Comment by juliosueiras

the focus of nix in the build process is the ideal of if you have three build inputs bash 4, gcc 4.8.<patch>, libc <whatever version> , and the source of the package being the same(hash-wise) , the output is very much(for most cases) going to be the same, since nix itself(even on non-nixos) uses very little of the system stuff, it won't be using the system libc, gcc, bash, ncurses, etc, it will use its own that is lock to a version down to the hash, it follow a target(with exact spec) -> output , where as Dockerfile more resemble, of a build that is output first , and not doing build very often, this is why Nix have their own CI/CD system, Hydra to allow ensure daily or even hourly safety of reproducible builds