Fix ASGIGetter keys to fetch from actual carrier headers

CHANGELOG.md

@@ -14,6 +14,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `opentelemetry-instrumentation-aws-lambda` Adds an option to configure `disable_aws_context_propagation` by
   environment variable: `OTEL_LAMBDA_DISABLE_AWS_CONTEXT_PROPAGATION`
   ([#1507](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1507))
+- `opentelemetry-instrumentation-asgi` Fix keys() in class ASGIGetter to correctly fetch values from carrier headers.
+  ([#1435](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1435))
 
 
 ## Version 1.15.0/0.36b0 (2022-12-10)

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

@@ -260,7 +260,8 @@ def get(
         return decoded
 
     def keys(self, carrier: dict) -> typing.List[str]:
-        return [_key.decode("utf8") for (_key, _value) in carrier]
+        headers = carrier.get("headers") or []
+        return [_key.decode("utf8") for (_key, _value) in headers]
 
 
 asgi_getter = ASGIGetter()

instrumentation/opentelemetry-instrumentation-asgi/tests/test_asgi_custom_headers.py

@@ -1,6 +1,18 @@
+import typing
 from unittest import mock
 
 import opentelemetry.instrumentation.asgi as otel_asgi
+from opentelemetry import trace
+from opentelemetry.context import Context
+from opentelemetry.propagate import get_global_textmap, set_global_textmap
+from opentelemetry.propagators.textmap import (
+    CarrierT,
+    Getter,
+    Setter,
+    TextMapPropagator,
+    default_getter,
+    default_setter,
+)
 from opentelemetry.test.asgitestutil import AsgiTestBase
 from opentelemetry.test.test_base import TestBase
 from opentelemetry.trace import SpanKind
@@ -13,6 +25,60 @@
 from .test_asgi_middleware import simple_asgi
 
 
+class MockTextMapPropagator(TextMapPropagator):
+    """Mock propagator for testing purposes using both getter `get` and `all`."""
+
+    TRACE_ID_KEY = "mock-traceid"
+    SPAN_ID_KEY = "mock-spanid"
+
+    def extract(
+        self,
+        carrier: CarrierT,
+        context: typing.Optional[Context] = None,
+        getter: Getter = default_getter,
+    ) -> Context:
+        if context is None:
+            context = Context()
+
+        trace_id_list = getter.get(carrier, self.TRACE_ID_KEY)
+        span_id_list = getter.get(carrier, self.SPAN_ID_KEY)
+        carrier_keys = getter.keys(carrier)
+
+        if not trace_id_list or not span_id_list:
+            assert not any(key in carrier_keys for key in self.fields)
+            return context
+
+        assert all(key in carrier_keys for key in self.fields)
+        return trace.set_span_in_context(
+            trace.NonRecordingSpan(
+                trace.SpanContext(
+                    trace_id=int(trace_id_list[0]),
+                    span_id=int(span_id_list[0]),
+                    is_remote=True,
+                )
+            ),
+            context,
+        )
+
+    def inject(
+        self,
+        carrier: CarrierT,
+        context: typing.Optional[Context] = None,
+        setter: Setter = default_setter,
+    ) -> None:
+        span = trace.get_current_span(context)
+        setter.set(
+            carrier, self.TRACE_ID_KEY, str(span.get_span_context().trace_id)
+        )
+        setter.set(
+            carrier, self.SPAN_ID_KEY, str(span.get_span_context().span_id)
+        )
+
+    @property
+    def fields(self):
+        return {self.TRACE_ID_KEY, self.SPAN_ID_KEY}
+
+
 async def http_app_with_custom_headers(scope, receive, send):
     message = await receive()
     assert scope["type"] == "http"
@@ -34,6 +100,8 @@ async def http_app_with_custom_headers(scope, receive, send):
                         b"my-custom-regex-value-3,my-custom-regex-value-4",
                     ),
                     (b"my-secret-header", b"my-secret-value"),
+                    (MockTextMapPropagator.TRACE_ID_KEY.encode(), b"1"),
+                    (MockTextMapPropagator.SPAN_ID_KEY.encode(), b"2"),
                 ],
             }
         )
@@ -60,6 +128,8 @@ async def websocket_app_with_custom_headers(scope, receive, send):
                             b"my-custom-regex-value-3,my-custom-regex-value-4",
                         ),
                         (b"my-secret-header", b"my-secret-value"),
+                        (MockTextMapPropagator.TRACE_ID_KEY.encode(), b"1"),
+                        (MockTextMapPropagator.SPAN_ID_KEY.encode(), b"2"),
                     ],
                 }
             )
@@ -88,6 +158,11 @@ def setUp(self):
         self.app = otel_asgi.OpenTelemetryMiddleware(
             simple_asgi, tracer_provider=self.tracer_provider
         )
+        self.previous_propagator = get_global_textmap()
+        set_global_textmap(MockTextMapPropagator())
+
+    def tearDown(self):
+        set_global_textmap(self.previous_propagator)
 
     def test_http_custom_request_headers_in_span_attributes(self):
         self.scope["headers"].extend(