Alerting rules allow you to define alert conditions based on Prometheus expression language expressions and to send notifications about firing alerts to an external service. Whenever the alert expression results in one or more vector elements at a given point in time, the alert counts as active for these elements' label sets. If you have installed Prometheus with Helm, you have a Custom Resource Definitions (CRD) called PrometheusRule. Below is an example
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apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
annotations:
meta.helm.sh/release-name: mon
meta.helm.sh/release-namespace: monitoring
labels:
app: kube-prometheus-stack
release: mon
name: regolatest
namespace: monitoring
spec:
groups:
- name: customRules
rules:
- alert: rateGraph
expr: rate(prometheus_http_requests_total{handler="/graph"}[5m]) * 60 >= 2
labels:
severity: none
annotations:
description: long descriptionThis alert is activated if, in the last 5 minutes, the http requests per minute towards the sub-path "/graph" of the Prometheus dashboard exceeds the value 2
summary: tanteMany richiesterequests ato "graph"
- alert: rateAlerts
expr: rate(prometheus_http_requests_total{handler="/alerts"}[5m]) * 60 >= 3
labels:
severity: none
annotations:
description: long description This alert is activated if, in the last 5 minutes, the http requests per minute towards the sub-path "/alerts" of the Prometheus dashboard exceeds the value 3
summary: tanteMany richiesterequests ato "alerts" |
In this example we have inserted 2 rules that evaluate the rate of http requests to Prometheus dashboard pages. We will then update these web pages via the browser, to trigger the alert. Also note the labels adopted in this manifest.