tacker-specs/specs/victoria/support-etsi-nfv-based-errorhandling.rst

Support ETSI NFV-SOL based error-handling

https://blueprints.launchpad.net/tacker/+spec/support-etsi-nfv-specs

ETSI specifications within the NFV Architecture Framework¹ describe the main aspects of NFV development and usage based on of the industry needs, feedback from SDN/NFV vendors and telecom operators. These specifications include the REST API and data model architecture which is used by NFV users and developers in related products.

Problem description

In the current Tacker implementation based on ETSI NFV-SOL, Tacker executes its own error-handling operation which reacts to errors the VNFM encounters.

However, those operations are not aligned with the current ETSI NFV data-model. As a result, there might be lack of compatibility with 3rd party VNFs², as they are developed according to ETSI NFV specifications. Support of key ETSI NFV specifications will significantly reduce efforts for Tacker integration into Telecom production networks and also will simplify further development and support of future standards.

Proposed change

Introduces a new interface to VNFM for reverting VNF lifecycle management operations for VNF instances. The operation provided through this interface is:

• Rollback

1) Flow of Rollback of LCM resource

Precondition: The operation state should be set in "FAILED_TEMP" state. Moreover, ongoing lifecycle management operation should be either VNF instantiation or Scaling-out.

The procedure consists of the following steps as illustrated in each sections.

1-1) Sending of Notification

• VNFM holds the Callback URL sent by consumer via "Subscription API" in advance.
• Depending on the progress status of the lifecycle management operations, send API notification (Notify) to notify the status change and update the internal operation_status.
• The node that received the notification returns 204 NO CONTENT indicating success and grasps the sequence status of VNFM.

The states that VNFM notifies with VNF Rollback are as follows:

• ROLLING_BACK
• ROLLED_BACK

Postcondition: When the rollback operation is completed successfully, the operation state will be changed in "ROLLEDBACK" state.

1-2) Rollback LCM operation

When a Rollback request is received, VNFM operates to stop the lifecycle operation normally while it is terminated. When the rollback operation is executed during VNF instantiation, VNFM removes all VMs and resources.

seqdiag {

node_width = 105; edge_length = 130;

Client -> "tacker-server"

[label = "POST /vnf_lcm_op_occs/{vnfLcmOpOccId}/rollback"];

Client <-- "tacker-server" [label = "Response 202 Accepted"]; "tacker-server" -> "tacker-conductor" [label = "trriger asynchronous task"]; "tacker-conductor" ->> "tacker-conductor" [label = "execute notification process"]; Client <- "tacker-conductor" [label = "POST {callback URI} (ROLLING_BACK)"]; Client --> "tacker-conductor" [label = "Response: 204 No Content"]; "tacker-conductor" -> "VnfLcmDriver" [label = "execute VnfLcmDriver"]; "VnfLcmDriver" -> "openstackDriver" [label = "execute openstackDriver"]; "openstackDriver" -> "heat" [label = "delete stack"]; "openstackDriver" <-- "heat" [label = ""]; "VnfLcmDriver" <-- "openstackDriver" [label = ""]; "tacker-conductor" <-- "VnfLcmDriver" [label = ""]; "tacker-conductor" ->> "tacker-conductor" [label = "execute notification process"]; Client <- "tacker-conductor" [label = "POST {callback URI} (ROLLED_BACK)"]; Client --> "tacker-conductor" [label = "Response: 204 No Content"];

}

When the rollback operation is executed for Scale-out, VNFM deletes all VMs and resources specified in the middle of Scale-out operation.

seqdiag {

node_width = 72; edge_length = 100;

Client -> "tacker-server"

[label = "POST /vnf_lcm_op_occs/{vnfLcmOpOccId}/rollback"];

Client <-- "tacker-server" [label = "Response 202 Accepted"]; "tacker-server" -> "tacker-conductor" [label = "trriger asynchronous task"]; "tacker-conductor" ->> "tacker-conductor" [label = "execute notification process"]; Client <- "tacker-conductor" [label = "POST {callback URI} (ROLLING_BACK)"]; Client --> "tacker-conductor" [label = "Response: 204 No Content"]; "tacker-conductor" -> "MgmtDriver" [label = "execute MgmtDriver"]; "MgmtDriver" -> vnf [label = "VNF Configuration"]; "MgmtDriver" <-- vnf [label = ""]; "tacker-conductor" <-- "MgmtDriver" [label = ""]; "tacker-conductor" -> "VnfLcmDriver" [label = "execute VnfLcmDriver"]; "VnfLcmDriver" -> "openstackDriver" [label = "execute openstackDriver"]; "openstackDriver" -> "heat" [label = "resourse signal"]; "openstackDriver" -> "heat" [label = "update stack"]; "openstackDriver" <-- "heat" [label = ""]; "VnfLcmDriver" <-- "openstackDriver" [label = ""]; "tacker-conductor" <-- "VnfLcmDriver" [label = ""]; "tacker-conductor" ->> "tacker-conductor" [label = "execute notification process"]; Client <- "tacker-conductor" [label = "POST {callback URI} (ROLLED_BACK)"]; Client --> "tacker-conductor" [label = "Response: 204 No Content"];

}

User needs to separately implement Rollback sub-operation by VNF Configuration. In case of Scale-out, VNFM starts VNF Configuration for rollbacking. Instantiation does not launch VNF Configutration.

Postcondition: When Rollback is successfully completed, the instantiation state has transited to NOT_INSTANTIATED state only for "Instantiate VNF".

Alternatives

None

Data model impact

None

REST API impact

The following RESTful API will be added. This RESTful API will be based on ETSI NFV SOL002 and SOL003³.

• Name: Rollback VNF oepration
  Description: Request to rollback VNF lifecycle operations
  Method type: POST
  URL for the resource: /vnflcm/v1/vnf_lcm_op_occs/{vnfLcmOpOccId}/rollback
  Request: Resource URI variables for this resource

  Name	Description
  vnfLcmOpOccId	Identifier of the related VNF lifecycle management operation occurrence.

  Response:

  Data type	Cardinality	Response Codes	Description
  n/a	n/a	Success 202 Error 404 409	The request has been accepted for processing, but processing has not been completed.

Security impact

None

Notifications impact

None

Other end user impact

Add new OSC commands in python-tackerclient to invoke rollback operation of VNF instances API.

Performance Impact

None

Other deployer impact

The previously created VNFs will not be allowed to be managed using the newly introduced APIs.

Developer impact

None

Implementation

Assignee(s)

Primary assignee:

Keiko Kuriu <keiko.kuriu.wa@hco.ntt.co.jp>

Work Items

• Add new REST API endpoints to Tacker-server for LCM notifications interface of VNF instances.
• Make changes in python-tackerclient to add new OSC commands for calling rollback operation of VNF instances RESTful APIs.
• Add features which Tacker consumes Rest API for Notifications
• Add new unit and functional tests.
• Change API Tacker documentation.

Dependencies

To execute rollback operations, consumer should invoke subscription operaiton ⁴ in advance in order to get "vnfLcmOpOccId" related to the target LCM operation.

Testing

Unit and functional test cases will be added for VNF lifecycle management of VNF instances.

Documentation Impact

Complete user guide will be added to explain how to invoke VNF lifecycle management of VNF instances with examples.

References

---

1. https://www.etsi.org/technologies-clusters/technologies/NFV↩︎

2. https://portal.etsi.org/Portals/0/TBpages/CTI/Docs/2nd_ETSI_NFV_Plugtests_Report_v1.0.0.pdf↩︎

3. https://www.etsi.org/deliver/etsi_gs/NFV-SOL/001_099/003/02.06.01_60/gs_nfv-sol003v020601p.pdf (Chapter 5: VNF Lifecycle Management interface)↩︎

4. https://review.opendev.org/#/c/731718/↩︎