ASP.NET http.route appears to be incorrect when exception handlers are invoked

[tyler-boyd]

Bug Report

List of all OpenTelemetry NuGet
packages and version that you are
using (e.g. OpenTelemetry 1.0.2):

• OpenTelemetry 1.7.0
• OpenTelemetry.Instrumentation.AspNetCore 1.7.0

Runtime version (e.g. net462, net48, netcoreapp3.1, net6.0 etc. You can
find this information from the *.csproj file):

• net8

Symptom

A clear and concise description of what the bug is.

What is the expected behavior?

http.route should always be populated, regardless of if the route handler threw an exception or not.

What is the actual behavior?

http.route is only populated when there's no exception; the tag is null when an exception occurs.

Reproduce

In lieu of a reproduction repo, I can point to the likely cause, which is a discrepancy between how the metrics instrumentation handles http.route compared to the tracing instrumentation.

• Metrics:

  opentelemetry-dotnet/src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpInMetricsListener.cs

  Lines 90 to 96 in 84bdeb3

  	// Check the exception handler feature first in case the endpoint was overwritten
  	var route = (context.Features.Get<IExceptionHandlerPathFeature>()?.Endpoint as RouteEndpoint ??
  	context.GetEndpoint() as RouteEndpoint)?.RoutePattern.RawText;
  	if (!string.IsNullOrEmpty(route))
  	{
  	tags.Add(new KeyValuePair<string, object>(SemanticConventions.AttributeHttpRoute, route));
  	}

  , note that it checks context.Features.Get<IExceptionHandlerPathFeature>()?.Endpoint first, falling back to context.GetEndpoint()
• Tracing:

  opentelemetry-dotnet/src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpInListener.cs

  Lines 246 to 252 in 84bdeb3

  	var routePattern = (context.Features.Get<IExceptionHandlerPathFeature>()?.Endpoint as RouteEndpoint ??
  	context.GetEndpoint() as RouteEndpoint)?.RoutePattern.RawText;
  	if (!string.IsNullOrEmpty(routePattern))
  	{
  	RequestMethodHelper.SetActivityDisplayName(activity, context.Request.Method, routePattern);
  	activity.SetTag(SemanticConventions.AttributeHttpRoute, routePattern);
  	}

  , note it only checks context.GetEndpoint()

I'd assume the metrics way is correct, but am not positive 🤷‍♂️

[CodeBlanch]

@tyler-boyd I think this was fixed by: #5135

Would you mind trying 1.7.1 or newer and report back?

[alanwest]

Ah and you also mentioned that you're using net8. The instrumentation in this repository only emits metrics for net6 and net7. With net8 the http.server.request.duration metric is emitted natively by the ASP.NET Core itself.

See comment in the release notes.

Fixed an issue where the http.route attribute was not set on either the Activity or http.server.request.duration metric generated from a request when an exception handling middleware is invoked. One caveat is that this fix does not address the problem for the http.server.request.duration metric when running ASP.NET Core 8. ASP.NET Core 8 contains an equivalent fix which should ship in version 8.0.2 (see: dotnet/aspnetcore#52652). (#5135).

You'll need to update to ASP.NET Core 8.0.2+

[tyler-boyd]

Thanks for the quick replies, I didn't see that linked issue because I was searching for http.route (which isn't explicitly mentioned).

Updating to the latest version of these libraries did the trick, I should have tried that before opening an issue 🙂 Thanks again!