FEATURE: Add support for layerinfo caching configuration

[iseyer]

Distribution(all versions, going back to 9 years ago) supports 3 options for layerinfo caching: redis, inmemory, and disabled (by not being set to either redis or inmemory).

Currently, however, harbor is hardcoded to redis.

Expose this option to the harbor helm chart, to allow for configurations where redis is not available to the registry.

[zyyw]

Thank you for contributing to Harbor! I am thinking whether we should make this configurable in the upstream (goharbor/harbor) first, then we can discuss about enabling this configuration in harbor-helm.

[iseyer]

Out of curiosity - what would that look like? Seems like distribution handles this natively with no change to harbor itself. At what other levels would you want layer caching?

[zyyw]

By upstream, I was thinking about configuring harbor.yml in goharbor/harbor so that it can be configurable not only in harbor-helm but also in harbor offline-installer (docker-compose).

Also Harbor GC relies on redis as well:

• https://github.com/goharbor/harbor/blob/main/src/jobservice/job/impl/gc/garbage_collection.go#L494

[iseyer]

In that case - do you think it is worth supporting anything but redis for layer caching? If Redis is a hard requirement and it should stay that way, this issue (& PR) can be trashed

[MinerYang]

Will close per above discussion.