def create_server_power_off_alarm(aodh_client, alarm_name, server_uuid):
    """Create an alarm which triggers when an instance powers off.

    :param aodh_client: Authenticated aodh v2 client
    :type aodh_client: aodhclient.v2.client.Client
    :param alarm_name: Name of alarm to delete
    :type alarm_name: str
    :param server_uuid: UUID of server to monitor
    :type server_uuid: str
    :returns: Dict of alarm data
    :rtype: {}
    """
    alarm_def = {
        'type': 'event',
        'name': alarm_name,
        'description': 'Instance powered OFF',
        'alarm_actions': ['log://'],
        'ok_actions': ['log://'],
        'insufficient_data_actions': ['log://'],
        'event_rule': {
            'event_type': 'compute.instance.power_off.*',
            'query': [{'field': 'traits.instance_id',
                       'op': 'eq',
                       'type': 'string',
                       'value': server_uuid}]}}
    return aodh_client.alarm.create(alarm_def)