...
- Modeling team accepts multiple node template instances in service template (To support which means to provide the List type of inputs so that multiple sets of inputs can be supported in one service template)
Note:
1）TOSCA TOSCA service templates specify a set of nodes that need to be created at service deployment time. Some service templates may include multiple nodes that perform the same role. For example, a template that models an SD-WAN service might contain multiple VPN Site nodes, one for each location that accesses the SD-WAN. Rather than having to create a separate service template for each possible number of VPN sites, it would be preferable to have a single service template that allows the number of VPN sites to be specified at deployment time.
2) According to our discussion with Tosca team, the List type of inputs is also one of the needs of TOSCA 1.2.
(Anatoly Katzman Hui Deng Andy Mayer shitao li ) - SDC supports multiple node design of List inputs in TOSCA service template (Ofir Sonsino )
1) On Design interface List type of resources can be provided
2) Tosca parser supports parsing of List type of inputs
3) Database supports store List type of inputs - SO support List input interface(Seshu Kumar Mudiganti )
The ideal solution should be that a CCVPN service can be instantiated by using one service template and customers can decide the number of resources when creating a service.
TOSCA working group also pays attention to this problem and they came up with an improved service templates which can satisfy our needs:
...
Keyname
...
Required
...
Type
...
Constraints
...
Description
...
occurrences
...
no
...
range of integer
...
when not specified, defaults to [1,1]
...
The optional minimum and maximum number of instances that can be created from this node template. If not specified, only one single instance can be created.
...
instance_count
...
no
...
integer
...
when not specified, defaults to the lower bound of the range specified by the ‘occurrences’ keyname
To satisfy this needs, an optimization on service template– List type of inputs should be supported
The requested number of runtime instance of the node template.
Specifying Inputs
The service template in the previous section conveniently ignores the location property of the Site node. As shown earlier, the location property is expected to be provided as an input value. If Site node templates can be instantiated multiple times, then it follows that multiple input values are required to initialize the location property for each of the Site node instances.
To allow specific input values to be matched with specific node template instances, a new reserved keyword is introduced:
...
Keyword
...
Valid Contexts
...
Description
...
INDEX
...
Node Template
...
A TOSCA orchestrator will interpret this keyword as the runtime index in the list of node instances created from a single Node Template.
The following service template shows how the INDEX keyword is used to retrieve specific values from a list of input values in a service template:
tosca_definitions_version: tosca_simple_yaml_1_2
description: Template for deploying SD-WAN with a variable number of sites.
topology_template:
inputs:
numberOfSites:
type: integer
locations:(VNF)
type: list
entry_schema: Location
node_templates:
sdwan:
type: VPN
site:
type: VPNSite
occurrences: [1, UNBOUNDED]
instance_count: { get_input: numberOfSites }
properties:
location: { get_input: [ locations, INDEX ] }
requirements:
...
see Reference:
1, TOSCA Enhancements to Support Multiple Node Template Instances
...