span name is not better with Java filter use

[LifaPeng]

Describe the bug

The server receives requests for /test/otle and processes them in a Java filter with registration.addUrlPatterns("/test/*").

However, due to the initial route being null, the method HttpServerRoute.isBetterRoute(httpRouteState, route) always returns true, triggering the subsequent call to updateSpanName(serverSpan, httpRouteState, route), which updates the span name to /test/*.

Steps to reproduce

The server receives requests for /test/otle and processes them in a Java filter with registration.addUrlPatterns("/test/*").
The Java filter returns directly without executing chain.doFilter(request, response).

Expected behavior

In this case, /test/otle is longer than /test/*, and it is expected to use /test/otle as the final span name.

Actual behavior

now is /test/*

Javaagent or library instrumentation version

2.5.0+

Environment

JDK:
OS:

Additional context

No response

[laurit]

In this case, /test/otle is longer than /test/*, and it is expected to use /test/otle as the final span name.

https://opentelemetry.io/docs/specs/semconv/http/http-spans/#name states that request URI path may not be used for span name because it could have high cardinality. We use the path where servlet or filter that service the request is mapped as this is guaranteed to have low cardinality. If needed you can manually set a better route/span name.

[LifaPeng]

When not using a Java filter, the URL seems to be used as the span name. Is there a way to obtain the current span name during the execution of isBetterRoute to compare it with the route?
Alternatively, how can a better route/span name be set without modifying the program code?

[trask]

Alternatively, how can a better route/span name be set without modifying the program code?

you could write a Java agent extension and wrap the exporter to update the span name based on the span attributes (e.g. using url.path)

[LifaPeng]

Is there an example or practical documentation that can guide us? Thank you.

[trask]

sorry, I should have included the link, check out https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/main/examples/extension

[breedx-splk]

@LifaPeng will writing an extension then work for you? Thanks.

[LifaPeng]

I'll try following the link