kustomization.yaml with no resources fails

[makkes]

Given this kustomization file in a directory pointed to by a Flux Kustomization:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources: []

The Kustomization fails with this error:

$ k -n flux-system get kustomization k
NAME   READY   STATUS   AGE
k      False   apply failed: error: no objects passed to apply
       39s

which makes sense because there are no resources to apply but I wonder whether a check should be added to kustomize-controller to see whether the set of resources is actually empty and immediately go into ready state. Happy to discuss.

[JaneLiuL]

Good issue~
I think we should change the message like:"apply finish: no objects passed to apply"
I would like to take this issue.

label //good first issue

[stefanprodan]

I’m not for changing this behavior, if we really want to set an empty kustomization to ready then we need to wait a couple of months for GA, as this is a major break change in behavior.

[smurfralf]

This is actually a bug. If I have a kustomization that has resources, then I remove them resulting in an empty kustomization, then instead of the controller reconcile deleting the resources, it gives the "apply failed: error: no objects passed to apply". If an object has been removed, it should be deleted by flux. So while this error behavior may make sense for a kustomization that is first set up (basically saying "hey! why did you set up an empty kustomization / folder?") it is not correct after a kustomization has created resources then had them removed.

[makkes]

I agree it's a bug, especially since kustomize itself doesn't fail with an empty resources list. However, I see @stefanprodan's point that it's a breaking change if all of a sudden an empty resources list doesn't result in a Ready: false condition, anymore because people out there might already rely on that behaviour.

[smurfralf]

I wouldn't object to the Ready:false status if the reconcile would first delete the resources that have been removed.

[takirala]

I am also affected by this. At the least, we can fix the "bug" such that the prune is correctly honored. Right now, when all the resources are truncated (resources: []) after having a non zero length, kustomize-controller fails to prune them correctly. We don't have to make a change of behavior on Ready: false, but we can fix the behavior to prune the resources correctly.