In this chapter, we had the opportunity to observe a different way to produce a derivative time series. Recording rules help improve monitoring system stability and performance when recurrent heavy queries are required by pre-computing them into new time series that are comparatively cheap to consult. Alerting rules bring the power and flexibility of PromQL to alerts; they enable triggering alerts for complex and dynamic thresholds as well as targeting multiple instances or even different applications using a single alert rule. Having a good grasp on how delays are introduced in alerts will now help you tailor them to your needs, but remember, a little delay is better than noisy alerts. Finally, we explored how to create unit tests for our rules and validate them even before a Prometheus server is running.

The next chapter will step into another component of monitoring: visualization. We'll be diving into Grafana, the community-preferred choice for Prometheus-powered dashboards.