feat(chainloop): add EVIDENCE material type

[jiparis]

This PR adds a new material type called EVIDENCE which inherits from ARTIFACT, but it's not meant to represent a main software artifact, but a secondary, stored in CAS, piece of material. A test report, or a generated custom bill of materials are good examples for this new type.

Closes #698

[javirln]

Since the EVIDENCE type cannot be set or should be set as output: true on the contract level, we could inform the operator by raising an error. On the crafting_schema_validation.go:

// ValidateEvidenceNotOutput validates that materials with type EVIDENCE are not marked as output
func (schema *CraftingSchema) ValidateEvidenceNotOutput() error {
	for _, m := range schema.Materials {
		if m.GetType() != CraftingSchema_Material_EVIDENCE {
			continue
		}

		if m.GetOutput() {
			return fmt.Errorf("material with name=%s and type EVIDENCE cannot be marked as output: true", m.Name)
		}
	}

	return nil
}

And then run the validation on the crafter.go.

Wdyt @jiparis @migmartri ??

[migmartri]

Since the EVIDENCE type cannot be set or should be set as output: true on the contract level, we could inform the operator by raising an error. On the crafting_schema_validation.go:

// ValidateEvidenceNotOutput validates that materials with type EVIDENCE are not marked as output
func (schema *CraftingSchema) ValidateEvidenceNotOutput() error {
	for _, m := range schema.Materials {
		if m.GetType() != CraftingSchema_Material_EVIDENCE {
			continue
		}

		if m.GetOutput() {
			return fmt.Errorf("material with name=%s and type EVIDENCE cannot be marked as output: true", m.Name)
		}
	}

	return nil
}

And then run the validation on the crafter.go.

Wdyt @jiparis @migmartri ??

I do not think that in crafter.go would be enough since we might have other clients creating contracts. because of that, it might make sense to implement it server side, either with custom code as you showed or built-in using a custom protovalidate rule.

[migmartri]

in any case, I am ok doing the validation in another patch, because note that we can not enable until this is in place #703

[javirln]

LGTM!

[migmartri]

Let's update also the readme file with the info about the new material type, it seems we only added it to the docs page

[migmartri]

Let's update also the readme file with the info about the new material type, it seems we only added it to the docs page

I've updated it :)