openstack/tacker-specs
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VNF Workflows Customization by Action Driver

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ETSI NFV doesn't define Lifecycle Management (LCM) workflow behaviors.
Currently, Tacker has a default LCM workflow, VNF vendors can't change
the default workflow. The default workflow doesn't satisfy some
VNF's LCM requirements.

We want to enable VNF vendor to customize their workflows
by Action Driver.

Change-Id: I49dce1bc2bfded9f69fdea1c1a48636af59d1f8b
Blueprint: action-driver
This commit is contained in:
Toshiaki Takahashi 2020-07-14 13:11:40 +09:00
parent 96f0c20269
commit 8e0097cb79
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This work is licensed under a Creative Commons Attribution 3.0 Unported
License.
http://creativecommons.org/licenses/by/3.0/legalcode
============================================
VNF Workflows Customization by Action Driver
============================================
Problem description
===================
ETSI NFV doesn't define Lifecycle Management (LCM) workflow behaviors.
Currently, Tacker has a default LCM workflow, VNF vendors can't change the default workflow.
The default workflow doesn't satisfy some VNF's LCM requirements.
* For healing, evacuation is used instead of deletion and creation.
We want to enable VNF vendor to customize their workflows by Action Driver.
Proposed change
===============
This proposal suggests providing the Action Driver function to flexibly choose
customized LCM workflows. Expanding Tacker's ability is best accomplished with
a driver model similar to the existing Management and Infrastructure Drivers.
Currently, Mgmt Driver function configures applications provided by VNF vendors.
So we should also enable VNF vendors to customize configuration methods
for applications via Mgmt Driver.
These customizations are specified by "interface" definition in
ETSI NFV-SOL001 [#NFV-SOL001]_ "6.7 Interface Types".
Overview of Action Driver function is as follows
(Concrete non-standard driver implementations are future works.
Only import Python implementation drivers is the first scope.):
::
+------------------+ interface of Lifecycle
| | +-----------------+ +-----------------+ +----------------+
| | | | | | | |
| VNFM API +------->+ VNF Lifecycle +-----+-->+ Action Driver +---------->+ Infra Driver |
| | | Management | | | | | |
| | | | | | +-+ | +-+
| | +-----------------+ | +-+---------------+ | +-+--------------+ |
+------------------+ | | [standard] | | OpenStack_T |
| | Instantiate | | OpenStack_V |
| | Heal_evacuate | | Kubernetes_3 |
| | Heal_recreate | | : |
| | | +----------------+
| | [custom] |
| | Heal_evacuate |
| | |
| | [mistral WF] |
| | (Future work) |
| | Instantiate_ |
| | VNF_A |
| | Instantiate_ |
| | VNF_B |
| | |
| +-----------------+
|
| +----------------+
+---->+ |
interface of | Mgmt Driver |
Lifecycle start/end | |
(xxx_start/xxx_end) | +-+
+-+--------------+ |
| Ansible |
| cloud+init |
| Kubernetes |
| : |
+----------------+
Flow of instantiation of a VNF instance with Action Driver is as follows:
::
+----------+ +---------------+ +-----------+ +---------------+ +--------------+
| | | | | | | | | |
| VNFM API | | VNF Lifecycle | | Tacker DB | | Action Driver | | Mgmt Driver |
| | | Management | | | | | | |
| | | | | | | | | |
+----+-----+ +------+--------+ +-----+-----+ +-------+-------+ +------+-------+
| | | | |
| Instantiate VNF | | | |
+------------------> | | |
<- - - - - - - - - + Fetch action | | |
| (async) | from vnfd_dict | | |
| | | | |
| +-------------------> | |
| <-------------------+ | |
| | | | |
| | | | |
| | mgmt_call( | | |
| | method='instantiate_start') | |
| | | | |
| +----------------------------------------------------------->|
| <------------------------------------------------------------+
| | | | |
| | | | |
| | action_call( | | |
| | method='action_instantiate_vnf') | |
| | | | |
| +---------------------------------------> +------+ |
| | | | |Infra | |
| | | | |Driver| |
| | | | +---+--+ |
| | | | | |
| | | | | |
| | | | instantiate_vnf |
| | | | | |
| | | +---------> |
| | | <---------+ |
| <---------------------------------------+ | |
| | | | + |
| | | | |
| | mgmt_call( | | |
| | method='instantiate_end') | |
| | | | |
| +----------------------------------------------------------->|
| <------------------------------------------------------------+
| | | | |
| | | | |
+ + + + +
How to Define the Drivers
-------------------------
Action Driver and Mgmt Driver are specified by VNFD.
How to specify Action Driver is as follows:
::
node_templates:
VNF:
type: tacker.sample.VNF
properties:
flavour_description: A simple flavour
interfaces:
Vnflcm:
instantiate:
implementation: action-drivers-custom
.
.
.
artifacts:
action-drivers-custom:
description: Action driver standard
type: tosca.artifacts.Implementation.Python
file: /usr/local/lib/python3.6/site-packages/tacker/vnfm/action_drivers/custom_action_driver_1.py
How to specify Mgmt Driver is as follows:
::
node_templates:
VNF:
type: tacker.sample.VNF
properties:
flavour_description: A simple flavour
interfaces:
Vnflcm:
instantiate: []
instantiate_start:
implementation: mgmt-drivers-noop
instantiate_end:
implementation: mgmt-drivers-custom
terminate: []
terminate_start: []
terminate_end: []
artifacts:
mgmt-drivers-custom:
description: Management driver custom
type: tosca.artifacts.Implementation.Python
file: /usr/local/lib/python3.6/site-packages/tacker/vnfm/mgmt_drivers/custom_mgmt.py
artifacts:
mgmt-drivers-noop:
description: Management driver noop
type: tosca.artifacts.Implementation.Python
file: /usr/local/lib/python3.6/site-packages/tacker/vnfm/mgmt_drivers/noop.py
In the case that we use artifacts in VNF package,
we write relative path as the value of 'file:' in 'artifacts:' block.
The following is the default VNFD description
which specify all driver implementations as standard.
i.e. We can customize the following implementations.
::
interfaces:
Vnflcm:
instantiate: []
instantiate_start: []
instantiate_end: []
terminate: []
terminate_start: []
terminate_end: []
heal: []
heal_start: []
heal_end: []
scale: []
scale_start: []
scale_end: []
Action Driver Directories Structure
-----------------------------------
This spec proposes the creation of a "action_drivers" under tacker/vnfm.
::
tacker
|-- plugin.py
|-- vnfm
|-- action_drivers
|-- abstract_driver.py
|-- custom_action_driver_1.py
|-- custom_action_driver_2.py
:
Alternatives
------------
None
Data model impact
-----------------
None
REST API impact
---------------
None
Security impact
---------------
None
Notifications impact
--------------------
None
Other end user impact
---------------------
Users can specify LCM action and pre/post setting with VNFD.
Performance impact
------------------
None
Other deployer impact
---------------------
None
Developer impact
----------------
None
Implementations
===============
Assignee(s)
-----------
Primary assignee:
1. Toshiaki Takahashi
Work Items
----------
* Action Driver main process
* Cooperation with existing Mgmt Driver Framework
* Calling Action Driver process from LCM process
* VNFD reading and Action Driver setting
* Unit tests
* Functional tests
Dependencies
============
Testing
=======
Unit and functional tests are sufficient to test specified process
written in VNFD is called correctly.
Documentation Impact
====================
* Add document about how to customize LCM with Action Driver
References
==========
.. [#NFV-SOL001] https://www.etsi.org/deliver/etsi_gs/NFV-SOL/001_099/001/02.06.01_60/gs_NFV-SOL001v020601p.pdf