chore: add debug logging for token length and expiry

Author: enocom

google/cloud/alloydbconnector/connector.py

@@ -259,6 +259,7 @@ async def connect_async(self, instance_uri: str, driver: str, **kwargs: Any) ->
         try:
             metadata_partial = partial(
                 self.metadata_exchange,
+                instance_uri,
                 ip_address,
                 await conn_info.create_ssl_context(),
                 enable_iam_auth,
@@ -272,7 +273,11 @@ async def connect_async(self, instance_uri: str, driver: str, **kwargs: Any) ->
             raise
 
     def metadata_exchange(
-        self, ip_address: str, ctx: ssl.SSLContext, enable_iam_auth: bool
+        self,
+        instance_uri: str,
+        ip_address: str,
+        ctx: ssl.SSLContext,
+        enable_iam_auth: bool,
     ) -> ssl.SSLSocket:
         """
         Sends metadata about the connection prior to the database
@@ -318,6 +323,12 @@ def metadata_exchange(
         if not self._db_credentials.token_state == TokenState.FRESH:
             self._db_credentials.refresh(requests.Request())
 
+        logger.debug(
+            f"['{instance_uri}']: OAuth2 token used for metadata exchange has "
+            f"expiration={self._credentials.expiry}, "
+            f"size={len(self._credentials.token)}"
+        )
+
         # form metadata exchange request
         req = connectorspb.MetadataExchangeRequest(
             user_agent=f"{self._client._user_agent}",  # type: ignore