You might be interested in this: https://github.com/uber/makisu

I've not used it but it's on my list to try out, the explicit caching I think ties in with what you're after:

* Requires no elevated privileges or containerd/Docker daemon, making the build process portable.

* Uses a distributed layer cache to improve performance across a build cluster.

* Provides control over generated layers with a new optional keyword #!COMMIT, reducing the number of layers in images.

* Is Docker compatible. Note, the Dockerfile parser in Makisu is opinionated in some scenarios. More details can be found here.

I can't edit any more, but I'd really be interested in people's experiences with it.

Nowadays docker server, when run with the experimental flag, allows you to build images with the `--squash` option, so your whole image will contain a single layer.

Alternatively you can use buildah [1] to build your images via a script, but you'll lose the cache docker puts in place.

[1] https://buildah.io/

Why do you want to avoid multiple layers. Performance?

Build performance, image size and deployment speed mostly.

Each layer is a write only operation. So if you `RUN some_build.sh` and then `RUN rm junk`, you basically do nothing to reduce the final image size. So you see a lot of like `RUN some_build.sh && rm -rf junk`. There's some overhead with each layer as well.

Size of the resulting container is my understanding.