Allow SemVer Helm Chart Version from OCI Registry

[rowi1de]

• For Git based you are able to point an Application to a branch or ref

  source:
    repoURL:  https://github.com/rowi1de/graphql-reactive
    targetRevision:  HEAD

• ArgoCD will always deploy the latest commit / revision

• For Helm on OCI you need to specify a fixed Version of the Helm Chart in the Application

 project: my-helm-chart
 source:
   repoURL: ghcr.io/rowi1de/graphql-reactive
   targetRevision:  0.0.17

• For Classic Helm Registries you can use SemVer ranges: https://argo-cd.readthedocs.io/en/stable/user-guide/tracking_strategies/

  project: my-helm-chart
  source:
    repoURL: ghcr.io/rowi1de/graphql-reactive
    targetRevision: 0.0.*

• This doesn't work for Helm on OCI, as ArgoCD expect Index.yaml which is only available for classic helm repositories.

  argo-cd/reposerver/repository/repository.go

  Line 1663 in 7faae31

  index, err := helmClient.GetIndex(noRevisionCache)

• OCI doesn't allow discovering versions, but it can list tags: https://github.com/opencontainers/distribution-spec/blob/main/spec.md#content-discovery
• Also for helm pull, version ranges are supported
• The error in ArgoCD is Unable to deploy revision: rpc error: code = Unknown desc = Get "ghcr.io/rowi1de/graphql-reactive/graphql-reactive/index.yaml": unsupported protocol scheme ""

helm pull oci://ghcr.io/rowi1de/graphql-reactive/graphql-reactive --version '0.0.*'
Pulled: ghcr.io/rowi1de/graphql-reactive/graphql-reactive:0.0.17

helm pull oci://ghcr.io/rowi1de/graphql-reactive/graphql-reactive --version '0.1.*'
Pulled: ghcr.io/rowi1de/graphql-reactive/graphql-reactive:0.1.2

• My workflow is as follows

  • CI with GitHub Actions
    • Tag & Push Docker Image with commit-id
    • Increment Patch Version of the Helm Chart based on SemVer
    • Publish new Helm Chart to Github Packages as OCI Image
    • Point Argo CD to the OCI Image / Helm Chart

• One Note: I'm currently not pushing the modified Chart.yaml from the GitHub Action Release workflow, so the committed Chart.yaml will always contain a wrong version

[fe-ax]

Not sure if this is what you mean, but Argo already supports tracking versions: https://argo-cd.readthedocs.io/en/stable/user-guide/tracking_strategies/

[dpiraud]

Ok we found out OCI doesn't support listing versions, BUT if you remove the version it would pull latest:

shell
helm pull oci://ghcr.io/rowi1de/graphql-reactive/graphql-reactive

This could be used

It does not work with version like x.x.x-x. For this kind of version, I have to use de --devel flag like so

`
helm pull --debug oci://registry.xxx... --devel

pull.go:63: [debug] setting version to >0.0.0-0
...
`

Doing this in debug mode, you'll see that version is set to >0.0.0-0, that's why i use it in #9447 because argo manifest needs a non empty version

I think you point the problem with the cache mamagment and it explain the "hard refresh trick" of my discussion.

[rowi1de]

@dpiraud the Problem is also there if you leave out the „pre-release“ syntax e.g.
only 0.0.x won’t work due to missing search/list of versions in OCI.

Seems like OCI supports listing tags, but Helm has not implemented that https://github.com/opencontainers/distribution-spec/blob/main/spec.md#content-discovery

helm/helm#11000

[rowi1de]

So I was digging around a bit more: Helm does support version ranges for helm pull:

helm pull oci://ghcr.io/rowi1de/graphql-reactive/graphql-reactive --version '0.0.*'
Pulled: ghcr.io/rowi1de/graphql-reactive/graphql-reactive:0.0.17


helm pull oci://ghcr.io/rowi1de/graphql-reactive/graphql-reactive --version '0.1.*'
Pulled: ghcr.io/rowi1de/graphql-reactive/graphql-reactive:0.1.2

This means argoCD could support helm version ranges for OCI

[rumstead]

Are we using this issue to track - #6686?

[rowi1de]

I’m not a maintainer.
I think there are more recent answers in the issues you mentioned #6686 (comment)