Only log if an existing localpart was found, extend logged info

changelog.d/8773.misc

@@ -0,0 +1 @@
+Minor log line improvements for the SSO mapping code used to generate Matrix IDs from SSO IDs.

synapse/handlers/saml_handler.py

@@ -268,7 +268,8 @@ async def _map_saml_response_to_user(
                 user_id = UserID(
                     map_username_to_mxid_localpart(attrval), self.server_name
                 ).to_string()
-                logger.info(
+
+                logger.debug(
                     "Looking for existing account based on mapped %s %s",
                     self._grandfathered_mxid_source_attribute,
                     user_id,
@@ -324,7 +325,7 @@ async def _map_saml_response_to_user(
             if contains_invalid_mxid_characters(localpart):
                 raise MappingException("localpart is invalid: %s" % (localpart,))
 
-            logger.info("Mapped SAML user to local part %s", localpart)
+            logger.debug("Mapped SAML user to local part %s", localpart)
             registered_user_id = await self._registration_handler.register_user(
                 localpart=localpart,
                 default_display_name=displayname,

synapse/handlers/sso.py

@@ -71,19 +71,25 @@ async def get_sso_user_by_remote_user_id(
         Returns:
             The mxid of a previously seen user.
         """
-        # Check if we already have a mapping for this user.
-        logger.info(
+        logger.debug(
             "Looking for existing mapping for user %s:%s",
             auth_provider_id,
             remote_user_id,
         )
+
+        # Check if we already have a mapping for this user.
         previously_registered_user_id = await self.store.get_user_by_external_id(
             auth_provider_id, remote_user_id,
         )
 
         # A match was found, return the user ID.
         if previously_registered_user_id is not None:
-            logger.info("Found existing mapping %s", previously_registered_user_id)
+            logger.info(
+                "Found existing mapping for IdP '%s' and remote_user_id '%s': %s",
+                auth_provider_id,
+                remote_user_id,
+                previously_registered_user_id,
+            )
             return previously_registered_user_id
 
         # No match.