Hi,
I’d like to ask how we could enable Buildkit for docker and more specificially docker-compose builds (we use docker-compose plugin).
If you don’t, that would turn into a feature request :) We have an unconventional docker multistage setup which doesn’t cache well with the regular docker engine (more than 1 base build), and there are improvements we’d like to take advantage of with the new engine, which seems to support that.
Agreed, this would be a great feature! I opened https://github.com/buildkite-plugins/docker-compose-buildkite-plugin/issues/256 a while back too 
The two main features I’d love to see in the docker-compose plugin are support for passing --ssh in the build (currently available in Buildkit but not docker-compose itself I believe), and being able to specify a target to build/push for multi-stage builds to help with caching like your case.