So Nix is ultimately a tool for making and sharing reproducible package builds. It has a binary cache, but it's not necessary. Like Ports, packages get built by default.
Docker, on the other hand, is a distribution and execution mechanism. It provides an abstract way to move around a fully assembled, ready-to-go service or application running in isolation.
It's entirely reasonable to use both. You can use Nix to build and manage docker images and make extremely minimalist docker images. You can use Nix knowing that the entire process is perfectly reproducible, and the Docker containerization is only a final integration step.
With this, you sorta get the best of both worlds. You get a reproducible build (and if done right, also a reproducible dev environment via nix-shell) and with Docker you get the ability to build and run a prepped copy with a well-defined interface.
Docker really doesn't provide a way to reproduce a built image from scratch. You sort of have to trust and build on existing images, and most folks making bulk images appeal to external tooling outside docker files to do this.
So Nix is ultimately a tool for making and sharing reproducible package builds. It has a binary cache, but it's not necessary. Like Ports, packages get built by default.
Docker, on the other hand, is a distribution and execution mechanism. It provides an abstract way to move around a fully assembled, ready-to-go service or application running in isolation.
It's entirely reasonable to use both. You can use Nix to build and manage docker images and make extremely minimalist docker images. You can use Nix knowing that the entire process is perfectly reproducible, and the Docker containerization is only a final integration step.
With this, you sorta get the best of both worlds. You get a reproducible build (and if done right, also a reproducible dev environment via nix-shell) and with Docker you get the ability to build and run a prepped copy with a well-defined interface.
Docker really doesn't provide a way to reproduce a built image from scratch. You sort of have to trust and build on existing images, and most folks making bulk images appeal to external tooling outside docker files to do this.