Support messageExpression in CRD validation rules

[pmalek]

Problem statement

Currently, kubebuilder supports rule and message fields when specifying +kubebuilder:validation:XValidation.

Kubernetes 1.25 introduced CRD validation rules (beta0 which also allow specifying messageExpression.

The following is now possible when specifying CRD validations:

x-kubernetes-validations:
- rule: "self.x <= self.maxLimit"
  messageExpression: '"x exceeded max limit of " + string(self.maxLimit)'

Unfortunately kubebuilder doesn't support this:

unknown argument "messageExpression" (at <input>:1:117)

This issue tracks the proposal and implementation of support for messageExpression in // +kubebuilder:validation:XValidation.

https://book.kubebuilder.io/reference/markers/crd-validation.html

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle rotten
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten

[JoelSpeed]

/remove-lifecycle rotten

We should definitely be implementing this support

[pmalek]

I'd be willing to contribute a patch for this if someone provided guidance what would be needed.

[sbueringer]

@pmalek I think you can start from here:

controller-tools/pkg/crd/markers/validation.go

Line 311 in 5c4990c

type XValidation struct {

and then try to implement it analog to Rule and/or Message

(also grep for rule/message in the repo in general and see if there are relevant occurences)

Apologies for the fuzzy guidance but that's literally all I know without diving a lot deeper into it :)

[pmalek]

Thanks @sbueringer 🙇

I've pushed #927 with an attempt to provide support for messageExpression. Thanks for guidance.

[pmalek]

/assign