# Alerting

## Навигация
- [🏠 Главная страница курса](../../../README.md)
- [📚 Модуль 5](../README.md)

---

## Принципы алертинга

### 1. Alert Fatigue Prevention
- Только важные алерты
- Группировка похожих алертов
- Эскалация по времени

### 2. Alert Classification
- **Critical** — система недоступна
- **Warning** — деградация производительности
- **Info** — информационные уведомления

## Правила оповещений Prometheus

```yaml
# alerts.yml
groups:
- name: application
  rules:
  - alert: HighErrorRate
    expr: rate(http_requests_total{status=~"5.."}[5m]) / rate(http_requests_total[5m]) > 0.05
    for: 2m
    labels:
      severity: critical
    annotations:
      summary: "High error rate detected"
      description: "Error rate is {{ $value }} for {{ $labels.instance }}"
  
  - alert: HighResponseTime
    expr: histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m])) > 1
    for: 5m
    labels:
      severity: warning
    annotations:
      summary: "High response time"
      description: "95th percentile response time is {{ $value }}s"
```

## Конфигурация Alertmanager

```yaml
# alertmanager.yml
global:
  smtp_smarthost: 'localhost:587'
  smtp_from: 'alerts@example.com'

route:
  group_by: ['alertname']
  group_wait: 10s
  group_interval: 10s
  repeat_interval: 1h
  receiver: 'web.hook'

receivers:
- name: 'web.hook'
  webhook_configs:
  - url: 'http://alert-webhook:5001/alerts'
  
- name: 'email'
  email_configs:
  - to: 'admin@example.com'
    subject: 'Alert: {{ .GroupLabels.alertname }}'
    body: |
      {{ range .Alerts }}
      Alert: {{ .Annotations.summary }}
      Description: {{ .Annotations.description }}
      {{ end }}
```