Why does a Tekton resource cannot contain a dot?

[goldmann]

I see this validation being enforced on Tekton resources:

pipeline/pkg/apis/validate/metadata.go

Lines 31 to 36 in 879ba4f

	if strings.Contains(name, ".") {
	return &apis.FieldError{
	Message: "Invalid resource name: special character . must not be present",
	Paths: []string{"name"},
	}
	}

A dot is a a perfectly valid character within the resource name as per Kubernetes docs. Why Tekton does not allow for dots in resource names?

Dots are generally very useful, for example in cases where you would like to have versions as part of the name.

[vdemeester]

/kind feature

If it's valid for kubernetes, I don't see why we block this indeed. Looking at https://github.com/tektoncd/pipeline/blame/0cb2bf09f1a2ebc30e833d3e64a38b61858be51c/pkg/apis/pipeline/v1alpha1/metadata_validation.go, seems like it's been there since the start of the project (as part of the skeleton).

/cc @tektoncd/core-maintainers

[imjasonh]

It goes back even further, to Knative Build days. Digging even further, this check seems to show up for the first time in knative/build#181, written by a rather untrustworthy looking character named @imjasonh 🤔

I agree with @vdemeester that this is probably unnecessary and can be removed so .s are allowed.

[psschwei]

/assign @psschwei