NixOS

I have been eyeing operating systems with functional package managers for a while now, aka, NixOS or Guix. Reproducible builds, declarative and rollback-able system configuration, system consistency, all sound pretty cool. I have been using NixOS for about a month now.

Installation

I went with their minimal installation ISO. The installation was pretty smooth from start to end, no hitches there. The entire manual is available offline, and is accessible during the installation. Very handy.

Setup

The entire system is configured via /etc/nixos/configuration.nix. Wifi, libinput gestures, audio, locale settings, there are options for literally everything. You can declaratively write down the packages you want installed too. With fresh installs of most distros, I usually fumble with getting things like screen backlight and media keys to work. If I do manage to fix it, I can’t carry it forward to future installations trivially. Getting all my hardware to work on NixOS is as easy as:

{
    server.xserver.libinput.enable = true;  # touchpad
    programs.light.enable = true;           # backlight
    hardware.pulseaudio.enable = true;      # audio
    networking.wireless.enable = true;      # wifi
}

Developing with Nix

Nix makes it easy to enter environments that aren’t affected by your system configuration using nix-shell.

Builds may be generated by specifying a default.nix file, and running nix-build. Conventional package managers require you to specify a dependency list, but there is no guarantee that this list is complete. The package will build on your machine even if you forget a dependency. However, with Nix, packages are installed to /nix/store, and not global paths such as /usr/bin/..., if your project builds, it means you have included every last one.

Issues on most my projects have been “unable to build because libxcb is missing”, or “this version of openssl is too old”. Tools like cargo and pip are poor package managers. While they can guarantee that Rust or Python dependencies are met, they make assumptions about the target system.

For example, this website is now built using Nix, anyone using Nix may simply, clone the repository and run ./generate.sh, and it would just work, while keeping your global namespace clean™:

#! /usr/bin/env nix-shell
#! nix-shell -i bash -p eva pandoc esh

# some bash magic ;)

Dependencies are included with the -p flag, the shell script is executed with an interpreter, specified with the -i flag.

Impressions

NixOS is by no means, simple. As a newcomer, using Nix was not easy, heck, I had to learn a purely functional, lazy language to just build programs. There is a lot to be desired on the tooling front as well. A well fleshed out LSP plugin would be nice (rnix-lsp looks promising).

Being able to rollback changes at a system level is cool. Package broke something? Just nixos-rebuild switch --rollback! Deleted nix by mistake? Find the binary in /nix/store and rollback! You aren’t punished for not thinking twice.

I don’t see myself switching to anything else in the near future, NixOS does a lot of things right. If I ever need to reinstall NixOS, I can generate an image of my current system.