Request Flask attributes passed to Sampler (#1784)

* Request Flask attributes passed to Sampler

* Update changelog

* Lint

* Fix botocore test keyerror

* Revert "Fix botocore test keyerror"

This reverts commit fd03c55a3902b3456afd6a2ecf429afba11b0691.

* botocore test does get_queue_url

* Revert "botocore test does get_queue_url"

This reverts commit 9530cd250dd836b3181a9361decb130e2aae1202.

* Update changelog

---------

Co-authored-by: Srikanth Chekuri <srikanth.chekuri92@gmail.com>
Co-authored-by: Shalev Roda <65566801+shalevr@users.noreply.github.com>

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- Make Flask request span attributes available for `start_span`. 
+  ([#1784](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1784))
 - Fix falcon instrumentation's usage of Span Status to only set the description if the status code is ERROR.
   ([#1840](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1840))
 - Instrument all httpx versions >= 0.18. ([#1748](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1748))

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

@@ -375,27 +375,26 @@ def _wrapped_before_request(
         flask_request_environ = flask.request.environ
         span_name = get_default_span_name()
 
-        span, token = _start_internal_or_server_span(
-            tracer=tracer,
-            span_name=span_name,
-            start_time=flask_request_environ.get(_ENVIRON_STARTTIME_KEY),
-            context_carrier=flask_request_environ,
-            context_getter=otel_wsgi.wsgi_getter,
-        )
-
-        if request_hook:
-            request_hook(span, flask_request_environ)
-
-        if span.is_recording():
         attributes = otel_wsgi.collect_request_attributes(
             flask_request_environ
         )
         if flask.request.url_rule:
             # For 404 that result from no route found, etc, we
             # don't have a url_rule.
-                attributes[
-                    SpanAttributes.HTTP_ROUTE
-                ] = flask.request.url_rule.rule
+            attributes[SpanAttributes.HTTP_ROUTE] = flask.request.url_rule.rule
+        span, token = _start_internal_or_server_span(
+            tracer=tracer,
+            span_name=span_name,
+            start_time=flask_request_environ.get(_ENVIRON_STARTTIME_KEY),
+            context_carrier=flask_request_environ,
+            context_getter=otel_wsgi.wsgi_getter,
+            attributes=attributes,
+        )
+
+        if request_hook:
+            request_hook(span, flask_request_environ)
+
+        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: