Construct an HTTP client for this container.

def http_client(self, port=None):
        """
        Construct an HTTP client for this container.
        """
        # Local import to avoid potential circularity.
        from seaworthy.client import ContainerHttpClient
        client = ContainerHttpClient.for_container(self, container_port=port)
        self._http_clients.append(client)
        return client