Tomcat and HTTP metrics missing if managment.server.port is set to a different port than server.port

[manderson23]

For a Spring Boot 2.1.x application where I set server.port and management.server.port to different ports I only see Tomcat and HTTP request metrics for server.port on /actuator/prometheus endpoint.

I would expect to see Tomcat metrics for both ports and HTTP metrics for requests on both ports.

[wilkinsona]

I suspect that some users have the opposite expectation and consider the current behaviour to be a feature rather than a bug, particularly while there's no tag to easily identify metrics for actuator endpoints (#13435).

[snicoll]

@manderson23 can you share why you need to monitor actuator endpoints?

[manderson23]

@snicoll I expected consistency across all our microservices deployed on K8s.

Most have only server.port set so we see /actuator/* calls in HTTP metrics on those. We have a couple of cases where both server.port and management.server.port to support SSL while keeping actuator as http. In that case I expected Tomcat and HTTP metrics across both ports.

High request rates to actuator could impact application performance so I don't think it would be unreasonable to have them available as metrics.

[wilkinsona]

#9560 is related to this. We have an inconsistent story around what is and isn't applied and configured when a separate management port has been configured that we'd like to straighten out. This is another part of that.