def bound_addr(self):
        """The bind address.

        If it's an ephemeral port and the socket has been bound,
        return the actual port bound.
        """
        host, port = self.bind_addr
        if port == 0 and self.httpserver.socket:
            # Bound to ephemeral port. Get the actual port allocated.
            port = self.httpserver.socket.getsockname()[1]
        return host, port
The bind address.

        If it's an ephemeral port and the socket has been bound,
        return the actual port bound.
        
cherrypy/process/servers.py