I hadn't heard of Buildpacks before, sounds very interesting.

In particular the out of order layer replacement. I'm interested in switching to Buildpack for the images I maintain for my home cluster. Would make upgrading my base image so much simpler compared to rebuilding all the other images! I read a bunch of docs/articles since reading your comment yesterday but couldn't find any mention of this, or better yet an example. Are there some docs I missed? (I didn't look into the spec.)