Prometheus 中 alertmanager报警规则详解

这篇文章介绍prometheus和alertmanager的报警和通知规则,prometheus的配置文件名为prometheus.yml,alertmanager的配置文件名为alertmanager.yml

报警:指prometheus将监测到的异常事件发送给alertmanager,而不是指发送邮件通知
通知:指alertmanager发送异常事件的通知(邮件、webhook等)

Gmail error: starttls failed: x509: certificate signed by unknown authority

报警规则

在prometheus.yml中指定匹配报警规则的间隔

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

在prometheus.yml中指定规则文件(可使用通配符,如rules/*.rules)

# Load rules once and periodically evaluate them according to the global 'evaluation_interval'.
rule_files:
 - "/etc/prometheus/alert.rules"

并基于以下模板:

ALERT <alert name>
  IF <expression>
  [ FOR <duration> ]
  [ LABELS <label set> ]
  [ ANNOTATIONS <label set> ]

其中:

Alert name是警报标识符。它不需要是唯一的。

Expression是为了触发警报而被评估的条件。它通常使用现有指标作为/metrics端点返回的指标。

Duration是规则必须有效的时间段。例如,5s表示5秒。

Label set是将在消息模板中使用的一组标签。

在prometheus-k8s-statefulset.yaml 文件创建ruleSelector,标记报警规则角色。在prometheus-k8s-rules.yaml 报警规则文件中引用

  ruleSelector:
    matchLabels:
      role: prometheus-rulefiles
      prometheus: k8s

在prometheus-k8s-rules.yaml 使用configmap 方式引用prometheus-rulefiles

apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-k8s-rules
  namespace: monitoring
  labels:
    role: prometheus-rulefiles
    prometheus: k8s
data:
  pod.rules.yaml: |+
    groups:
    - name: noah_pod.rules
      rules:
      - alert: Pod_all_cpu_usage
        expr: (sum by(name)(rate(container_cpu_usage_seconds_total{image!=""}[5m]))*100) > 10
        for: 5m
        labels:
          severity: critical
          service: pods
        annotations:
          description: 容器 {{ $labels.name }} CPU 资源利用率大于 75% , (current value is {{ $value }})
          summary: Dev CPU 负载告警
      - alert: Pod_all_memory_usage
        expr: sort_desc(avg by(name)(irate(container_memory_usage_bytes{name!=""}[5m]))*100) > 1024*10^3*2
        for: 10m
        labels:
          severity: critical
        annotations:
          description: 容器 {{ $labels.name }} Memory 资源利用率大于 2G , (current value is {{ $value }})
          summary: Dev Memory 负载告警
      - alert: Pod_all_network_receive_usage
        expr: sum by (name)(irate(container_network_receive_bytes_total{container_name="POD"}[1m])) > 1024*1024*50
        for: 10m
        labels:
          severity: critical
        annotations:
          description: 容器 {{ $labels.name }} network_receive 资源利用率大于 50M , (current value is {{ $value }})
          summary: network_receive 负载告警

配置文件设置好后,prometheus-opeartor自动重新读取配置。
如果二次修改comfigmap 内容只需要apply

kubectl apply -f prometheus-k8s-rules.yaml

将邮件通知与rules对比一下(还需要配置alertmanager.yml才能收到邮件)

报警聚合功能

通知规则

设置alertmanager.yml的的route与receivers

global:
  # ResolveTimeout is the time after which an alert is declared resolved
  # if it has not been updated.
  resolve_timeout: 5m

  # The smarthost and SMTP sender used for mail notifications.
  smtp_smarthost: 'xxxxx'
  smtp_from: 'xxxxxxx'
  smtp_auth_username: 'xxxxx'
  smtp_auth_password: 'xxxxxx'
  # The API URL to use for Slack notifications.
  slack_api_url: 'https://hooks.slack.com/services/some/api/token'

# # The directory from which notification templates are read.
templates:
- '*.tmpl'

# The root route on which each incoming alert enters.
route:

  # The labels by which incoming alerts are grouped together. For example,
  # multiple alerts coming in for cluster=A and alertname=LatencyHigh would
  # be batched into a single group.

  group_by: ['alertname', 'cluster', 'service']

  # When a new group of alerts is created by an incoming alert, wait at
  # least 'group_wait' to send the initial notification.
  # This way ensures that you get multiple alerts for the same group that start
  # firing shortly after another are batched together on the first
  # notification.

  group_wait: 30s

  # When the first notification was sent, wait 'group_interval' to send a batch
  # of new alerts that started firing for that group.

  group_interval: 5m

  # If an alert has successfully been sent, wait 'repeat_interval' to
  # resend them.

  #repeat_interval: 1m
  repeat_interval: 15m

  # A default receiver

  # If an alert isn't caught by a route, send it to default.
  receiver: default

  # All the above attributes are inherited by all child routes and can
  # overwritten on each.

  # The child route trees.
  routes:
  - match:
      severity: critical
    receiver: email_alert

receivers:
- name: 'default'
  email_configs:
  - to : 'yi.hu@dianrong.com'
    send_resolved: true

- name: 'email_alert'
  email_configs:
  - to : 'yi.hu@dianrong.com'
    send_resolved: true

名词解释

Route

route属性用来设置报警的分发策略,它是一个树状结构,按照深度优先从左向右的顺序进行匹配。

// Match does a depth-first left-to-right search through the route tree
// and returns the matching routing nodes.
func (r *Route) Match(lset model.LabelSet) []*Route {

Alert

Alert是alertmanager接收到的报警,类型如下。

// Alert is a generic representation of an alert in the Prometheus eco-system.
type Alert struct {
    // Label value pairs for purpose of aggregation, matching, and disposition
    // dispatching. This must minimally include an "alertname" label.
    Labels LabelSet `json:"labels"`

    // Extra key/value information which does not define alert identity.
    Annotations LabelSet `json:"annotations"`

    // The known time range for this alert. Both ends are optional.
    StartsAt     time.Time `json:"startsAt,omitempty"`
    EndsAt       time.Time `json:"endsAt,omitempty"`
    GeneratorURL string    `json:"generatorURL"`
}

具有相同Lables的Alert(key和value都相同)才会被认为是同一种。在prometheus rules文件配置的一条规则可能会产生多种报警

Group

alertmanager会根据group_by配置将Alert分组。如下规则,当go_goroutines等于4时会收到三条报警,alertmanager会将这三条报警分成两组向receivers发出通知。

ALERT test1
  IF go_goroutines > 1
  LABELS {label1="l1", label2="l2", status="test"}
ALERT test2
  IF go_goroutines > 2
  LABELS {label1="l2", label2="l2", status="test"}
ALERT test3
  IF go_goroutines > 3
  LABELS {label1="l2", label2="l1", status="test"}

主要处理流程

  1. 接收到Alert,根据labels判断属于哪些Route(可存在多个Route,一个Route有多个Group,一个Group有多个Alert)
  2. 将Alert分配到Group中,没有则新建Group
  3. 新的Group等待group_wait指定的时间(等待时可能收到同一Group的Alert),根据resolve_timeout判断Alert是否解决,然后发送通知
  4. 已有的Group等待group_interval指定的时间,判断Alert是否解决,当上次发送通知到现在的间隔大于repeat_interval或者Group有更新时会发送通知

Alertmanager

Alertmanager是警报的缓冲区,它具有以下特征:

可以通过特定端点(不是特定于Prometheus)接收警报。

可以将警报重定向到接收者,如hipchat、邮件或其他人。

足够智能,可以确定已经发送了类似的通知。所以,如果出现问题,你不会被成千上万的电子邮件淹没。

Alertmanager客户端(在这种情况下是Prometheus)首先发送POST消息,并将所有要处理的警报发送到/ api / v1 / alerts。例如:

[
 {
  "labels": {
     "alertname": "low_connected_users",
     "severity": "warning"
   },
   "annotations": {
      "description": "Instance play-app:9000 under lower load",
      "summary": "play-app:9000 of job playframework-app is under lower load"
    }
 }]

alert工作流程

一旦这些警报存储在Alertmanager,它们可能处于以下任何状态:

alert 报警流程

  • Inactive:这里什么都没有发生。
  • Pending:客户端告诉我们这个警报必须被触发。然而,警报可以被分组、压抑/抑制或者静默/静音。一旦所有的验证都通过了,我们就转到Firing。
  • Firing:警报发送到Notification Pipeline,它将联系警报的所有接收者。然后客户端告诉我们警报解除,所以转换到状Inactive状态。

Prometheus有一个专门的端点,允许我们列出所有的警报,并遵循状态转换。Prometheus所示的每个状态以及导致过渡的条件如下所示:

规则不符合。警报没有激活。

规则符合。警报现在处于活动状态。 执行一些验证是为了避免淹没接收器的消息。

警报发送到接收者

Inhibition

抑制是指当警报发出后,停止重复发送由此警报引发其他错误的警报的机制。

例如,当警报被触发,通知整个集群不可达,可以配置Alertmanager忽略由该警报触发而产生的所有其他警报,这可以防止通知数百或数千与此问题不相关的其他警报。
抑制机制可以通过Alertmanager的配置文件来配置。

Inhibition允许在其他警报处于触发状态时,抑制一些警报的通知。例如,如果同一警报(基于警报名称)已经非常紧急,那么我们可以配置一个抑制来使任何警告级别的通知静音。 alertmanager.yml文件的相关部分如下所示:

inhibit_rules:- source_match:
    severity: 'critical'
  target_match:
    severity: 'warning'
  equal: ['low_connected_users']

配置抑制规则,是存在另一组匹配器匹配的情况下,静音其他被引发警报的规则。这两个警报,必须有一组相同的标签。

# Matchers that have to be fulfilled in the alerts to be muted.
target_match:
  [ <labelname>: <labelvalue>, ... ]
target_match_re:
  [ <labelname>: <regex>, ... ]

# Matchers for which one or more alerts have to exist for the
# inhibition to take effect.
source_match:
  [ <labelname>: <labelvalue>, ... ]
source_match_re:
  [ <labelname>: <regex>, ... ]

# Labels that must have an equal value in the source and target
# alert for the inhibition to take effect.
[ equal: '[' <labelname>, ... ']' ]

Silences

Silences是快速地使警报暂时静音的一种方法。 我们直接通过Alertmanager管理控制台中的专用页面来配置它们。在尝试解决严重的生产问题时,这对避免收到垃圾邮件很有用。


alertmanager 参考资料
抑制规则 inhibit_rule参考资料

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