2nd iteration fix socket activation

server.py

@@ -47,29 +47,30 @@ from middleware.cache_middleware import cache_control
 # Helper --------------------------------------------------------------------
 def _fd_to_socket(fd: int) -> socket.socket:
     """
-    Turn a raw file‑descriptor that came from systemd into a *non‑blocking*
+    Convert a file‑descriptor received from systemd into a ready‑to‑use
-    ``socket.socket`` instance that preserves the original family, type and
+    ``socket.socket`` object.
-    protocol.
 
-    The function mirrors the logic used by `sd_listen_fds` in the systemd
+    * The fd already contains the correct address family, socket type and
-    libraries (see libsystemd/libsystemd/sd-daemon.c).  It queries the
+      protocol – passing ``fileno=fd`` makes the constructor adopt them.
-    kernel for the socket's actual family, type and protocol using
+    * aiohttp (and the rest of the code) expects the socket to be **non‑blocking**,
-    ``getsockopt`` on the fd.
+      so we set that flag explicitly.
+    * Any OSError while wrapping the descriptor is turned into a RuntimeError
+      with a clear message; the caller can log it.
     """
-    # Query the kernel for the family / type / protocol of the fd.
+    try:
-    # These syscalls are cheap and work for IPv4, IPv6 and Unix sockets.
+        # ``socket.socket`` with the ``fileno`` argument re‑uses the existing OS
-    family = socket.getsockopt(fd, socket.SOL_SOCKET, socket.SO_DOMAIN)
+        # socket.  The resulting object automatically reports the correct
-    sock_type = socket.getsockopt(fd, socket.SOL_SOCKET, socket.SO_TYPE)
+        # ``family``, ``type`` and ``proto`` attributes.
-    proto = socket.getsockopt(fd, socket.SOL_SOCKET, socket.SO_PROTOCOL)
+        sock = socket.socket(fileno=fd)
 
-    # Build the socket object *without* creating a new fd.
+        # aiohttp’s SockSite registers the socket with the event loop, which
-    # ``socket.socket`` with ``fileno=fd`` re‑uses the existing descriptor.
+        # requires a non‑blocking descriptor.
-    # ``closefd=False`` tells Python not to close the fd when the socket
+        sock.setblocking(False)
-    # object is garbage‑collected – systemd will close it when the service
+
-    # exits.
+        return sock
-    sock = socket.socket(family=family, type=sock_type, proto=proto, fileno=fd)
+    except OSError as exc:
-    sock.setblocking(False)               # aiohttp expects non‑blocking
+        # Raising a RuntimeError makes the caller’s ``except`` clause simpler.
-    return sock
+        raise RuntimeError(f"Could not wrap fd {fd} as a socket: {exc}") from exc
 
 async def send_socket_catch_exception(function, message):
     try: