Scenario 2: Flag Missing for Clause in Alerting Rule

Context

A platform engineer submitted the following Prometheus alerting rule to monitor HTTP error rates. The rule should fire when the error rate exceeds 5% for a sustained period, not on transient spikes.

Alerting Rule Under Review

groups:
  - name: api-alerts
    rules:
      - alert: HighErrorRate
        expr: |
          rate(http_requests_total{job="api-service",status=~"5.."}[5m])
          /
          rate(http_requests_total{job="api-service"}[5m])
          > 0.05
        labels:
          severity: critical
        annotations:
          summary: "High error rate on API service"
          description: "Error rate is {{ $value | humanizePercentage }}"

Task

Produce two output files:

1. alert-review.md — a validation report that:

   • Identifies the missing for clause and explains why it causes alert storms on transient spikes.
   • Confirms the expression itself is well-formed (label filters present, correct use of rate() on a counter).
   • Recommends a minimum for duration and explains the trade-off between sensitivity and stability.

2. alert-corrected.yaml — the corrected alerting rule with:

   • A for clause added with an appropriate duration.
   • All other fields preserved exactly as in the input.

Output Specification

Produce alert-review.md and alert-corrected.yaml.