Prometheus is the de facto standard for application metrics. This presentation explains what Prometheus is, how it works, and how to use it in detail.
Update: With OpenTelemetry there exists a new instrumentation framework, which does not only support metrics but also traces.
Slides
Further Information
Metric types
Instrumentation
- https://prometheus.io/docs/practices/instrumentation/
- https://docs.spring.io/spring-boot/docs/2.7.x/reference/htmlsingle/#actuator.metrics