Prometheus + Alertmanager

[CodeShellDev]

Use generic webhook alert type in Alertmanager

Payload

{
  "number": "mandatory",
  "recipients": "mandatory",
  "text_mode": "styled",
  "version": "4",
  "groupKey": "host:server01 severity:critical",
  "truncatedAlerts": 0,
  "status": "firing",
  "receiver": "webhook",
  "groupLabels": {
    "alertname": "HighCPUUsage",
    "host": "server01"
  },
  "commonLabels": {
    "alertname": "HighCPUUsage",
    "severity": "critical",
    "instance": "server01:9100"
  },
  "commonAnnotations": {
    "summary": "CPU usage is above 90% on server01",
    "description": "The CPU usage on host server01 has exceeded the threshold of 90% for more than 5 minutes."
  },
  "externalURL": "http://alertmanager.example.com",
  "alerts": [
    {
      "status": "firing",
      "labels": {
        "alertname": "HighCPUUsage",
        "severity": "critical",
        "instance": "server01:9100"
      },
      "annotations": {
        "summary": "CPU usage is above 90% on server01",
        "description": "The CPU usage on host server01 has exceeded the threshold of 90% for more than 5 minutes."
      },
      "startsAt": "2025-09-20T14:30:00Z",
      "endsAt": "0001-01-01T00:00:00Z",
      "generatorURL": "http://prometheus.example.com/graph?g0.expr=cpu_usage%3E90",
      "fingerprint": "abcd1234ef567890"
    }
  ]
}

Config

Message Template

🚨 **AlertManager Notification** 🚨

Status: {{@status}}
Group: {{@groupLabels.alertname}}
Receiver: {{@receiver}}
{{range @alerts}}
{{- $emoji := "ℹ️" -}}
{{- if eq .labels.severity "critical" }}{{- $emoji = "🆘" -}}{{- end -}}
{{- if eq .labels.severity "warning" }}{{- $emoji = "⚠️" -}}{{- end -}}

{{$emoji}} **{{.labels.alertname}}** on {{.labels.instance}}!
{{.annotations.summary}}
Started at: {{.startsAt}}
{{if ne .endsAt "0001-01-01T00:00:00Z"}}Ended at: {{.endsAt}}{{end}}
More info: {{.generatorURL}}
{{end}}

Use text_mode: styled in body for BOLD and ITALIC:

https://sec-signal-api/v2/send?@text_mode=styled