What rules are involved in setting up and using alerts in monitoring systems?

Setting up and using alerts in monitoring systems typically includes the following rules:

• Defining metrics and thresholds: Key metrics (e.g., CPU load, memory usage, response time) are selected, and threshold values are set, exceeding which triggers an alert.

• Levels of importance: Alerts are classified by criticality level (informational, warning, critical) to respond appropriately to different situations.

• Trigger conditions: Conditions are configured, such as exceeding a threshold for a certain period, to avoid false alarms.

• Grouping and deduplication: Rules for combining similar alerts and preventing notification spam.

• Assigning responsible persons: Responsible individuals or teams are designated to receive notifications.

• Notification channels: Notification methods are set up — email, SMS, messengers, integrations with incident systems.

• Testing and regular review: Alerts should be tested for correctness and periodically reviewed to remain relevant.

Example of setting up an alert in Prometheus Alertmanager:

groups:
- name: example
  rules:
  - alert: HighCpuUsage
    expr: avg(rate(cpu_usage_seconds_total[5m])) > 0.8
    for: 5m
    labels:
      severity: critical
    annotations:
      summary: "High CPU load"
      description: "CPU is loaded over 80% for 5 minutes"