Starting with Version 3.2, Project Reactor itself added an essential integration with the Micrometer library. Project Reactor works fine without the Micrometer library, but in case it detects a Micrometer presence in the application's classpath, it may report some elemental metrics that may reveal valuable insights about application operational conditions. Now it is time to describe how to monitor reactive streams using built-in functions and how to add custom meters for the desired operational aspects.
Project Reactor 3.2 is bundled with Spring Framework 5.1 and Spring Boot 2.1. However, in general, it is possible to bump the reactor version even for applications with Spring Framework 5.0 and Spring Boot 2.0. Furthermore, all the code related to custom metric registration should work fine with previous versions of Project Reactor.