An Istio 1.32 DestinationRule sets outlierDetection.failurePercentageThreshold: 30 for a busy service with three pods. Why is no pod ever ejected for its failure rate?

Answer: Envoy skips failure percentage ejection in clusters with fewer than 5 hosts

Explanation

Istio sets the threshold and enables enforcement but leaves Envoy's failure_percentage_minimum_hosts at its default of 5, and failure_percentage_request_volume at 50 requests per interval. A three-pod service is below the host minimum, so only the consecutive error counters can eject its pods.