HTTP Method column missing as OTEL attribute doesn't appear to parse

[JLuse]

Package

Sentry

.NET Flavor

.NET

.NET Version

7.0.11

OS

Android

SDK Version

3.39.1

Self-Hosted Sentry Version

No response

Steps to Reproduce

Description
Reported from a customer integrating OTEL, that when viewing their performance page, the HTTP Method column contains all empty values. However, the OTEL attribute associated with the event has the method included:

Customer support ticket: https://sentry.zendesk.com/agent/tickets/103357
Steps to reproduce:

1. Instrument OTEL - https://docs.sentry.io/platforms/dotnet/performance/instrumentation/opentelemetry/
2. Send transaction -> view in Sentry project

Expected Result

The span processor should adjust by setting the request context on the event, populating the HTTP methods

Actual Result

Column is empty:

[jamescrosswell]

Thanks @JLuse , I can reproduce this so we should be able to get to the bottom of it.

For some reason, the transaction.Request context isn't being set correctly - which would normally be done in the scope.
Our Middleware hooks things up so the Scope gets populated when it's evaluated:

sentry-dotnet/src/Sentry.AspNetCore/SentryMiddleware.cs

Lines 118 to 122 in 55ca61e

	scope.OnEvaluating += (_, activeScope) =>
	{
	SyncOptionsScope(activeScope);
	PopulateScope(context, activeScope);
	};

And our Hub evalulates and applies this when capturing a transaction:

sentry-dotnet/src/Sentry/Internal/Hub.cs

Lines 484 to 488 in 0ae99b1

	// Apply scope data
	var currentScopeAndClient = ScopeManager.GetCurrent();
	var scope = currentScopeAndClient.Key;
	scope.Evaluate();
	scope.Apply(transaction);

This isn't working with OpenTelemetry however. Hub.CatpureTransaction gets called but, the scope that it retrieves from the ScopeManager doesn't have any Scope.OnEvaluating callback configured... which makes me think it's not the same scope that was configured by our Middleware.

Needs some investigation.

[jamescrosswell]

OK, tricky. I think what's going on here is that our Scopes are managed via SentryScopeManager which, in the case of ASP.NET Core, leverages an AsyncLocalScopeStackContainer internally:

sentry-dotnet/src/Sentry/Internal/SentryScopeManager.cs

Lines 24 to 27 in efb5dc8

	ScopeStackContainer = options.ScopeStackContainer ?? (
	options.IsGlobalModeEnabled
	? new GlobalScopeStackContainer()
	: new AsyncLocalScopeStackContainer());

That means the scopes stick with an asynchronous control flow.

However the OpenTelemetry integration for ASP.NET Core appears to subscribe to system diagnostics events... I'm not familiar enough with the OpenTelemetry codebase to see the exact path between those diagnostic events and calling our SpanProcessor, but I think the TLDR; is that the SentrySpanProcessor.OnEnd event (which is where we finish open telemetry transactions) is not being executed in the same async local context as the SentryMiddleware. As a consequence, the scope is not being applied correctly to spans captured via OpenTelemetry 😢