Auto garbabe collection

[taoyouh]

Description

Although the REST API allows deleting a tag, it does not trigger garbage collection and cannot free up the space it used. It would be convenient if a garbage collection can be triggered when deleting a tag or at a predefined interval.

To allow auto garbage collection, we'll also need a global lock file to indicate a garbage collection is ongoing and the registry is read-only.

[milosgajdos]

This is an admirable ambition, but not achievable in high-volume environments. You can mark registry as read-only by config which is what a lot of providers do when they run GC