GuideObservability
Why a Prometheus error-rate query can return no data
Zero errors, no traffic and absent series produce different PromQL results. Synthetic tests show how ratios, fallback zeros and absence checks behave for a checkout service.
Prometheus
Guides, news and explanations about AI and reliable systems.
GuideObservability
Grafana dashboards for incident response
Regional failures can disappear in fleet averages. Grafana queries, population labels and linked traces help responders find the affected requests.