BuildKit
Concurrent, cache-efficient, and Dockerfile-agnostic builder toolkit
... in April and had proposals and user requests for many similar additions. 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.