OCI registry for Helm Charts

Intro

Please refer to <README.md>.

Helm charts OCI registry

The blocker for switching Helm Charts entirely to OCI is currently our artifact discovery process, which uses the index.yaml file, that is available in HTTP based Helm registries only. So, to get started, we have to switch our discovery process to OCI based one. Currently, we’re already uploading our build artifacts to both HTTP and OCI repos, so nothing is blocking implementation and a switch.

High level migration plan:

• prepare and deploy distribution cache instance, configure it for the upstream ACR registry
  • ensure monitoring and alerting
• switch our CI/CD pipelines to not tag dev build artifacts
  • we want to use retention policies for helm charts as well
• implement changes in the app-operator
  • use OCI discovery instead of index.yaml from HTTP registries
  • (optional) solve the problem of presenting only X (by default 5) most recent versions in the ACE CR
  • introduce a concept of primary and fall-back registry
• stop uploading charts into HTTP registries
• reconfigure app-operator to use the OCI cache as the primary registry and upstream ACR as fallback
• cleanup HTTP registries
• handle China as for images