opentelemetry-instrumentation-falcon: pass request attributes at span creation (#4119)

* opentelemetry-instrumentation-falcon: pass request attributes at span creation

To ease sampling work.

* Add changelog

Author: xrmx

CHANGELOG.md

@@ -39,6 +39,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#4099](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4099))
 - `opentelemetry-instrumentation-aiohttp-server` Implement new semantic convention opt-in migration
   ([#3980](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3980))
+- `opentelemetry-instrumentation-falcon`: pass request attributes at span creation
+  ([#4119](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4119))
 - `opentelemetry-instrumentation`: add database stability attribute setters in `_semconv` utilities
   ([#4108](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4108))
 - `opentelemetry-instrumentation-tornado`: Implement new semantic convention opt-in migration

instrumentation/opentelemetry-instrumentation-falcon/src/opentelemetry/instrumentation/falcon/__init__.py

@@ -368,15 +368,16 @@ def __call__(self, env, start_response):
 
         start_time = time_ns()
 
+        attributes = otel_wsgi.collect_request_attributes(
+            env, self._sem_conv_opt_in_mode
+        )
         span, token = _start_internal_or_server_span(
             tracer=self._otel_tracer,
             span_name=otel_wsgi.get_default_span_name(env),
             start_time=start_time,
             context_carrier=env,
             context_getter=otel_wsgi.wsgi_getter,
-        )
-        attributes = otel_wsgi.collect_request_attributes(
-            env, self._sem_conv_opt_in_mode
+            attributes=attributes,
         )
         active_requests_count_attrs = (
             otel_wsgi._parse_active_request_count_attrs(
@@ -386,8 +387,6 @@ def __call__(self, env, start_response):
         self.active_requests_counter.add(1, active_requests_count_attrs)
 
         if span.is_recording():
-            for key, value in attributes.items():
-                span.set_attribute(key, value)
             if span.is_recording() and span.kind == trace.SpanKind.SERVER:
                 custom_attributes = (
                     otel_wsgi.collect_custom_request_headers_attributes(env)