[BUG] OCI charts does not seem to work when using khelm as a KRM container function or EXEC plugin

[ellakk]

Describe the bug

Using the example (using version 0.35.0 instead of 0.27.0 as it seems unavailable) with Kustomize exec plugin or Kustomize KRM function i get the following error:

Running khelm 2.3.3 (helm 3.11.3)
Using repository "oci://public.ecr.aws/karpenter" (unauthenticated)
Downloading repository index of oci://public.ecr.aws/karpenter
khelm: load chart karpenter: looks like "oci://public.ecr.aws/karpenter" is not a valid chart repository or cannot be reached: object required

The cli does work however:

khelm template myreleasex oci://public.ecr.aws/karpenter/karpenter --version 0.35.0
Running khelm 2.3.3 (helm 3.11.3)
Downloading chart oci://public.ecr.aws/karpenter/karpenter 0.35.0 from repo 
Rendering chart karpenter 0.35.0 with name "myreleasex" and namespace "default"

To Reproduce
Steps to reproduce the behavior:

Exec:

1. Download the OCI example in this repository
2. Install the khelm Kustomize exec plugin
3. Run Kustomize with "kustomize build --enable-alpha-plugins --enable-exec --network ."

KRM:

1. Do step one from Exec.
2. Append the following to metadata in the generator.yaml in the example and do:

metadata:
  annotations:
    config.kubernetes.io/function: |
      container:
        image: mgoltzsche/khelm:latest
        network: true

3. Run Kustomize with "kustomize build --enable-alpha-plugins --enable-exec --network ."

Expected behavior
The chart should be inflated.

khelm version:
Running khelm 2.3.3 (helm 3.11.3)

Desktop (please complete the following information):

• OS: NixOS

Additional context

I've tried with other OCI charts than the one in the example directory and i can't get any to work.

[mgoltzsche]

Looks like I forgot to update the example when I changed the implementation to behave like the Helm CLI: accepting the OCI image URI in the chart field, not as repository.
I'll adjust the example and make an e2e test render it...

[mgoltzsche]

@ellakk Working more with OCI chart repositories, I realized that the OCI repository can be declared within the repository field of a dependency within the Chart.yaml file. Correspondingly I adjusted khelm and released it with v2.3.4.
For backward-compatibility you can still leave the repository field within the the kustomize plugin or kpt function config empty and specify the whole image name (prefixed with oci://) within the chart field.