What if you could reinstall
your laptop in 30 minutes?

Šta ako bi mogao reinstalirati
laptop za 30 minuta?

NixOS — how I use itNixOS — kako ga ja koristim
Stefan Matić

Before we startPrije nego počnemo

• I'm bad at development and design.Loš sam u developmentu i dizajnu.
• This entire presentation is vibe coded.Cijela ova prezentacija je vibe codeana.

Built with Claude Code.Napravljeno uz Claude Code.

Setting up a new machine, usuallyKako obično izgleda postavljanje novog računara

• Install the OSInstaliraš OS
• Install your apps, one by oneInstaliraš aplikacije, jednu po jednu
• Copy your dotfiles, if you kept themKopiraš dotfileove, ako si ih sačuvao
• Fix the things you forgotPopraviš ono što si zaboravio
• Two weeks later: still finding things you forgotDvije sedmice kasnije: još uvijek otkrivaš šta si zaboravio

Nothing keeps a record of what you did to the system.Nigdje ne ostaje zapisano šta si uradio sa sistemom.

Nix ≠ NixOS

You can use Nix without NixOS. Most of this talk is about NixOS.Nix možeš koristiti i bez NixOS-a. Ovo predavanje je uglavnom o NixOS-u.

What NixOS does differentlyŠta NixOS radi drugačije

$ sudo apt install docker.io
$ sudo systemctl enable --now docker
$ sudo usermod -aG docker me

virtualisation.docker.enable = true;
users.users.me.extraGroups = [ "docker" ];

My desktop, from the actual fileMoj desktop, iz pravog fajla

# hosts/zvijer/configuration.nix (excerpt)
imports = [
  ./hardware-configuration.nix
  ../_common/client.nix
  ../../system/security/yubikey.nix
];

boot.loader.grub = {
  enable = true;
  efiSupport = true;
  configurationLimit = 20;
  theme = pkgs.sleek-grub-theme.override { withStyle = "dark"; };
};

services.nordvpn.enable = true;

hardware.openrazer = {
  enable = true;
  users = [ userSettings.username ];
};

The full file is about 400 lines. sudo nixos-rebuild switch makes the system match it.Cijeli fajl ima oko 400 linija. sudo nixos-rebuild switch uskladi sistem s njim.

My GPU history, straight from git logMoja GPU historija, direktno iz git log-a

Each swap is a commit: drivers, Wayland variables, Ollama ROCm → CUDA. The last one was 3 files, about 40 lines.Svaka zamjena je jedan commit: drajveri, Wayland varijable, Ollama ROCm → CUDA. Zadnja je bila 3 fajla, oko 40 linija.

Every rebuild is also a generation. If one doesn't work, boot the previous one from GRUB, or:Svaki rebuild je i nova generacija. Ako nešto ne radi, butaš prethodnu iz GRUB-a, ili:

$ sudo nixos-rebuild switch --rollback

Flakes: "experimental", used by everyoneFlakeovi: „eksperimentalni", a svi ih koriste

nix.settings.experimental-features =
  [ "nix-command" "flakes" ];

# flake.nix (simplified)
{
  inputs = {
    nixpkgs.url =
      "github:nixos/nixpkgs?ref=nixos-unstable";
    home-manager.url =
      "github:nix-community/home-manager";
    nix-darwin.url =
      "github:nix-darwin/nix-darwin/master";
  };

  outputs = { nixpkgs, ... }: {
    nixosConfigurations.ZVIJER =
      nixpkgs.lib.nixosSystem {
        modules = [
          ./hosts/zvijer/configuration.nix
        ];
      };
  };
}

One repo, every machineJedan repo, sve mašine

gitlab.com/stefan-matic/nixos-config

nix-darwin

$ darwin-rebuild switch --flake .#macbook

# hosts/macbook + hosts/_common/darwin.nix (excerpt)
security.pam.services.sudo_local.touchIdAuth = true;

homebrew = {
  enable = true;
  casks = [
    "ghostty"
    "raycast"
    "slack"
    "keepassxc"
  ];
};

home-manager.users.${userSettings.username} = {
  imports = [ ../../home/darwin.nix ];
};

Shared config, in layersZajednički config, u slojevima

Change a shared file → every machine that imports it gets the change on its next rebuild.Promijeniš zajednički fajl → svaka mašina koja ga importuje dobije promjenu na sljedećem rebuildu.

Setting up a machine with NixOSPostavljanje mašine s NixOS-om

1. Install NixOS from USB. The installer generates hardware-configuration.nix.Instaliraš NixOS s USB-a. Instaler generiše hardware-configuration.nix.
2. Clone the repo and copy that file into hosts/<machine>/.Kloniraš repo i kopiraš taj fajl u hosts/<mašina>/.
3. Rebuild:Rebuild:

$ git clone https://gitlab.com/stefan-matic/nixos-config ~/.dotfiles
$ sudo nixos-rebuild switch --flake ~/.dotfiles#starlabs

nixos-infect

# fresh Contabo Ubuntu 24.04 VPS, root, SSH keynovi Contabo Ubuntu 24.04 VPS, root, SSH ključ

# Contabo names it vmi123456.contaboserver.net;Contabo ga nazove vmi123456.contaboserver.net;
# NixOS doesn't accept dots in the hostnameNixOS ne prihvata tačke u hostnameu
$ hostname myserver

$ curl https://raw.githubusercontent.com/elitak/\
    nixos-infect/master/nixos-infect \
    | NIX_CHANNEL=nixos-25.11 bash -x

# …a few minutes and a reboot later…par minuta i jedan reboot kasnije
$ ssh root@myserver
[root@myserver:~]# nixos-version
25.11 …

What else I use every dayŠta još koristim svaki dan

• Config in git. git log shows when and why something changed.Config u gitu. git log pokaže kad je i zašto nešto promijenjeno.
• Rollback. Every rebuild is a generation; the previous ones stay in the boot menu.Rollback. Svaki rebuild je generacija; prethodne ostaju u boot meniju.
• Try without installing. nix shell nixpkgs#htop — gone when the shell closes.Probaj bez instaliranja. nix shell nixpkgs#htop — nestane kad zatvoriš shell.
• Pinned versions. flake.lock pins every input. All machines get the same versions until I run nix flake update.Zaključane verzije. flake.lock zaključa svaki input. Sve mašine imaju iste verzije dok ne pokrenem nix flake update.
• Lots of packages. nixpkgs has 100,000+ of them.Puno paketa. nixpkgs ih ima preko 100.000.

Each project directory gets its own toolsSvaki folder projekta ima svoje alate

One approach for every language, instead of nvm, pyenv, rbenv, tfenv, sdkman…Jedan pristup za sve jezike, umjesto nvm, pyenv, rbenv, tfenv, sdkman…

$ cd ~/Workspace/project-a
$ devbox init
$ devbox add terraform@1.5.7 nodejs@20 awscli2
$ devbox generate direnv && direnv allow

$ terraform version        # Terraform v1.5.7
$ cd ../project-b
$ terraform version        # Terraform v1.4.0
$ cd ~ && terraform version
zsh: command not found: terraform

The Nix languageNix jezik

# hosts/zvijer/configuration.nix (top)
{ config, pkgs, lib, inputs, ... }:

let
  env = import ./env.nix { inherit pkgs; };
  inherit (env) systemSettings userSettings;
in
{
  home-manager.users.${userSettings.username} = {
    imports = [ ../../home/stefanmatic.nix ];
  };
}

[ pkgs.callPackage ./foo { } ]

[ (pkgs.callPackage ./foo { }) ]

Error messagesPoruke o greškama

{ config, lib, ... }: {
  options.services.myapp.enable =
    lib.mkEnableOption "myapp";
  imports = lib.optional
    config.services.myapp.enable ./extra.nix;
}

error:
  … while evaluating the attribute
    'config.services.myapp.enable'
    at /nix/store/r5l6…-source/lib/modules.nix:404:9
  … while calling the 'seq' builtin
    at /nix/store/r5l6…-source/lib/modules.nix:404:18
  … while evaluating the module argument
    `config' in ":anon-1":
  … if you get an infinite recursion here, you
    probably reference `config` in `imports`.

  (stack trace truncated; use '--show-trace')

  error: infinite recursion encountered

Happiness over timeSreća kroz vrijeme

The learning curveKrivulja učenja

Who it's forZa koga je

It's not a fix for everything. A lot of things don't work out of the box — they take tweaking and trial and error.Nije rješenje za sve. Dosta stvari ne radi odmah — treba ih podešavati i isprobavati.

How to startKako početi

• Install just the Nix package manager on your current distro or Mac — no reinstallInstalirajte samo Nix package manager na trenutni distro ili Mac — bez reinstalacije
• Or run NixOS in a VM firstIli prvo pokrenite NixOS u VM-u
• Start with one configuration.nix; add flakes and Home Manager laterPočnite s jednim configuration.nix; flakeove i Home Manager dodajte kasnije

Questions?Pitanja?

If you didn't like this talk:Ako vam se predavanje nije svidjelo:

$ sudo nixos-rebuild switch --rollback