ITE-11 Feature Requests

[adityasaky]

This issue collects feature requests / suggestions for ITE-11.

Debug / error messages for attribute check failures

Proposed by @MarkLodato in https://github.com/in-toto/ITE/pull/50/files#r1344473474.

A raw list of CEL expressions might be a bit limiting. If something fails, it's difficult to present a clear error message of what went wrong. You might want to have a field for error messages. (Similarly, giving each an optional name might make it more readable.)

For example:

expectedAttributes:
  - name: builderId
    require: "predicate.runDetails.builder.id == 'https://example.com/myBuilder'"
    errorMessage: '"Unexpected builder.id: expected \"https://example.com/myBuilder\", got " + predicate.runDetails.builder.id'
  - name: repository
    require: "predicate.externalParameters.repository == '<expected value>'"
    errorMessage: '...'

Cross-step / predicate attribute checks

Proposed by @trishankatdatadog.

Right now, attribute checks are applied against the predicate / step they are specified for. The idea is to have checks that cut across a step or predicate.