Hands-On Reactive Programming in Spring 5

Adding custom Micrometer meters

In reactive streams, we may easily add a custom monitoring logic even without built-in support. For example, the following code explains how to add an invocation counter for a WebClient that does not have any default instrumentation:

WebClient.create(serviceUri)                                         // (1)
         .get()
         .exchange()
         .flatMap(cr -> cr.toEntity(User.class))                     // (2)
         .doOnTerminate(() -> registry
               .counter("user.request", "uri", serviceUri)           // (3)
               .increment())

Here, we create a new WebClient for a target serviceUri (1), make a request and deserialize the response to a User entity (2). When the operation is terminated, we manually increase the counter with a custom tag uri where the value represents serviceUri (3).

Similarly, we may combine ...