Micrometer is a dimensional-first metrics collection facade whose aim is to allow you to time, count, and gauge your code with a vendor neutral API. Through classpath and configuration, you may select one or several monitoring systems to export your metrics data to. Think of it like SLF4J, but for metrics!
Micrometer is the metrics collection facility included in Spring Boot 2’s Actuator. It has also been backported to Spring Boot 1.5, 1.4, and 1.3 with the addition of another dependency.
Micrometer adds richer meter primitives to the counters and gauges that existed in Spring Boot 1. For example, a single Micrometer
Timer is capable of producing time series related to throughput, total time, maximum latency of recent samples, pre-computed percentiles, percentile histograms, and SLA boundary counts.
Despite its focus on dimensional metrics, Micrometer does map to hierarchical names to continue to serve older monitoring solutions like Ganglia or narrower scoped tools like JMX. The change to Micrometer arose out of a desire to better serve a wave of dimensional monitoring systems (think Prometheus, Datadog, Wavefront, SignalFx, Influx, etc). One of Spring’s strengths is the enablement of choice through abstraction. By integrating with Micrometer, Spring Boot is enabling you to choose one or more monitoring systems to use today, and change your mind later as your needs change without requiring a rewrite of your custom metrics instrumentation.
Before opting to develop "yet another" metrics collection library, we looked hard at existing or up-and-coming dimensional collectors. But as we looked at exporting to more and more monitoring systems, the importance of the structure of names and data became apparent. Micrometer builds in concepts of naming convention normalization, base unit of time scaling, and support for proprietary expressions of structures like histogram data that are essential to make metrics shine in each target system. Along the way, we added meter filtering as well, allowing you to exercise greater control over the instrumentation of your upstream dependencies.