[cbrewster]

While you can copy files from different stages, I wouldn't consider this to be the same thing as composing two base images together. Like the example in the post, you can't take the Rust and NodeJS images and tell Docker to magically merge them. You can copy binaries & libraries from one to the other but that seems extremely tedious and error prone.

Whereas Nix makes it rather trivial to compose together the packages you need (eg Rust, NodeJS) in your environment.