Monitoring our monitoring: how we validate our Prometheus alert rules

What this post added

This post details Cloudflare's use of Prometheus as its core monitoring system and introduces a new open-source tool developed to validate Prometheus alert rules. It explains the potential pitfalls of alert rule creation, such as typos or incorrect query logic, leading to silent failures where alerts don't fire when they should. The post elaborates on Prometheus querying basics (instant vs. range queries) and how these can lead to unexpected empty results, impacting alert reliability. The contribution lies in addressing the critical aspect of ensuring the accuracy and trustworthiness of the monitoring system itself, thereby improving the overall observability platform.