Incorrect HTTP status recorded when using custom exception handler

[danielksb]

Expected Behavior

When running a Micronaut server with a custom exception handler that maps specific exceptions to HTTP statuses other than 500, the metrics incorrectly record the status as 500. This issue arises when using Micronaut versions 4.7.x and above, whereas the expected behavior was observed in version 4.6.x.

Given

• an exception "DemoException"
• an endpoint "GET /api/error" which triggers the exception
• a CustomExceptionHandler implementing ExceptionHandler<DemoException, HttpResponse> responding with http status 400

Upon invoking the endpoint that triggers the DemoException, the expected metric should be:

http_server_requests_seconds_count{exception="none",method="GET",status="400",uri="/api/error"} 1

Actual Behaviour

Instead of recording the expected status, the metric is:

http_server_requests_seconds_count{exception="DemoException",method="GET",status="500",uri="/api/error"} 1

Steps To Reproduce

Please see the example in the repository below.

Environment Information

• Previous Version: This behavior was functioning correctly in Micronaut version 4.6.x.
• Current Version: The issue began occurring with the release of Micronaut version 4.7.x and continues in subsequent versions.

Example Application

https://github.com/danielksb/micronaut-demo-micrometer-bug

Version

4.7.x

[SushmaReddyLoka]

We are also seeing similar issue on 4.7.5 version, we are emitting bad request status code 400 from the exception handler but the metrics is capturing it as 500.
Till the fix is available is there any way to work around this problem, as we are heavily relying on the metrics.

[SaiYashasvi9]

Is there any work around available?

[SushmaReddyLoka]

@graemerocher , @jameskleeh @sdelamo can you provider your inputs on this issue.

[graemerocher]

I guess you can disable the built-in default metrics and write your own version of

micronaut-micrometer/micrometer-core/src/main/java/io/micronaut/configuration/metrics/binder/web/ServerMetricsFilter.java

Line 53 in f5c0fd0

final class ServerMetricsFilter {

in the meantime

[frank-mueller-at-kiwigrid-com]

The behavior change sounds similar to #925
Try to upgrade io.micronaut.micrometer:micronaut-micrometer-core to 5.10.0

[kevin-wise]

It does sound like #928 would fix it. Any chance we can get a backport of that for 5.9.x?