ServerHttpObservationFilter does not fill pathPattern

[bergerdenes]

Affects: 6.0.15, 6.1.3

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This property is necessary for collecting metrics via Micrometer.

In the org.springframework.http.server.observation.DefaultServerRequestObservationConvention class, the protected KeyValue uri(ServerRequestObservationContext context) method tries to get context.getPathPattern() but it is always null.

[bclozel]

We have tests that check for this case. Can you elaborate? What's the endpoint? Can your provide a minimal sample application that reproduces the problem?

[bergerdenes]

Repro repository: https://github.com/bergerdenes/metrics-repro
Similar issue reported (and others referenced within): #31028

[bclozel]

I'm sorry I can't reproduce the problem. I ran many requests on my local machine, including using benchmarking tools and I'm seeing:

$ curl localhost:8080/metrics | grep ^http_server_requests_seconds

http_server_requests_seconds{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/metrics",quantile="0.5",} 0.0
http_server_requests_seconds{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/metrics",quantile="0.95",} 0.0
http_server_requests_seconds_count{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/metrics",} 5.0
http_server_requests_seconds_sum{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/metrics",} 0.066770067
http_server_requests_seconds{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",quantile="0.5",} 0.007856128
http_server_requests_seconds{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",quantile="0.95",} 0.016769024
http_server_requests_seconds_count{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",} 30016.0
http_server_requests_seconds_sum{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",} 256.0871663
http_server_requests_seconds_max{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/metrics",} 0.007237065
http_server_requests_seconds_max{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",} 0.054313366

Thoughts?

[bergerdenes]

My output for the same:

http_server_requests_active_seconds_max{exception="none",method="GET",outcome="SUCCESS",status="200",uri="UNKNOWN",} 0.038592375
http_server_requests_active_seconds{exception="none",method="GET",outcome="SUCCESS",status="200",uri="UNKNOWN",quantile="0.5",} 0.0385395
http_server_requests_active_seconds{exception="none",method="GET",outcome="SUCCESS",status="200",uri="UNKNOWN",quantile="0.95",} 0.038592375
http_server_requests_active_seconds_active_count{exception="none",method="GET",outcome="SUCCESS",status="200",uri="UNKNOWN",} 1.0
http_server_requests_active_seconds_duration_sum{exception="none",method="GET",outcome="SUCCESS",status="200",uri="UNKNOWN",} 0.038580208
http_server_requests_seconds{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",quantile="0.5",} 0.001409024
http_server_requests_seconds{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",quantile="0.95",} 0.01622016
http_server_requests_seconds_count{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",} 3.0
http_server_requests_seconds_sum{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",} 0.018441751
http_server_requests_seconds_max{error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/test",} 0.016043917

[bclozel]

I'm only seeing "UNKNOWN" tags for the http_server_requests_active metric, which is expected. For each observation, the Micrometer metrics handler creates a long task timer that measures ongoing requests. This tag value is expected for those, as tags are collected as soon as the observation starts; at this stage, the instrumentation cannot know on which controller handler the request will be mapped.

That is an interesting point, though. If you believe that this is confusing, or if you'd like to have an option to disable those long task timers, please raise a Micrometer issue in order to discuss this matter with the team. The metrics handler code is managed by Micrometer directly.

In light of that, I'm closing this issue. Thanks!