How to configure Prometheus alerts?

· Category: DevOps & CI/CD

Short answer

Prometheus alerts are defined by recording and alerting rules. Alertmanager handles routing, grouping, and notification.

Steps

  1. Create alerting rules.
  2. Load them into Prometheus.
  3. Configure Alertmanager for routing.
  4. Set up notification channels.

Example

groups:
  - name: example
    rules:
      - alert: HighMemoryUsage
        expr: (node_memory_Active_bytes / node_memory_MemTotal_bytes) > 0.8
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High memory usage"

Tips

  • Use for to prevent flapping.
  • Group related alerts.
  • Route by severity.

Common issues

  • Alert fatigue from noisy rules.
  • Missing for causes false positives.
  • Alertmanager silences require maintenance.