Add Synapse-Trace-Id to access-control-expose-headers header

changelog.d/14974.misc

@@ -0,0 +1 @@
+Add `Synapse-Trace-Id` to `access-control-allow-headers` header.

synapse/http/server.py

@@ -900,7 +900,7 @@ def set_cors_headers(request: SynapseRequest) -> None:
     else:
         request.setHeader(
             b"Access-Control-Allow-Headers",
-            b"X-Requested-With, Content-Type, Authorization, Date",
+            b"X-Requested-With, Content-Type, Authorization, Date, Synapse-Trace-Id",
         )
 
 

tests/test_server.py

@@ -263,7 +263,7 @@ def _check_cors_standard_headers(self, channel: FakeChannel) -> None:
         )
         self.assertEqual(
             channel.headers.getRawHeaders(b"Access-Control-Allow-Headers"),
-            [b"X-Requested-With, Content-Type, Authorization, Date"],
+            [b"X-Requested-With, Content-Type, Authorization, Date, Synapse-Trace-Id"],
             "has correct CORS Headers header",
         )