unnix

Reproducible Nix environments without installing Nix

Usage

[!Warning] Unnix is alpha software. I recommend against running it on long-running production servers in its current state.

nix shell github:figsoda/unnix

cargo install unnix --locked

To use unnix, start by creating unnix.kdl, unnix's manifest file

unnix init -p jq ripgrep

Now you can enter the environment with

unnix env

This will generate unnix.lock.json and put you in a shell with jq and rg. Make sure to commit the lockfile to your VCS to keep your environment reproducible.

How it works

This is a very simplified view of what happens when you run nix develop.

flowchart TB

nix(nix) --> | download | expr --> | evaluate | drv
drv --> | outputs | path --> | query | cache

cache -->| hit | download(download to the Nix store)
cache -->| miss | build(build the derivation)
drv -.- build

cache(
  binary cache
  e.g. cache.nixos.org
)

drv(derivations)

expr(
  Nix expressions
  e.g. Nixpkgs
)

path(store paths)

Downloading and evaluating Nixpkgs can take a long time, especially in ephemeral environments like CI pipelines. Unnix avoids that by removing derivations from the picture altogether, and getting the store paths directly from services like Hydra or Devbox.

flowchart TB
unnix --> | lockfile absent or outdated | update --> | Hydra / Devbox | paths
unnix --> | up-to-date lockfile | paths
paths --> | query | cache

cache --> | hit | download(download to the unnix store)
cache --> | miss | miss

cache(
  binary cache
  e.g. cache.nixos.org
)

miss(
  fail
)

paths(store paths)

unnix(unnix)

update(update lockfile)

Platform support

Limitations

• No setup hooks

  Unnix does not have access to stdenv, and therefore cannot run the setup hooks or any user-specified shellHooks. Instead, it tries its best to emulate the behavior of setup hooks like pkg-config, so that dependencies can be picked up without executing any hooks.

• No evaluation

  Unnix does not evaluate Nix expressions. You cannot use .override or .overrideAttrs on packages, and are limited to the attributes the resolver exposes, e.g. Hydra jobs.

• No builds

  Unnix cannot build anything, and strictly relies on binary caches. This means no unfree packages if you are using the default set of caches.

Related projects

• nix-bundle

• runix

Documentation

See docs/README.md

Changelog

See CHANGELOG.md