Is there any opinion if the new backend and / or syntax might be supported in Drone sometime in the future?
docker build is handled by plugins, would there be any change to Drone core? Or would this be a new plugin?
As far as I can see, this could be an option for the existing Docker plugin or rather a completely new Docker build plugin.
It is probably worth taking some time to figure out if there is enough additional value since Drone supports some of the new functionality already (e.g. directory caching).
On the other hand, BuildKit seems to be the future and will probably become Docker’s default backend someday. I anticipate more and more projects switching to BuildKit and the new Dockerfile syntax. So it might even make sense to replace some of Drone’s features with BuildKit functionality later on. But it is probably a bit too early to tell.