'Load a control service certificate and key from the supplied path.
:param FilePath path: Directory where control service certificate
and key files are stored.
:param bytes hostname: The hostname of the control service certificate.'

@classmethod
def from_path(cls, path, hostname):

    (keypair, certificate) = load_certificate_from_path(path, 'control-{}.key'.format(hostname), 'control-{}.crt'.format(hostname))
    credential = FlockerCredential(path=path, keypair=keypair, certificate=certificate)
    return cls(credential=credential)
