def _make_component_meta(builder):
    """
    Return a dict of selected builder attributes to save in composite meta. The
    dict has keys ``version``, ``replicas`` and ``id``.
    :param builder: a :class:`swift.common.ring.builder.RingBuilder`
        instance
    :return: a dict of component metadata
    """
    attrs = ['version', 'replicas', 'id']
    metadata = dict((attr, getattr(builder, attr)) for attr in attrs)
    return metadata