VNF AutoHealing triggered by FaultNotification

Overview

Tacker supports AutoHealing using FaultNotification interface. When fault events occur in VIM, VIM notifies fault event to Tacker via the interface. Tacker takes initiative of AutoHealing. Tacker checks faultID attribute in the fault event and determines whether AutoHealing should be performed. In case of performing AutoHealing, VMs are deleted or created.

Configuration

FaultNotification is disabled by default. To enable FaultNotification, be sure to set true for CONF.server_notification.server_notification.

Configuration

Default

Description

CONF.server_notification.server_notification

false

Enable FaultNotification interface.

CONF.server_notification.uri_path_prefix

/server_notification

Uri path prefix string for FaultNotification interface. When changing this configuration, server_notification description in api-paste.ini must be changed to the same value.

CONF.server_notification.timer_interval

20

When multiple fault events for a vnf instance are notified in the timer_interval seconds, Tacker packs these notifications into single event. By doing this, Tacker can avoid making too many healing request.

System

FaultNotification AutoHealing needs external service called Server Notifier.

The Server Notifier is a monitoring service that is implemented by each operators, thus it is not included in Tacker. When the Server Notifier detects fault events in VIM, it will send FaultNotification to Tacker.

Setting FaultNotification interface uri or enabling monitoring for the Server Notifier is performed along the vnf lifecycle. So Tacker provides a sample implementation of the mgmt driver script to achieve interface registration and enabling monitoring.

                       +--------------------------+
                       |      Client (NFVO)       +--------+
                       +--------------------------+        | 1. Vnf instantiation
                       +-----------------------------------v--------------------------------+
                       |               2.Create VM                                   Tacker |
6.FaultNotification    |               3.Interface registration (in mgmt driver)            |
        +-------------->               7.Perform Healing                                    |
        |              |               8.Delete failed VM and Create new VM                 |
        |              +---------------------------------------+-------------+--------------+
        |       +----------------------------------------------+             |
 +------|-------|------------------------------------------------------------|--------------+
 |      |       | 4.Start monitoring                +---------------+--------+     VIM/NFVI |
 |      |       |                                   |               |                       |
 |   +--+-------v--+                       +--------v----+   +------v------+                |
 |   | Server      | 5.Detects fault event | +--------+  |   | +--------+  |                |
 |   | Notifier    +-------------------------> VNF    |  |   | | VNF    |  |                |
 |   |             |                       | +--------+  |   | +--------+  |                |
 |   |             |                       |          VM |   |          VM |                |
 |   +-------------+                       +-------------+   +-------------+                |
 +------------------------------------------------------------------------------------------+

For details about the interface, please refer to [1].

Mgmt driver script

Sample mgmt driver script to achieve interface registration and enabling monitoring is tacker/sol_refactored/mgmt_drivers/server_notification.py

Put this script into target VNF package and Server Notifier can detect fault event on the VNF.

LCM interface

The LCM interface is modified to set parameters for Server Notifier. The additionalParams must be set when using FaultNotification.

  • Name: Instantiate VNF task
    Description: This task resource represents the Instantiate VNF operation. The client can use this resource to instantiate a VNF instance. Only the additionalParams for FaultNotification are described here.
    Method type: POST
    URL for the resource: /vnflcm/v2/vnf_instances/ {vnfInstanceId}/instantiate
    Request:

    Attribute name (InstantiateVnfRequest)

    Data type

    Cardinality

    Description

    additionalParams

    0..1

    KeyValuePairs (inlined)

    Additional input parameters for the instantiation process, specific to the VNF being instantiated.

    >ServerNotifierUri

    1

    String

    Base Uri for ServerNotifier.

    >ServerNotifierFaultID

    1..N

    String

    List of string that indicates which type of alarms to detect.

The value of ServerNotifierUri and ServerNotifierFaultID are stored in instantiatedVnfInfo of vnfInstance. The values can be shown with vnflcm show command. For example:

$ openstack vnflcm show 6fd264ea-78fb-4862-90c0-1a9597734d95 --os-tacker-api-version 2
+-----------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Field                       | Value                                                                                                                                                                |
+-----------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| ID                          | 6fd264ea-78fb-4862-90c0-1a9597734d95                                                                                                                                 |
| Instantiated Vnf Info       | {                                                                                                                                                                    |
|                             |  ....                                                                                                                                                                |
|                             |     "metadata": {                                                                                                                                                    |
|                             |         "ServerNotifierUri": "http://localhost:9990/server_notification",                                                                                            |
|                             |         "ServerNotifierFaultID": "1234"                                                                                                                              |
|                             |     }                                                                                                                                                                |
|                             |  ....                                                                                                                                                                |
+-----------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+

Auto Healing

When fault events occur in VIM, ServerNotifier notifies fault event to Tacker via the FaultNotification interface.

Tacker checks fault_id attribute in the fault event and determines whether AutoHealing should be performed. In case of performing AutoHealing, VMs are deleted and created via Heat. The client is no need to handle healing.

References