Feature request: Fallback-URL for Helm Repositories

[MaxRink]

Use-case: we have an airgapped environment where we dont have an anycasted HA registry. We have two differnt registries, but if a need to take one down for maintenance everything pointing to that registry fails. On the container-level that mitigatiopn is happening on the containerd-level, asking the secondary mirror in case the primary is down. It would be nice to have the same thing with HelmRepositories e.g.

spec:
  url: https://charts.example.com
  fallback-url: https://mirror.example.com

or even

spec:
  url: https://charts.example.com
  fallback-urls: 
  - https://mirror.example.com
  - https://mirror2.example.com

[hiddeco]

This must be accepted as a Helm feature before we would consider integrating it in our controller, and given Helm is moving to the OCI format for charts, this is unlikely to ever happen.

I also do not see any big issues from the Helm registry being temporary down for maintenance, it will likely kick of some expected alerts because it temporary can not reached, and thereby halt chart related updates, but should automatically recover once the registry is up again.

[MaxRink]

yes, unless the helm chart actually comes from the same registry and you have a circular dependency :D