fix(httpx): Prevent Sentry baggage duplication

sentry_sdk/integrations/httpx.py

@@ -2,7 +2,7 @@
 from sentry_sdk.consts import OP, SPANDATA
 from sentry_sdk.integrations import Integration, DidNotEnable
 from sentry_sdk.tracing import BAGGAGE_HEADER_NAME
-from sentry_sdk.tracing_utils import should_propagate_trace
+from sentry_sdk.tracing_utils import Baggage, should_propagate_trace
 from sentry_sdk.utils import (
     SENSITIVE_DATA_SUBSTITUTE,
     capture_internal_exceptions,
@@ -14,6 +14,7 @@
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
+    from collections.abc import MutableMapping
     from typing import Any
 
 
@@ -76,11 +77,9 @@ def send(self, request, **kwargs):
                             key=key, value=value, url=request.url
                         )
                     )
-                    if key == BAGGAGE_HEADER_NAME and request.headers.get(
-                        BAGGAGE_HEADER_NAME
-                    ):
-                        # do not overwrite any existing baggage, just append to it
-                        request.headers[key] += "," + value
+
+                    if key == BAGGAGE_HEADER_NAME:
+                        _add_sentry_baggage_to_headers(request.headers, value)
                     else:
                         request.headers[key] = value
 
@@ -148,3 +147,21 @@ async def send(self, request, **kwargs):
             return rv
 
     AsyncClient.send = send
+
+
+def _add_sentry_baggage_to_headers(headers, sentry_baggage):
+    # type: (MutableMapping[str, str], str) -> None
+    """Add the Sentry baggage to the headers.
+
+    This function directly mutates the provided headers. The provided sentry_baggage
+    is appended to the existing baggage. If the baggage already contains Sentry items,
+    they are stripped out first.
+    """
+    existing_baggage = headers.get(BAGGAGE_HEADER_NAME, "")
+    stripped_existing_baggage = Baggage.strip_sentry_baggage(existing_baggage)
+
+    separator = "," if len(stripped_existing_baggage) > 0 else ""
+
+    headers[BAGGAGE_HEADER_NAME] = (
+        stripped_existing_baggage + separator + sentry_baggage
+    )

sentry_sdk/tracing_utils.py

@@ -609,6 +609,21 @@ def serialize(self, include_third_party=False):
 
         return ",".join(items)
 
+    @staticmethod
+    def strip_sentry_baggage(header):
+        # type: (str) -> str
+        """Remove Sentry baggage from the given header.
+
+        Given a Baggage header, return a new Baggage header with all Sentry baggage items removed.
+        """
+        return ",".join(
+            (
+                item
+                for item in header.split(",")
+                if not Baggage.SENTRY_PREFIX_REGEX.match(item.strip())
+            )
+        )
+
 
 def should_propagate_trace(client, url):
     # type: (sentry_sdk.client.BaseClient, str) -> bool

tests/test_tracing_utils.py

@@ -1,7 +1,7 @@
 from dataclasses import asdict, dataclass
 from typing import Optional, List
 
-from sentry_sdk.tracing_utils import _should_be_included
+from sentry_sdk.tracing_utils import _should_be_included, Baggage
 import pytest
 
 
@@ -94,3 +94,24 @@ def test_should_be_included(test_case, expected):
     kwargs = asdict(test_case)
     kwargs.pop("id")
     assert _should_be_included(**kwargs) == expected
+
+
+@pytest.mark.parametrize(
+    ("header", "expected"),
+    (
+        ("", ""),
+        ("foo=bar", "foo=bar"),
+        (" foo=bar, baz =  qux ", " foo=bar, baz =  qux "),
+        ("sentry-trace_id=123", ""),
+        ("  sentry-trace_id = 123  ", ""),
+        ("sentry-trace_id=123,sentry-public_key=456", ""),
+        ("foo=bar,sentry-trace_id=123", "foo=bar"),
+        ("foo=bar,sentry-trace_id=123,baz=qux", "foo=bar,baz=qux"),
+        (
+            "foo=bar,sentry-trace_id=123,baz=qux,sentry-public_key=456",
+            "foo=bar,baz=qux",
+        ),
+    ),
+)
+def test_strip_sentry_baggage(header, expected):
+    assert Baggage.strip_sentry_baggage(header) == expected