Workers Automatic Tracing: span name only shows HTTP method, not route pattern (e.g. `GET` instead of `GET /foo/{id}`)

[willie]

Follow-up from discussion #11062.

Current behavior: The span name / resource attribute for incoming request spans is just the HTTP method (e.g. GET).

Expected behavior: The span name should include the route/endpoint pattern, e.g. GET /foo/{id}, similar to how most HTTP server instrumentations name root spans ({method} {route} per OTel semantic conventions).

Without the route pattern, APM tools (reported independently for Datadog and Kibana in the linked discussion) can't group/aggregate spans by endpoint — every request under a given method collapses into a single span name regardless of which route handled it.

cc @jmorrell-cloudflare @nevikashah (from the linked discussion)

[jmorrell-cloudflare]

I'm afraid this is a fundamental limitation for now. There is no way to statically analyze or deduce the user's routing logic which is particular to their worker. They may use a router library, or a set of if statements, or... anything really. Given we don't have this data, naming with just the { method } is the recommended approach per OTel semantic conventions, though we understand that this is not ideal.

The fix is to be able to override the name of the root span so that the user (or ideally the HTTP framework itself) can override the name and add the route as an attribute. This is something we are working on.

[willie]

Yes, the latter is exactly what I'm used to from other languages and OTEL SDKs, that would be ideal.