Fix for FASTAPI unable to record AppService URL (Issue #3654)

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 > Use [this search for a list of all CHANGELOG.md files in this repo](https://github.com/search?q=repo%3Aopen-telemetry%2Fopentelemetry-python-contrib+path%3A**%2FCHANGELOG.md&type=code).
 
 ## Unreleased
+- `opentelemetry-instrumentation-asgi` Fixed issue where FastAPI reports IP instead of URL.
+  ([#3670](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3670))
 
 ### Fixed
 
@@ -44,7 +46,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Version 1.36.0/0.57b0 (2025-07-29)
 
 ### Fixed
-
 - `opentelemetry-instrumentation`: Fix dependency conflict detection when instrumented packages are not installed by moving check back to before instrumentors are loaded. Add "instruments-any" feature for instrumentations that target multiple packages.
   ([#3610](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3610))
 - infra(ci): Fix git pull failures in core contrib test

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

@@ -445,15 +445,30 @@ def get_host_port_url_tuple(scope):
     """Returns (host, port, full_url) tuple."""
     server = scope.get("server") or ["0.0.0.0", 80]
     port = server[1]
+
+    host_header = asgi_getter.get(scope, "host")
+    if host_header:
+        host_value = host_header[0]
+        # Ensure host_value is a string, not bytes
+        if isinstance(host_value, bytes):
+            host_value = _decode_header_item(
+                host_value
+            )  # use existing function
+
+        url_host = host_value
+
+    else:
+        url_host = server[0] + (":" + str(port) if str(port) != "80" else "")
     server_host = server[0] + (":" + str(port) if str(port) != "80" else "")
+
     # using the scope path is enough, see:
     # - https://asgi.readthedocs.io/en/latest/specs/www.html#http-connection-scope (see: root_path and path)
     # - https://asgi.readthedocs.io/en/latest/specs/www.html#wsgi-compatibility (see: PATH_INFO)
     #       PATH_INFO can be derived by stripping root_path from path
     #       -> that means that the path should contain the root_path already, so prefixing it again is not necessary
     # - https://wsgi.readthedocs.io/en/latest/definitions.html#envvar-PATH_INFO
     full_path = scope.get("path", "")
-    http_url = scope.get("scheme", "http") + "://" + server_host + full_path
+    http_url = scope.get("scheme", "http") + "://" + url_host + full_path
     return server_host, port, http_url
 
 

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

@@ -780,7 +780,10 @@ async def test_host_header(self):
 
         def update_expected_server(expected):
             expected[3]["attributes"].update(
-                {SpanAttributes.HTTP_SERVER_NAME: hostname.decode("utf8")}
+                {
+                    SpanAttributes.HTTP_SERVER_NAME: hostname.decode("utf8"),
+                    SpanAttributes.HTTP_URL: f"http://{hostname.decode('utf8')}/",
+                }
             )
             return expected
 
@@ -797,7 +800,10 @@ async def test_host_header_both_semconv(self):
 
         def update_expected_server(expected):
             expected[3]["attributes"].update(
-                {SpanAttributes.HTTP_SERVER_NAME: hostname.decode("utf8")}
+                {
+                    SpanAttributes.HTTP_SERVER_NAME: hostname.decode("utf8"),
+                    SpanAttributes.HTTP_URL: f"http://{hostname.decode('utf8')}/",
+                }
             )
             return expected
 
@@ -1728,7 +1734,7 @@ def test_request_attributes(self):
                 SpanAttributes.HTTP_METHOD: "GET",
                 SpanAttributes.HTTP_HOST: "127.0.0.1",
                 SpanAttributes.HTTP_TARGET: "/",
-                SpanAttributes.HTTP_URL: "http://127.0.0.1/?foo=bar",
+                SpanAttributes.HTTP_URL: "http://test/?foo=bar",
                 SpanAttributes.NET_HOST_PORT: 80,
                 SpanAttributes.HTTP_SCHEME: "http",
                 SpanAttributes.HTTP_SERVER_NAME: "test",
@@ -1781,7 +1787,7 @@ def test_request_attributes_both_semconv(self):
                 SpanAttributes.HTTP_METHOD: "GET",
                 SpanAttributes.HTTP_HOST: "127.0.0.1",
                 SpanAttributes.HTTP_TARGET: "/",
-                SpanAttributes.HTTP_URL: "http://127.0.0.1/?foo=bar",
+                SpanAttributes.HTTP_URL: "http://test/?foo=bar",
                 SpanAttributes.NET_HOST_PORT: 80,
                 SpanAttributes.HTTP_SCHEME: "http",
                 SpanAttributes.HTTP_SERVER_NAME: "test",

instrumentation/opentelemetry-instrumentation-django/tests/test_middleware_asgi.py

@@ -174,7 +174,7 @@ async def test_templated_route_get(self):
         self.assertEqual(span.attributes[SpanAttributes.HTTP_METHOD], "GET")
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_URL],
-            "http://127.0.0.1/route/2020/template/",
+            "http://testserver/route/2020/template/",
         )
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_ROUTE],
@@ -219,7 +219,7 @@ async def test_templated_route_get_both_semconv(self):
         self.assertEqual(span.attributes[SpanAttributes.HTTP_METHOD], "GET")
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_URL],
-            "http://127.0.0.1/route/2020/template/",
+            "http://testserver/route/2020/template/",
         )
         self.assertEqual(span.attributes[SpanAttributes.HTTP_SCHEME], "http")
         self.assertEqual(span.attributes[SpanAttributes.HTTP_STATUS_CODE], 200)
@@ -248,7 +248,7 @@ async def test_traced_get(self):
         self.assertEqual(span.attributes[SpanAttributes.HTTP_METHOD], "GET")
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_URL],
-            "http://127.0.0.1/traced/",
+            "http://testserver/traced/",
         )
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_ROUTE], "^traced/"
@@ -289,7 +289,7 @@ async def test_traced_get_both_semconv(self):
         self.assertEqual(span.attributes[SpanAttributes.HTTP_METHOD], "GET")
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_URL],
-            "http://127.0.0.1/traced/",
+            "http://testserver/traced/",
         )
         self.assertEqual(span.attributes[SpanAttributes.HTTP_SCHEME], "http")
         self.assertEqual(span.attributes[SpanAttributes.HTTP_STATUS_CODE], 200)
@@ -328,7 +328,7 @@ async def test_traced_post(self):
         self.assertEqual(span.attributes[SpanAttributes.HTTP_METHOD], "POST")
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_URL],
-            "http://127.0.0.1/traced/",
+            "http://testserver/traced/",
         )
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_ROUTE], "^traced/"
@@ -369,7 +369,7 @@ async def test_traced_post_both_semconv(self):
         self.assertEqual(span.attributes[SpanAttributes.HTTP_METHOD], "POST")
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_URL],
-            "http://127.0.0.1/traced/",
+            "http://testserver/traced/",
         )
         self.assertEqual(span.attributes[SpanAttributes.HTTP_SCHEME], "http")
         self.assertEqual(span.attributes[SpanAttributes.HTTP_STATUS_CODE], 200)
@@ -396,7 +396,7 @@ async def test_error(self):
         self.assertEqual(span.attributes[SpanAttributes.HTTP_METHOD], "GET")
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_URL],
-            "http://127.0.0.1/error/",
+            "http://testserver/error/",
         )
         self.assertEqual(span.attributes[SpanAttributes.HTTP_ROUTE], "^error/")
         self.assertEqual(span.attributes[SpanAttributes.HTTP_SCHEME], "http")
@@ -450,7 +450,7 @@ async def test_error_both_semconv(self):
         self.assertEqual(span.attributes[SpanAttributes.HTTP_METHOD], "GET")
         self.assertEqual(
             span.attributes[SpanAttributes.HTTP_URL],
-            "http://127.0.0.1/error/",
+            "http://testserver/error/",
         )
         self.assertEqual(span.attributes[SpanAttributes.HTTP_ROUTE], "^error/")
         self.assertEqual(span.attributes[SpanAttributes.HTTP_SCHEME], "http")