Allow RGD resources to reference instance status fields

[bschaatsbergen]

Closes #762

Currently we explicitly exclude schema.status fields from being referenced in CEL expressions on RGD resources. The getSchemaWithoutStatus function deletes the status property before validation, preventing schema.status.* references, as previously intended.

This does however block the ability to reference computed status values (like status.endpoint: ${service.status.loadBalancer.ingress[0].hostname}) in dependent resources, forcing users to duplicate expressions instead of implementing a cleaner dependency pattern.

This removes that restriction by renaming the function to getInstanceSchema and including schema.status alongside schema.spec and schema.metadata.

Quick question for the maintainers; what was the reasoning behind initially excluding the status fields? Understanding the background here would help me add more appropriate safeguards around including schema.status.

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[jakobmoellerdev]

Hey there! thanks for the contrib. Mainly the limitations we must consider are:

1. Status Objects are always optional and may or may not be present. Referencing should only be possible with optional value reference closures IMHO.
2. Status Objects were previously unstructured so to get a proper setup, you would also need to replace usage here

   kro/pkg/graph/builder.go

   Line 572 in 548e4db

   func buildStatusSchema(

I think if you manage to get rid of dynamic status value computation on top of your change, this will be more "complete". Otherwise your RGD creation will have the schema but your cluster based instance will still not use this

[bschaatsbergen]

Hey there! thanks for the contrib. Mainly the limitations we must consider are:

1. Status Objects are always optional and may or may not be present. Referencing should only be possible with optional value reference closures IMHO.
2. Status Objects were previously unstructured so to get a proper setup, you would also need to replace usage here

   kro/pkg/graph/builder.go

   Line 572 in 548e4db

   func buildStatusSchema(

I think if you manage to get rid of dynamic status value computation on top of your change, this will be more "complete". Otherwise your RGD creation will have the schema but your cluster based instance will still not use this

Thanks for the quick review, @jakobmoellerdev! Just to confirm my understanding; we should exclude status from required fields before type-checking the instance schema, so that CEL expressions in dependent resources can reference the instance’s status without validation errors when it’s still empty? Basically, clean up/unmark any status entry from the schema.Required list?

In b4128a9, I've ensured status fields remain optional before type-checking the instance schema.

[jakobmoellerdev]

Before I push you further into any direction and you potentially have a waste of time, I want to have a conceptual guidance of @a-hilaly here as he wrote the original status schemaless logic. Expect a bit of turnaround due to kubecon please.

My understanding is that rgd resources should be able to FILL instance status fields, but not the other way around. an instance should aggregate status and we didnt have good cases yet in which the other way would have made sense.

[a-hilaly]

/ok-to-test

[a-hilaly]

/ok-to-test

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[tjamet]

First, I agree that, conceptually, we must be able to bubble up the resources status to the RGD instance the same way we cascade parameters down.

It is true that this brings a complexity when the status does not exist yet, but I think it is manageable and worth the effort

[tjamet]

We also need tests to ensure that:

1. when the status field can't be resolved (i.e. vpc.status == nil) the instance can be reconciled without error
2. when the status field exists (i.e. vpc.status.vpcID = "vpc-xzy"), after reconcile, the instance has status status.vpcID: vpc-xyz`

[tjamet]

Would we gain readability on the intent using slices.DeleteFunc

Suggested change

	// Remove "status" from required fields if present
	required := make([]string, 0, len(s.Required))
	for _, field := range s.Required {
	if field != "status" {
	required = append(required, field)
	}
	}
	s.Required = required
	s.Required = slices.DeleteFunc(s.Required, func(e string){
	return e == "status"
	})