fix(aiohttp): Preserve SigV4-signed propagation headers

- collect headers that must not be modified in `headers_to_skip`.
- preserve existing `sentry-trace` headers to avoid replacing the current trace context.
- leave signed `sentry-trace` and `baggage` headers untouched; missing propagation headers are added.
- tests added for signed, unsigned and presigned requests.

Resolves #7426

Co-authored-by: Pablo Deputter <pablo.deputter@sentry.io>

Author: Robinbinu

sentry_sdk/consts.py

@@ -7,6 +7,8 @@
 DEFAULT_MAX_STACK_FRAMES = 100
 DEFAULT_ADD_FULL_STACK = False
 
+_SENTRY_HEADER_NAMES = frozenset(("baggage", "sentry-trace"))
+
 
 # Also needs to be at the top to prevent circular import
 class EndpointType(Enum):

sentry_sdk/integrations/aiohttp.py

@@ -4,7 +4,7 @@
 
 import sentry_sdk
 from sentry_sdk.api import continue_trace
-from sentry_sdk.consts import OP, SPANDATA, SPANSTATUS
+from sentry_sdk.consts import _SENTRY_HEADER_NAMES, OP, SPANDATA, SPANSTATUS
 from sentry_sdk.data_collection import (
     _apply_data_collection_filtering_to_query_string,
 )
@@ -29,6 +29,7 @@
 )
 from sentry_sdk.tracing import (
     BAGGAGE_HEADER_NAME,
+    SENTRY_TRACE_HEADER_NAME,
     SOURCE_FOR_STYLE,
     TransactionSource,
 )
@@ -43,6 +44,8 @@
     HAS_REAL_CONTEXTVARS,
     SENSITIVE_DATA_SUBSTITUTE,
     AnnotatedValue,
+    _get_aws_sigv4_signed_headers_from_authorization_header,
+    _get_aws_sigv4_signed_headers_from_url_query_string,
     _register_control_flow_exception,
     capture_internal_exceptions,
     ensure_integration_enabled,
@@ -464,12 +467,50 @@ async def on_request_start(
             span = legacy_span
 
         if should_propagate_trace(client, str(params.url)):
+            # existing `sentry-trace`: skip so it is not duplicated.
+            headers_to_skip: "set[str]" = set()
+            if SENTRY_TRACE_HEADER_NAME in params.headers:
+                headers_to_skip.add(SENTRY_TRACE_HEADER_NAME)
+
+            with capture_internal_exceptions():
+                authorization = params.headers.get("Authorization")
+                if authorization:
+                    if isinstance(authorization, bytes):
+                        authorization = authorization.decode("latin-1")
+                    # `SignedHeaders` lists fields covered by SigV4.
+                    signed_headers = (
+                        _get_aws_sigv4_signed_headers_from_authorization_header(
+                            authorization
+                        )
+                    )
+                    # skip signed `sentry-trace` and `baggage`.
+                    headers_to_skip.update(
+                        _SENTRY_HEADER_NAMES.intersection(signed_headers)
+                    )
+
+                # presigned URLs list signed names in the query string.
+                query_signed_headers = (
+                    _get_aws_sigv4_signed_headers_from_url_query_string(str(params.url))
+                )
+                headers_to_skip.update(
+                    _SENTRY_HEADER_NAMES.intersection(query_signed_headers)
+                )
+
             for (
                 key,
                 value,
             ) in sentry_sdk.get_current_scope().iter_trace_propagation_headers(
                 span=span
             ):
+                # skip signed headers and an existing `sentry-trace`.
+                if key.lower() in headers_to_skip:
+                    logger.debug(
+                        "[Tracing] Not adding `{key}` header to outgoing request "
+                        "to {url}: it already exists or is covered by the AWS "
+                        "SigV4 signature.".format(key=key, url=params.url)
+                    )
+                    continue
+
                 logger.debug(
                     "[Tracing] Adding `{key}` header {value} to outgoing request to {url}.".format(
                         key=key, value=value, url=params.url

sentry_sdk/integrations/stdlib.py

@@ -6,11 +6,11 @@
 from typing import TYPE_CHECKING
 
 import sentry_sdk
-from sentry_sdk.consts import OP, SPANDATA
+from sentry_sdk.consts import _SENTRY_HEADER_NAMES, OP, SPANDATA
 from sentry_sdk.integrations import Integration
 from sentry_sdk.scope import add_global_event_processor
 from sentry_sdk.traces import StreamedSpan
-from sentry_sdk.tracing import BAGGAGE_HEADER_NAME, SENTRY_TRACE_HEADER_NAME, Span
+from sentry_sdk.tracing import SENTRY_TRACE_HEADER_NAME, Span
 from sentry_sdk.tracing_utils import (
     EnvironHeaders,
     add_http_breadcrumb,
@@ -42,9 +42,6 @@
     "version": "%s.%s.%s" % (sys.version_info[:3]),
     "build": sys.version,
 }
-
-_SENTRY_HEADER_NAMES = frozenset((BAGGAGE_HEADER_NAME, SENTRY_TRACE_HEADER_NAME))
-
 try:
     from botocore.awsrequest import AWSHTTPConnection, AWSHTTPSConnection
 except ImportError:

tests/integrations/aiohttp/test_aiohttp.py

@@ -875,7 +875,9 @@ async def handler(request):
 
 
 @pytest.mark.asyncio
-async def test_outgoing_trace_headers(sentry_init, aiohttp_raw_server, aiohttp_client):
+async def test_outgoing_trace_headers_adds_missing_unsigned_propagation_headers(
+    sentry_init, aiohttp_raw_server, aiohttp_client
+):
     sentry_init(
         integrations=[AioHttpIntegration()],
         traces_sample_rate=1.0,
@@ -903,10 +905,11 @@ async def handler(request):
             parent_span_id=request_span.span_id,
             sampled=1,
         )
+        assert resp.request_info.headers["baggage"].count("sentry-trace_id=") == 1
 
 
 @pytest.mark.asyncio
-async def test_outgoing_trace_headers_append_to_baggage(
+async def test_outgoing_trace_headers_appends_baggage_but_preserves_sentry_trace(
     sentry_init, aiohttp_raw_server, aiohttp_client
 ):
     sentry_init(
@@ -927,12 +930,94 @@ async def handler(request):
             trace_id="0123456789012345678901234567890",
         ):
             client = await aiohttp_client(raw_server)
-            resp = await client.get("/", headers={"bagGage": "custom=value"})
+            resp = await client.get(
+                "/",
+                headers={
+                    "bagGage": "custom=value",
+                    "Sentry-Trace": "existing-trace",
+                },
+            )
 
             assert (
                 resp.request_info.headers["baggage"]
                 == "custom=value,sentry-trace_id=0123456789012345678901234567890,sentry-sample_rand=0.500000,sentry-environment=production,sentry-release=d08ebdb9309e1b004c6f52202de58a09c2268e42,sentry-transaction=/interactions/other-dogs/new-dog,sentry-sample_rate=1.0,sentry-sampled=true"
             )
+            # existing `sentry-trace`: leave as-is.
+            assert resp.request_info.headers["sentry-trace"] == "existing-trace"
+
+
+@pytest.mark.asyncio
+async def test_outgoing_trace_headers_preserves_signed_propagation_headers(
+    sentry_init, aiohttp_raw_server, aiohttp_client
+):
+    sentry_init(
+        integrations=[AioHttpIntegration()],
+        traces_sample_rate=1.0,
+    )
+
+    async def handler(request):
+        return web.Response(text="OK")
+
+    raw_server = await aiohttp_raw_server(handler)
+    # both propagation headers are named in `SignedHeaders`.
+    authorization = (
+        "AWS4-HMAC-SHA256 "
+        "Credential=test/20260804/eu-west-1/secretsmanager/aws4_request, "
+        "SignedHeaders=baggage;host;sentry-trace, "
+        "Signature=sixtyseven"
+    )
+
+    with start_transaction(name="test", sampled=True):
+        client = await aiohttp_client(raw_server)
+        resp = await client.get(
+            "/",
+            headers={
+                "baggage": "vendor=value",
+                "sentry-trace": "existing-trace",
+                "Authorization": authorization,
+            },
+        )
+
+    headers = resp.request_info.headers
+    # signed `baggage`: leave as-is.
+    assert headers["baggage"] == "vendor=value"
+    # signed `sentry-trace`: leave as-is.
+    assert headers["sentry-trace"] == "existing-trace"
+
+
+@pytest.mark.asyncio
+async def test_outgoing_trace_headers_preserves_query_signed_baggage(
+    sentry_init, aiohttp_raw_server, aiohttp_client
+):
+    sentry_init(
+        integrations=[AioHttpIntegration()],
+        traces_sample_rate=1.0,
+    )
+
+    async def handler(request):
+        return web.Response(text="OK")
+
+    raw_server = await aiohttp_raw_server(handler)
+    path = (
+        "/"
+        "?X-Amz-Algorithm=AWS4-HMAC-SHA256"
+        "&X-Amz-Credential="
+        "test%2F20260804%2Feu-west-1%2Fs3%2Faws4_request"
+        "&X-Amz-Date=20260804T120000Z"
+        "&X-Amz-Expires=60"
+        "&X-Amz-SignedHeaders=baggage%3Bhost"
+        "&X-Amz-Signature=sixtyseven"
+    )
+
+    with start_transaction(name="test", sampled=True):
+        client = await aiohttp_client(raw_server)
+        resp = await client.get(path, headers={"baggage": "vendor=value"})
+
+    headers = resp.request_info.headers
+    # query-signed `baggage`: leave as-is.
+    assert headers["baggage"] == "vendor=value"
+    # unsigned `sentry-trace`: add it.
+    assert "sentry-trace" in headers
 
 
 @pytest.mark.asyncio