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.. Modifications Copyright © 2017-2018 AT&T Intellectual Property.
.. Licensed under the Creative Commons License, Attribution 4.0 Intl.
(the "License"); you may not use this documentation except in compliance
with the License. You may obtain a copy of the License at
.. https://creativecommons.org/licenses/by/4.0/
.. Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
Manual Scale Out Use Case
=========================
.. contents:: Table of Contents
:depth: 4
:backlinks: entry
Overview
--------
In the Casablanca release, ONAP will support the ability to both manually and
automatically scale out a VNF component. Below is the sequence diagram
for how scaling will work.
Design Time Diagram
^^^^^^^^^^^^^^^^^^^
.. uml::
:align: center
:caption: **Scale Out Sequence Diagram** - Design Time
@startuml
title Message Style - Scale Out Sequence Diagram - Design Time
skinparam sequenceMessageAlign center
Participant "Service Designer" as SD
Participant SDC
Participant CLAMP
Participant CDT
Participant APPC
Participant SDNC
Participant Policy
Participant SO
Participant DCAE
SD -> SDC: <back:white>Onboarding Package</back>
SD -> SDC: <back:white>Set Scaling Parameters</back>
SDC -> SO: <back:white>Send Heat Templates and Image Files</back>
SDC -> SDNC: <back:white>Send Heat Templates and Image Files</back>
SDC -> SDNC: <back:white>Send Preload files</back>
SDC -> DCAE: <back:white>Threshold Scaling Events</back>
SD -> CLAMP: <back:white>Gaurd Policies</back>
SD -> CLAMP: <back:white>Operational Policies</back>
SD -> CLAMP: <back:white>Configuration Data</back>
CLAMP -> Policy: <back:white>Send Policies to Policy Engine Including VNF Configuration Data and VF_Module Name</back>
SD -> CDT: <back:white>Parameter definition template for each LCM action (ConfigScaleOut, Healthcheck)</back>
CDT -> APPC: <back:white>Save Parameter Definition Template to APPC</back>
@enduml
Run Time Diagram
^^^^^^^^^^^^^^^^
.. uml::
:align: center
:caption: **Scaling Use Case Sequence Diagram** - Run Time
@startuml
title Message Style - Scaling Use Case Sequence Diagram - Run Time
skinparam sequenceMessageAlign center
Participant DCAE
Participant Policy
Participant VID
Participant SO
Participant Controller
Participant SDNC
Participant AAI
Participant VNF
group Manual Scaling
VID -> SO: Manual Scale Out Request\n(Via DMaaP)
end
group Closed Loop Scaling
DCAE -> Policy: Trigger Scale Out Event
activate Policy
|||
Policy -> Policy: Sanity Check (Guard Policies)
|||
Policy -> SO: <back:white>Closed Loop Scale Out Request</back>
deactivate Policy
activate SO
end
group Healthcheck
SO -> AAI: <back:white>Retrieve VNF Level ipv4-oam-address</back>
note left
Prerequisite: Heatbridge will update
AAI with all IP addresses on initial
instantiation
end note
AAI -> SO: <back:white>Return VNF Level ipv4-oam-address</back>
|||
SO -> SO: Controller Look up
activate Controller
SO -> Controller: Healthcheck
Controller -> VNF: Healthcheck (REST)
deactivate Controller
end
group Instantiation
SO -> AAI: Create VF-Module in AAI
note left
Homing and Capacity is
not shown in this
diagram. If H&C check is
done then SO will call
OOF prior to calling
SDNC for resource
assignment.
end note
activate AAI
deactivate AAI
SO -> SDNC: <back:white>VF-Module Resource Assignment</back>
activate SDNC
SDNC -> SDNC: Heat & Resource Assignment
|||
SDNC -> AAI: Create VF-Module Relationship & Retrieve Networks
deactivate SDNC
SO -> VNF: <back:white>Create VF_Module in Cloud environment via Heatstack</back>
note left
SO will call the Rainy Day
Handling and/or Manual
Handling building blocks
whenever it detects a
failure in the WorkFlow
end note
SO -> AAI: Update the Heatstack ID
end
group Configuration
SO -> SDNC: <back:white>Request Configuration Parameter Values</back>
SDNC -> SO: <back:white>Return Configuration Parameter Values</back>
|||
SO -> SO: Build ConfigScaleOut Payload
SO -> SO: Contoller Look up
SO -> Controller: ConfigScaleOut
activate Controller
Controller -> Controller: Construct VNF ScaleOut Request
Controller -> VNF: Configure VNF (Netconf)
deactivate Controller
end
group Healthcheck
SO -> AAI: <back:white>Retrieve VNF Level ipv4-oam-address</back>
AAI -> SO: <back:white>Return VNF Level ipv4-oam-address</back>
|||
SO -> SO: Controller Look up
activate Controller
SO -> Controller: Healthcheck
Controller -> VNF: Healthcheck (REST)
deactivate Controller
deactivate SO
end
@enduml
Description of Workflow
-----------------------
At a high level the way Scale Out will work is:
1. ``VF_Modules`` (VNFC’s) may be scaled out with either one of two methods:
a. Using VID, the operator will choose to scale out a VNFC by picking
a ``VF_Module`` to scale
b. An operator may define an operating policy (and associated guard
policies) to trigger a scaling operation automatically.
* As an example, the operating policy may be when the output of an
application load balancer crosses a bandwidth threshold, then increase
the number of instances of the application.
* Examples of a guard policies:
1. If a scaling operation has run within the past X minutes, then do
not scale.
2. If the number of instance is <= ``MIN_INSTANCES``
or >= ``MAX_INSTANCES``, then do not scale.
2. VID or Policy sends the Scale Out Request to SO.
3. When SO receives the Scaling request it will first send a request to the
appropriate controller (APPC or SDNC) to execute a health check on the VNF.
4. Once the health check has been run, SO executes the Heat Template associated
with the VF Module requested by the VID Operator or the operational policy.
5. After the new component(s) have been instantiated SO calls the responsible
controller (via DMaaP) to configure the new instances using Ansible, Chef,
or Netconf.
6. Finally a health check is run to ensure that the entire VNF is Operating
as it should.
VNF Impacts
-----------
For VNFs to make use of the Manual Scaling Capabilities of ONAP, they must
support the following functionality:
1. VNFs must support a Healthcheck as described in:
:ref:`onap_management_requirements`.
a. R-41430 is the requirement dictating the need for VNF Healthchecks.
b. The health check may be supported using REST, Ansible, or Chef
* REST health check requirements can be found in the :ref:`xnf_rest_apis`
* The Ansible health check playbook can be found in the :ref:`ansible_playbook_requirements`
2. R-43413 states that a "VNF MUST utilize a modular Heat Orchestration
Template design to support scaling". The description of this design may
be found in the :ref:`heat_onap_vnf_modularity_overview`
of the Heat Requirements.
a. The ``VF_Module`` to be scaled must be built according to the VNF
Modularity Rules for Incremental Modules
3. Configuration of the VNF must be done via NETCONF, Chef, or Ansible as
described in the :ref:`vnf_configuration_management`
|
