assigning a value expression to the default of a property/parameter/attribute definition is not allowed by TOSCA

[philippemerle]

The TOSCA 1.3 grammar allows one to assign a default value to a property/attribute/parameter definition, see Sections 3.6.10.4, 3.6.12.3, and 3.6.14.2. But I found no assigment of a default value expression such as a concat/join/token/get_property/get_attribute/... function call in the TOSCA 1.3 specification. Conceptually, the default value of a property/attribute/parameter definition is a simple (or complex) constant such as 1, true, hello, 10 s, 20 Hz, [ 1, 2, 3 ], { x: 10, y: 20 }, ...

However, I found around 300 assigments of a default value expression across all xOpera examples.
For this finding and all my previous issues, I found them automatically with our TOSCA toolbox.

Is it an expected specific xOpera feature or a misinterpretation of the TOSCA specification?

[anzoman]

@philippemerle ok, so according to TOSCA for instance default: { get_property: [ SELF, my_property ] } is not a valid default value assignment because we're using get_property TOSCA function, which is a value expression? If this is the case then we probably have a misinterpretation of the TOSCA specification here.

Also thanks for linking your TOSCA toolbox, we'll take a look.

[philippemerle]

according to TOSCA for instance default: { get_property: [ SELF, my_property ] } is not a valid default value assignment because we're using get_property TOSCA function, which is a value expression?

yes this is not a valid default value assignment because { get_property: [ SELF, my_property ] } is an expression.

[philippemerle]

I started to correct this on xopera-opera : see xlab-si/xopera-opera#225 and philippemerle/xopera-opera@fb20330

[anzoman]

Great @philippemerle, thanks for fixing this.

[philippemerle]

I corrected all the errors related to default assignments (see #49) except for two default assignments in tosca/intrinsic-functions/service.yaml:

  hello_type_3:
    derived_from: tosca.nodes.SoftwareComponent
    attributes:
      attribute3_2:
        type: string
        default: { join: [ [ "a", "t", "t", "r", "i", "b", "u", "t", "e" ] ] } # ERROR 1
    properties:
      property3_2:
        type: string
        default: { concat: [ 'Property: ', get_attribute: [ SELF, attribute3_2 ] ] } # ERROR 2

Here, default could not be replaced by value because value is not a valid keyname for both attribute and property definitions in TOSCA 1.3. You should revisit the design/implementation of this example to correct these two errors.

Just for information, TOSCA 2.0 makes value a valid keyname for both attribute and property definitions.

[philippemerle]

@anzoman perhaps this issue should be reopened as there are still 2 errors in tosca/intrinsic-functions/service.yaml.

[anzoman]

Aha ok, I'm reopening this.