BuildKit
Concurrent, cache-efficient, and Dockerfile-agnostic builder toolkit
...But before that, we needed to make sure that we have capabilities to continue adding such features in the future and a solid foundation to extend on. Quite soon it was clear that we would need to redefine most of the fundamentals about how we even define a build operation and needed a clean break from the current codebase. A proposal was written, and development started in the open under the new repository.