prometheus-operator使用【prometheus配置说明】

全局配置 

参考官网：https://prometheus.io/docs/prometheus/latest/configuration/configuration/#kubernetes_sd_config

global:
  # How frequently to scrape targets by default.
  [ scrape_interval:  | default = 1m ]

  # How long until a scrape request times out.
  [ scrape_timeout:  | default = 10s ]

  # How frequently to evaluate rules.
  [ evaluation_interval:  | default = 1m ]

  # The labels to add to any time series or alerts when communicating with
  # external systems (federation, remote storage, Alertmanager).
  external_labels:
    [ :  ... ]

# Rule files specifies a list of globs. Rules and alerts are read from
# all matching files.
rule_files:
  [ -  ... ]

# A list of scrape configurations.
scrape_configs:
  [ -  ... ]

# Alerting specifies settings related to the Alertmanager.
alerting:
  alert_relabel_configs:
    [ -  ... ]
  alertmanagers:
    [ -  ... ]

# Settings related to the remote write feature.
remote_write:
  [ -  ... ]

# Settings related to the remote read feature.
remote_read:
  [ -  ... ]

更改指标标签

更改标签的时机：抓取前修改、抓取后修改、告警时修改

• 采集数据之前，通过relabel_config；
• 采集数据之后，写入存储之前，通过metric_relabel_configs
• 在告警前修改标签，通过alert_relabel_configs

JOB配置 

- job_name: prometheus
  honor_labels: false
  kubernetes_sd_configs:
  - role: endpoints
    namespaces:
      names:
      - monitoring
  scrape_interval: 30s
  relabel_configs:
  - action: keep
    source_labels:
    - __meta_kubernetes_service_label_prometheus
    regex: k8s
  - source_labels:
    - __meta_kubernetes_endpoint_address_target_kind
    - __meta_kubernetes_endpoint_address_target_name
    separator: ;
    regex: Pod;(.*)
    replacement: ${1}
    target_label: pod
  - source_labels:
    - __meta_kubernetes_namespace
    target_label: namespace

• kubernetes_sd_configs：使用这个配置可以自动发现 k8s 中 node、service、pod、endpoint、ingress，并为其添加监控，更多的内容可以直接查看官方文档。__meta_kubernetes_xxxxx具体什么意思都可以在官网找到。
• endpoints:采用endpoints方式采集，每创建一个 service 就会创建一个对应的 endpoint，通过endpoint方式可以将service下所有的pod都采集到。
• 下面配置的意思是只有 service 的标签包含 prometheus=k8s，k8s 才会对其对应的 endpoint 进行采集。所以我们后面要为 Prometheus 创建一个 service，并且要为这个 service 加上 prometheus: k8s 这样的标签。

  - action: keep
    source_labels:
    - __meta_kubernetes_service_label_prometheus
    regex: k8s

• 下面配置意识是如果 __meta_kubernetes_endpoint_address_target_kind 的值为 Pod，__meta_kubernetes_endpoint_address_target_name 的值为 prometheus-0，在它们之间加上一个 ; 之后，它们合起来就是 Pod;prometheus-0。使用正则表达式 Pod;(.*) 对其进行匹配，那么 ${1} 就是取第一个分组，它值就是 prometheus-0，最后将这个值交给 pod 这个标签。因此这一段配置就是为所有采集到的监控指标增加一个 pod=prometheus-0 的标签。如果 __meta_kubernetes_endpoint_address_target_kind 的值不是 Pod，那么不会添加任何标签。

- source_labels:
    - __meta_kubernetes_endpoint_address_target_kind
    - __meta_kubernetes_endpoint_address_target_name
  separator: ;
  regex: Pod;(.*)
  replacement: ${1}
  target_label: pod

• 没有指定 url，Prometheus 会采集默认的 url /metrics。

定义告警规则

groups:
- name: example
  rules:
  - alert: HighRequestLatency
    expr: job:request_latency_seconds:mean5m{job="myjob"} > 0.5
    for: 10m
    labels:
      severity: page
    annotations:
      summary: High request latency

参考官网： https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/

for：Prometheus将在每次发出警报之前检查警报在10分钟内是否继续处于活动状态

labels：允许指定一组附加标签来附加到警报。任何现有的冲突标签都将被覆盖。标签值可以模板化。

annotations：指定了一组信息标签，可用于存储更长的附加信息，例如警报说明或运行手册链接。注释值可以模板化。

模板化

标签和注释值可以使用控制台模板进行模板化。该$labels 变量保存警报实例的标签键/值对。可以通过$externalLabels变量访问已组态的外部标签。该 $value变量保存警报实例的评估值。

# To insert a firing element's label values:
{{ $labels. }}
# To insert the numeric expression value of the firing element:
{{ $value }}

例子：

groups:
- name: example
  rules:

  # Alert for any instance that is unreachable for >5 minutes.
  - alert: InstanceDown
    expr: up == 0
    for: 5m
    labels:
      severity: page
    annotations:
      summary: "Instance {{ $labels.instance }} down"
      description: "{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes."

  # Alert for any instance that has a median request latency >1s.
  - alert: APIHighRequestLatency
    expr: api_http_request_latencies_second{quantile="0.5"} > 1
    for: 10m
    annotations:
      summary: "High request latency on {{ $labels.instance }}"
      description: "{{ $labels.instance }} has a median request latency above 1s (current value: {{ $value }}s)"