[3.8] Custom error message for Unix connect errors (#4985) (#5264)

* Custom error message for Unix connect errors

* Update aiohttp/client_exceptions.py

Co-authored-by: Sviatoslav Sydorenko <[email protected]>

Co-authored-by: Andrew Svetlov <[email protected]>
Co-authored-by: Sviatoslav Sydorenko <[email protected]>.
(cherry picked from commit e19c79e)

Co-authored-by: Zeal Wierslee <[email protected]>

Co-authored-by: Zeal Wierslee <[email protected]>

CHANGES/4984.bugfix

@@ -0,0 +1 @@
+Added a new exception type for Unix socket client errors which provides a more useful error message.

CONTRIBUTORS.txt

@@ -308,6 +308,8 @@ Young-Ho Cha
 Yuriy Shatrov
 Yury Selivanov
 Yusuke Tsutsumi
+Yuval Ofir
+Zeal Wierslee
 Zlatan Sičanica
 Марк Коренберг
 Семён Марьясин

aiohttp/client_exceptions.py

@@ -195,6 +195,29 @@ class ClientProxyConnectionError(ClientConnectorError):
     """
 
 
+class UnixClientConnectorError(ClientConnectorError):
+    """Unix connector error.
+
+    Raised in :py:class:`aiohttp.connector.UnixConnector`
+    if connection to unix socket can not be established.
+    """
+
+    def __init__(
+        self, path: str, connection_key: ConnectionKey, os_error: OSError
+    ) -> None:
+        self._path = path
+        super().__init__(connection_key, os_error)
+
+    @property
+    def path(self) -> str:
+        return self._path
+
+    def __str__(self) -> str:
+        return "Cannot connect to unix socket {0.path} ssl:{1} [{2}]".format(
+            self, self.ssl if self.ssl is not None else "default", self.strerror
+        )
+
+
 class ServerConnectionError(ClientConnectionError):
     """Server connection errors."""
 

aiohttp/connector.py

@@ -39,6 +39,7 @@
     ClientHttpProxyError,
     ClientProxyConnectionError,
     ServerFingerprintMismatch,
+    UnixClientConnectorError,
     cert_errors,
     ssl_errors,
 )
@@ -1194,7 +1195,7 @@ async def _create_connection(
                     self._factory, self._path
                 )
         except OSError as exc:
-            raise ClientConnectorError(req.connection_key, exc) from exc
+            raise UnixClientConnectorError(self.path, req.connection_key, exc) from exc
 
         return cast(ResponseHandler, proto)
 

docs/client_reference.rst

@@ -2105,6 +2105,10 @@ Connection errors
 
    Derived from :exc:`ClientConnectorError`
 
+.. class:: UnixClientConnectorError
+
+   Derived from :exc:`ClientConnectorError`
+
 .. class:: ServerConnectionError
 
    Derived from :exc:`ClientConnectionError`