problem on get_attribute function

[philippemerle]

Following is a simplified version of an ETSI NFV SOL001 example:

tosca_definitions_version: tosca_simple_yaml_1_3
node_types:
  tosca.nodes.nfv.VNF:
    attributes:
      scale_status:
        type: map
        entry_schema:
          type: integer
  MyCompany.SunshineDB.1_0.1_0:
    derived_from: tosca.nodes.nfv.VNF
    attributes:
      call_proc_scale_level:
        type: integer
topology_template:
  node_templates:
    SunshineDB:
      type: MyCompany.SunshineDB.1_0.1_0
      attributes:
        call_proc_scale_level: { get_attribute: [ SELF, scale_status, call_proc ] }

Compiling this template with puccini 0.21.1 produces a problem:

$ puccini-tosca compile --coerce example.yaml 
PROBLEMS (1)
  file:/.../example.yaml 
    @20,9 topology_template.node_templates["SunshineDB"].attributes["call_proc_scale_level"]: call to tosca.function.get_attribute("SELF","scale_status","call_proc") failed because nested attribute "scale_status.call_proc" not found in "SunshineDB"

scale_status is a declared attribute of SunshineDB node template, and is a map with string keys and integer entries.

Until the execution, it is impossible to check that the scale_status map contains the call_proc key.

But a TOSCA parser should only check that call_proc is of type string (else this is a typing error) and that the type of the get_attribute expression (here integer) is compatible with the type of the assigned attribute (here integer), else this is a typing error. So we could expect that this template should not be rejected by any TOSCA parser/compiler.

Am I missing something on this example?

[tliron]

The issue is your use of --coerce: it indeed tries to call all functions, and it's indeed a problem with attributes that do not have default values. This is by design, and it's the reason that --coerce is not the default.

Attributes are out of the scope of Puccini itself, as it's just a frontend for TOSCA. A complete system could work like this:

1. Use puccini-tosca compile to create a Clout (no --coerce)
2. A system will update the Clout attributes with values
3. You can call puccini-clout scriptlet exec tosca.coerce on the Clout, whenever you want, to see all current values

(It is also possible for a system to incorporate Puccini as a library and manage Clout in a different way. The puccini-clout tool is not the only way. Even more: a system does not have have to use Puccini for this. Because all the functions are written in JavaScript, it may be possible to support Clout with a different implementation other than Puccini.)

[tliron]

By the way, this is discussed in the tutorial in this and the following section. Please provide feedback if you think the description is not clear enough!

[philippemerle]

Thank you for your explanation.