Apache Tomcat Metrics Instrumentation

The Apache Tomcat software is an open source implementation of the Jakarta Servlet, Jakarta Server Pages, Jakarta Expression Language, Jakarta WebSocket, Jakarta Annotations and Jakarta Authentication specifications.

// Setting up instrumentation
SimpleMeterRegistry registry = new SimpleMeterRegistry(SimpleConfig.DEFAULT, new MockClock());


Iterable<Tag> tags = Tags.of("metricTag", "val1");
TomcatMetrics.monitor(registry, manager, tags);

// Example of Tomcat metrics
assertThat(registry.get("tomcat.sessions.active.max").tags(tags).gauge().value()).isEqualTo(3.0);
assertThat(registry.get("tomcat.sessions.active.current").tags(tags).gauge().value()).isEqualTo(2.0);
assertThat(registry.get("tomcat.sessions.expired").tags(tags).functionCounter().count()).isEqualTo(1.0);
assertThat(registry.get("tomcat.sessions.rejected").tags(tags).functionCounter().count()).isEqualTo(1.0);
assertThat(registry.get("tomcat.sessions.created").tags(tags).functionCounter().count()).isEqualTo(3.0);
assertThat(registry.get("tomcat.sessions.alive.max").tags(tags).timeGauge().value()).isGreaterThan(1.0);