fix(outlook): retry LDAP user searches with fresh connections

app/connectors_service/connectors/sources/outlook/client.py

@@ -145,8 +145,7 @@ def __init__(
         self.ssl_enabled = ssl_enabled
         self.ssl_ca = ssl_ca
 
-    @cached_property
-    def _create_connection(self):
+    def _create_ldap_connection(self):
         return Connection(
             server=self.ad_server,
             user=self.user,
@@ -155,47 +154,51 @@ def _create_connection(self):
             auto_bind=True,  # pyright: ignore
         )
 
-    async def close(self):
-        pass
-
-    def _fetch_normal_users(self, search_query):
+    @retryable(
+        retries=RETRIES,
+        interval=RETRY_INTERVAL,
+        strategy=RetryStrategy.EXPONENTIAL_BACKOFF,
+        skipped_exceptions=[UsersFetchFailed],
+    )
+    def _ldap_search(self, search_query, search_filter):
+        connection = self._create_ldap_connection()
         try:
-            has_value_for_normal_users, _, response, _ = self._create_connection.search(
+            has_value, _, response, _ = connection.search(
                 search_query,
-                SEARCH_FILTER_FOR_NORMAL_USERS,
+                search_filter,
                 attributes=["mail"],
             )
 
-            if not has_value_for_normal_users:
+            if not has_value:
                 msg = "Error while fetching users from Exchange Active Directory."
                 raise UsersFetchFailed(msg)
 
-            for user in response:
-                yield user
+            return response
+        finally:
+            try:
+                connection.unbind()
+            except Exception as exc:
+                logger.debug("Failed to unbind LDAP connection: %s", exc)
 
+    async def close(self):
+        pass
+
+    def _fetch_normal_users(self, search_query):
+        try:
+            for user in self._ldap_search(search_query, SEARCH_FILTER_FOR_NORMAL_USERS):
+                yield user
+        except UsersFetchFailed:
+            raise
         except Exception as e:
             msg = f"Something went wrong while fetching users. Error: {e}"
             raise UsersFetchFailed(msg) from e
 
     def _fetch_admin_users(self, search_query):
         try:
-            (
-                has_value_for_admin_users,
-                _,
-                response_for_admin,
-                _,
-            ) = self._create_connection.search(
-                search_query,
-                SEARCH_FILTER_FOR_ADMIN,
-                attributes=["mail"],
-            )
-
-            if not has_value_for_admin_users:
-                msg = "Error while fetching users from Exchange Active Directory."
-                raise UsersFetchFailed(msg)
-
-            for user in response_for_admin:
+            for user in self._ldap_search(search_query, SEARCH_FILTER_FOR_ADMIN):
                 yield user
+        except UsersFetchFailed:
+            raise
         except Exception as e:
             msg = f"Something went wrong while fetching users. Error: {e}"
             raise UsersFetchFailed(msg) from e

app/connectors_service/tests/sources/test_outlook.py

@@ -732,6 +732,66 @@ async def test_fetch_admin_users(mock_connection):
         assert users == ["test.user@gmail.com", "dummy.user@gmail.com"]
 
 
+@patch("connectors.utils.time_to_sleep_between_retries", return_value=0)
+@patch("connectors.sources.outlook.client.Connection")
+def test_ldap_search_retries_on_transient_error(mock_connection, _mock_sleep):
+    mock_connection_instance = mock_connection.return_value
+    mock_connection_instance.search.side_effect = [
+        OSError("Connection reset by peer"),
+        (True, None, ["user@example.com"], None),
+    ]
+
+    exchange_users = ExchangeUsers(
+        ad_server="ad.example.com",
+        domain="example.com",
+        exchange_server="exchange.example.com",
+        user="user",
+        password="password",
+        ssl_enabled=False,
+        ssl_ca=None,
+    )
+    response = exchange_users._ldap_search("search_query", "filter")
+    assert list(response) == ["user@example.com"]
+    assert mock_connection.call_count == 2
+    assert mock_connection_instance.search.call_count == 2
+    assert mock_connection_instance.unbind.call_count == 2
+
+
+@patch("connectors.sources.outlook.client.Connection")
+def test_exchange_ldap_search_uses_fresh_connection_per_search(mock_connection):
+    normal_user = {"mail": "normal@example.com"}
+    admin_user = {"mail": "admin@example.com"}
+
+    first_connection = MagicMock()
+    first_connection.search.return_value = (True, None, [normal_user], None)
+    second_connection = MagicMock()
+    second_connection.search.return_value = (True, None, [admin_user], None)
+    mock_connection.side_effect = [first_connection, second_connection]
+
+    exchange_users = ExchangeUsers(
+        ad_server="ad.example.com",
+        domain="example.com",
+        exchange_server="exchange.example.com",
+        user="user",
+        password="password",
+        ssl_enabled=False,
+        ssl_ca=None,
+    )
+
+    users = asyncio.run(_collect_exchange_users(exchange_users))
+    assert users == [normal_user, admin_user]
+    assert mock_connection.call_count == 2
+    first_connection.search.assert_called_once()
+    second_connection.search.assert_called_once()
+
+
+async def _collect_exchange_users(exchange_users):
+    users = []
+    async for user in exchange_users.get_users():
+        users.append(user)
+    return users
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     "attachment, expected_content",