Utility method to sort a list of flavors.

    By default, returns the available flavors, sorted by RAM usage (ascending).
    Override these behaviours with a ``CREATE_INSTANCE_FLAVOR_SORT`` dict
    in ``local_settings.py``.

def sort_flavor_list(request, flavors, with_menu_label=True):
    """Utility method to sort a list of flavors.

    By default, returns the available flavors, sorted by RAM usage (ascending).
    Override these behaviours with a ``CREATE_INSTANCE_FLAVOR_SORT`` dict
    in ``local_settings.py``.
    """
    def get_key(flavor, sort_key):
        try:
            return getattr(flavor, sort_key)
        except AttributeError:
            LOG.warning('Could not find sort key "%s". Using the default '
                        '"ram" instead.', sort_key)
            return getattr(flavor, 'ram')
    try:
        flavor_sort = getattr(settings, 'CREATE_INSTANCE_FLAVOR_SORT', {})
        sort_key = flavor_sort.get('key', 'ram')
        rev = flavor_sort.get('reverse', False)
        if not callable(sort_key):
            def key(flavor):
                return get_key(flavor, sort_key)
        else:
            key = sort_key

        if with_menu_label:
            flavor_list = [(flavor.id, '%s' % flavor.name)
                           for flavor in sorted(flavors, key=key, reverse=rev)]
        else:
            flavor_list = sorted(flavors, key=key, reverse=rev)
        return flavor_list
    except Exception:
        exceptions.handle(request,
                          _('Unable to sort instance flavors.'))
        return []