presentation-nix-flakes/prezentace.md

marp	class	paginate	footer
true	invert	true	Albert Vala, Filip Kohout, Nix flakes & Nix command

Nix flakes & Nix command

---

Nix Command

• Nove nix cli
• Flake support

---

Porovnani

nix-shell -p cowsay #Stare
nix shell nixpkgs#cowsay #Nove
nix run nixpkgs#cowsay #Nove

---

Commandy

Command	Na
flake new	Vytvoreni flaky z template
develop	Build environment shell
shell	temp shell s nejakym programem
config check	Check configu na potencialni chyby
run	Spusti output z flaky

---

Flakes

• Proc?

• Lockfiles.

• Flake inputs

• Na co?

• Cokoliv.

---

Jak pouzit flakes na system configuraci?

• Flake je jen cast zbytek je v normalnich nix filech
• Zbytek konfigurace bere inputy z flaky.
• Neprijdeme o nic jen mame lock file a moznost flake jako inputu

---

Flake example

{
  description = "NixOS configuration";
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    home-manager.url = "github:nix-community/home-manager";
    home-manager.inputs.nixpkgs.follows = "nixpkgs";
    zen-browser.url = "github:0xc000022070/zen-browser-flake";
  };
  outputs = inputs @ {
    nixpkgs,
    home-manager,
    zen-browser,
    ...
  }: {
    nixosConfigurations = {
      laptop = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          ./laptop/configuration.nix
          home-manager.nixosModules.home-manager
          {
            home-manager.useGlobalPkgs = false;
            home-manager.useUserPackages = true;
            home-manager.extraSpecialArgs = {inherit zen-browser;};
            home-manager.users.albert = import ./modules/home.nix;
          }
        ];
      };
    };
  };
}

---

{
  zen-browser,
  config,
  pkgs,
  ...
}: {
  home.username = "nixFreak";
  home.homeDirectory = "/home/nixFreak";
  home.stateVersion = "24.05";
  home.packages = with pkgs;
    [
      cowsay
    ]
    ++ [
      zen-browser.packages."${system}".default
    ];
  programs.home-manager.enable = true;
}

---

Inputs

• nix flake metadata --json | jq - zobrazí vstupy
• lock aktuální verze
• nix flake update - aktualizace všech vstupů
• nix flake update [home-manager] - aktualizace jednoho vstupu
• nix flake show - zobrazí flake strukturu

inputs = {
    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
    nixpkgs-stable.url = "github:nixos/nixpkgs/nixos-24.11";
    nixpkgs-current = "github:nixos/nixpkgs?ref=3058cf84bce1aba7b1820cb24319a171572217ba-dirty";
}

---

Nixos-rebuild

• Je to jen bash script

nixos-rebuild --flake
nh os switch

nix build /etc/nixos#nixosConfigurations.nixos.config.system.build.toplevel \
&& ./result/bin/switch-to-configuration switch

---

Nix writers

• Jednoduchý způsob přidávání skriptů v různých programovacích jazycích do systému ve flake konfiguraci
• Rozdíl oproti klasickému pkgs.writeShellScriptBin
• nixpkgs - pro všechny možnosti konfigurace skriptů
• https://nixos.wiki/wiki/Nix-writers - osekaná wiki

---

pkgs.writers.writeBash "hello-world-bash" {} 
''
echo "Hello world!"
''

pkgs.writers.writePython3 "hello-world-python" {} 
''
print("Hello world!")
''

pkgs.writers.writeRust "hello-world-rust" {} 
''
fn main() {
    println!("Hello world!")
}
''

---

pkgs.writers.writePython3 "hello-world-python" 
{
    libraries = [ pkgs.python3Packages.requests ];

    makeWrapperArgs = [
        "--prefix", "PATH", ":", "${pkgs.sl}/bin",
    ];
} 

''
print("Hello world!")
''