kubernetes的监控目标的功能。相应，配置文件官方也提供了一份，今天我们就解读一下该配置文件。
配置文件解读
首先直接上官方的配置文件：
# A scrape configuration for running Prometheus on a Kubernetes cluster. # This uses separate scrape configs for cluster components (i.e. API server, node) # and services to allow each to use different authentication configs. # # Kubernetes labels will be added as Prometheus labels on metrics via the # `labelmap` relabeling action. # # If you are using Kubernetes 1.7.2 or earlier, please take note of the comments # for the kubernetes-cadvisor job; you will need to edit or remove this job. # Scrape config for API servers. # # Kubernetes exposes API servers as endpoints to the default/kubernetes # service so this uses `endpoints` role and uses relabelling to only keep # the endpoints associated with the default/kubernetes service using the # default named port `https`. This works for single API server deployments as # well as HA API server deployments. scrape_configs: - job_name: 'kubernetes-apiservers' kubernetes_sd_configs: - role: endpoints # Default to scraping over https. If required, just disable this or change to # `http`. scheme: https # This TLS & bearer token file config is used to connect to the actual scrape # endpoints for cluster components. This is separate to discovery auth # configuration because discovery & scraping are two separate concerns in # Prometheus. The discovery auth config is automatic if Prometheus runs inside # the cluster. Otherwise, more config options have to be provided within the # <kubernetes_sd_config>. tls_config: ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt # If your node certificates are self-signed or use a different CA to the # master CA, then disable certificate verification below. Note that # certificate verification is an integral part of a secure infrastructure # so this should only be disabled in a controlled environment. You can # disable certificate verification by uncommenting the line below. # # insecure_skip_verify: true bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token # Keep only the default/kubernetes service endpoints for the https port. This # will add targets for each API server which Kubernetes adds an endpoint to # the default/kubernetes service. relabel_configs: - source_labels: [__meta_kubernetes_namespace, __meta_kubernetes_service_name, __meta_kubernetes_endpoint_port_name] action: keep regex: default;kubernetes;https # Scrape config for nodes (kubelet). # # Rather than connecting directly to the node, the scrape is proxied though the # Kubernetes apiserver. This means it will work if Prometheus is running out of # cluster, or can't connect to nodes for some other reason (e.g. because of # firewalling). - job_name: 'kubernetes-nodes' # Default to scraping over https. If required, just disable this or change to # `http`. scheme: https # This TLS & bearer token file config is used to connect to the actual scrape # endpoints for cluster components. This is separate to discovery auth # configuration because discovery & scraping are two separate concerns in # Prometheus. The discovery auth config is automatic if Prometheus runs inside # the cluster. Otherwise, more config options have to be provided within the # <kubernetes_sd_config>. 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/${1}/proxy/metrics # Scrape config for Kubelet cAdvisor. # # This is required for Kubernetes 1.7.3 and later, where cAdvisor metrics # (those whose names begin with 'container_') have been removed from the # Kubelet metrics endpoint. This job scrapes the cAdvisor endpoint to # retrieve those metrics. # # In Kubernetes 1.7.0-1.7.2, these metrics are only exposed on the cAdvisor # HTTP endpoint; use 'replacement: /api/v1/nodes/${1}:4194/proxy/metrics' # in that case (and ensure cAdvisor's HTTP server hasn't been disabled with # the --cadvisor-port=0 Kubelet flag). # # This job is not necessary and should be removed in Kubernetes 1.6 and # earlier versions, or it will cause the metrics to be scraped twice. - job_name: 'kubernetes-cadvisor' # Default to scraping over https. If required, just disable this or change to # `http`. scheme: https # This TLS & bearer token file config is used to connect to the actual scrape # endpoints for cluster components. This is separate to discovery auth # configuration because discovery & scraping are two separate concerns in # Prometheus. The discovery auth config is automatic if Prometheus runs inside # the cluster. Otherwise, more config options have to be provided within the # <kubernetes_sd_config>. 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 # Scrape config for service endpoints. # # The relabeling allows the actual service scrape endpoint to be configured # via the following annotations: # # * `prometheus.io/scrape`: Only scrape services that have a value of `true` # * `prometheus.io/scheme`: If the metrics endpoint is secured then you will need # to set this to `https` & most likely set the `tls_config` of the scrape config. # * `prometheus.io/path`: If the metrics path is not `/metrics` override this. # * `prometheus.io/port`: If the metrics are exposed on a different port to the # service then set this appropriately. - 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 # Example scrape config for probing services via the Blackbox Exporter. # # The relabeling allows the actual service scrape endpoint to be configured # via the following annotations: # # * `prometheus.io/probe`: Only probe services that have a value of `true` - job_name: 'kubernetes-services' metrics_path: /probe params: module: [http_2xx] kubernetes_sd_configs: - role: service 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 # Example scrape config for probing ingresses via the Blackbox Exporter. # # The relabeling allows the actual ingress scrape endpoint to be configured # via the following annotations: # # * `prometheus.io/probe`: Only probe services that have a value of `true` - job_name: 'kubernetes-ingresses' metrics_path: /probe params: module: [http_2xx] kubernetes_sd_configs: - role: ingress relabel_configs: - source_labels: [__meta_kubernetes_ingress_annotation_prometheus_io_probe] action: keep regex: true - source_labels: [__meta_kubernetes_ingress_scheme,__address__,__meta_kubernetes_ingress_path] regex: (.+);(.+);(.+) replacement: ${1}://${2}${3} 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_ingress_label_(.+) - source_labels: [__meta_kubernetes_namespace] target_label: kubernetes_namespace - source_labels: [__meta_kubernetes_ingress_name] target_label: kubernetes_name # Example scrape config for pods # # The relabeling allows the actual pod scrape endpoint to be configured via the # following annotations: # # * `prometheus.io/scrape`: Only scrape pods that have a value of `true` # * `prometheus.io/path`: If the metrics path is not `/metrics` override this. # * `prometheus.io/port`: Scrape the pod on the indicated port instead of the # pod's declared ports (default is a port-free target if none are declared). - 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当然该配置文件，是在prometheus部署在k8s中生效的,即in-cluster模式。
kubernetes-apiservers
该项主要是让prometheus程序可以访问kube-apiserver，进而进行服务发现。看一下服务发现的代码可以看出，主要服务发现：node，service，ingress，pod。
switch d.role { case 'endpoints': var wg sync.WaitGroup for _, namespace := range namespaces {
elw := cache.NewListWatchFromClient(rclient, 'endpoints', namespace, nil)
slw := cache.NewListWatchFromClient(rclient, 'services', namespace, nil)
plw := cache.NewListWatchFromClient(rclient, 'pods', namespace, nil)
eps := NewEndpoints(
log.With(d.logger, 'role', 'endpoint'),
cache.NewSharedInformer(slw, &apiv1.Service{}, resyncPeriod),
cache.NewSharedInformer(elw, &apiv1.Endpoints{}, resyncPeriod),
cache.NewSharedInformer(plw, &apiv1.Pod{}, resyncPeriod),
) go eps.endpointsInf.Run(ctx.Done()) go eps.serviceInf.Run(ctx.Done()) go eps.podInf.Run(ctx.Done()) for !eps.serviceInf.HasSynced() {
time.Sleep(100 * time.Millisecond)
} for !eps.endpointsInf.HasSynced() {
time.Sleep(100 * time.Millisecond)
} for !eps.podInf.HasSynced() {
time.Sleep(100 * time.Millisecond)
}
wg.Add(1) go func() { defer wg.Done()
eps.Run(ctx, ch)
}()
}
wg.Wait() case 'pod': var wg sync.WaitGroup for _, namespace := range namespaces {
plw := cache.NewListWatchFromClient(rclient, 'pods', namespace, nil)
pod := NewPod(
log.With(d.logger, 'role', 'pod'),
cache.NewSharedInformer(plw, &apiv1.Pod{}, resyncPeriod),
) go pod.informer.Run(ctx.Done()) for !pod.informer.HasSynced() {
time.Sleep(100 * time.Millisecond)
}
wg.Add(1) go func() { defer wg.Done()
pod.Run(ctx, ch)
}()
}
wg.Wait() case 'service': var wg sync.WaitGroup for _, namespace := range namespaces {
slw := cache.NewListWatchFromClient(rclient, 'services', namespace, nil)
svc := NewService(
log.With(d.logger, 'role', 'service'),
cache.NewSharedInformer(slw, &apiv1.Service{}, resyncPeriod),
) go svc.informer.Run(ctx.Done()) for !svc.informer.HasSynced() {
time.Sleep(100 * time.Millisecond)
}
wg.Add(1) go func() { defer wg.Done()
svc.Run(ctx, ch)
}()
}
wg.Wait() case 'ingress': var wg sync.WaitGroup for _, namespace := range namespaces {
ilw := cache.NewListWatchFromClient(reclient, 'ingresses', namespace, nil)
ingress := NewIngress(
log.With(d.logger, 'role', 'ingress'),
cache.NewSharedInformer(ilw, &extensionsv1beta1.Ingress{}, resyncPeriod),
) go ingress.informer.Run(ctx.Done()) for !ingress.informer.HasSynced() {
time.Sleep(100 * time.Millisecond)
}
wg.Add(1) go func() { defer wg.Done()
ingress.Run(ctx, ch)
}()
}
wg.Wait() case 'node':
nlw := cache.NewListWatchFromClient(rclient, 'nodes', api.NamespaceAll, nil)
node := NewNode(
log.With(d.logger, 'role', 'node'),
cache.NewSharedInformer(nlw, &apiv1.Node{}, resyncPeriod),
) go node.informer.Run(ctx.Done()) for !node.informer.HasSynced() {
time.Sleep(100 * time.Millisecond)
}
node.Run(ctx, ch) default:
level.Error(d.logger).Log('msg', 'unknown Kubernetes discovery kind', 'role', d.role)
}
kubernetes-nodes
发现node以后，通过/api/v1/nodes/${1}/proxy/metrics来获取node的metrics。
kubernetes-cadvisor
cadvisor已经被集成在kubelet中，所以发现了node就相当于发现了cadvisor。通过 /api/v1/nodes/${1}/proxy/metrics/cadvisor采集容器指标。
kubernetes-services和kubernetes-ingresses
该两种资源监控方式差不多，都是需要安装black-box，然后类似于探针去定时访问，根据返回的http状态码来判定service和ingress的服务可用性。
PS：不过我自己在这里和官方的稍微有点区别，
- target_label: __address__ replacement: blackbox-exporter.example.com:9115官方大致是需要我们要创建black-box 的ingress从外部访问，这样从效率和安全性都不是最合适的。所以我一般都是直接内部dns访问。如下
- target_label: __address__ replacement: blackbox-exporter.kube-system:9115
当然看源码可以发现，并不是所有的service和ingress都会健康监测，如果需要将服务进行健康监测，那么你部署应用的yaml文件加一些注解。例如：
对于service和ingress：
需要加注解：prometheus.io/scrape: 'true'
apiVersion: v1kind: Servicemetadata: annotations: prometheus.io/scrape: 'true' name: prometheus-node-exporter namespace: kube-system labels: app: prometheus component: node-exporterspec: clusterIP: None ports: - name: prometheus-node-exporter port: 9100 protocol: TCP selector: app: prometheus component: node-exporter type: ClusterIPkubernetes-pods
对于pod的监测也是需要加注解：
prometheus.io/scrape，为true则会将pod作为监控目标。
prometheus.io/path，默认为/metrics
prometheus.io/port , 端口
所以看到此处可以看出，该job并不是监控pod的指标，pod已经通过前面的cadvisor采集。此处是对pod中应用的监控。写过exporter的人应该对这个概念非常清楚。通俗讲，就是你pod中的应用提供了prometheus的监控功能，加上对应的注解，那么该应用的metrics会定时被采集走。
kubernetes-service-endpoints
对于服务的终端节点，也需要加注解：
prometheus.io/scrape，为true则会将pod作为监控目标。
prometheus.io/path，默认为/metrics
prometheus.io/port , 端口
prometheus.io/scheme 默认http，如果为了安全设置了https，此处需要改为https
这个基本上同上的。采集service-endpoints的metrics。
个人认为：如果某些部署应用只有pod没有service，那么这种情况只能在pod上加注解，通过kubernetes-pods采集metrics。如果有service，那么就无需在pod加注解了，直接在service上加即可。毕竟service-endpoints最终也会落到pod上。
总结
配置项总结
kubernetes-service-endpoints和kubernetes-pods采集应用中metrics，当然并不是所有的都提供了metrics接口。
kubernetes-ingresses 和kubernetes-services 健康监测服务和ingress健康的状态
kubernetes-cadvisor 和 kubernetes-nodes，通过发现node，监控node 和容器的cpu等指标
自动发现源码
参考client-go和prometheus自动发现k8s，这种监听k8s集群中资源的变化，使用informer实现，不要轮询kube-apiserver接口。
参考
该配置文件需要部署一些组件来支持prometheus对k8s的监控，例如black-exporter。因为要自动发现，获取集群的一些信息，所以也要做rbac的授权。具体参考：https://github.com/giantswarm/kubernetes-prometheus
人生舞台的大幕随时都可能拉开，关键是你愿意表演，还是选择躲避。
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