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

• Nové nix cli
• Flake support

---

Porovnani

nix-shell -p cowsay #Old
nix shell nixpkgs#cowsay #New
nix run nixpkgs#cowsay #New

---

Commandy

Command	Na
flake new	Vytvoření flaky z template
develop	Build environment shell
shell	temp shell s nějakým programem
config check	Check configu na potenciální chyby
run	Spustí output z flaky

---

Flakes

• Proč?

• Lockfiles.

• Flake inputs

• Na co?

• Cokoliv.

---

Nix command + flakes

• temp shell

nix shell nixpkgs#alejandra
nix shell github:kamadorueda/alejandra

• Show output attr

nix flake show github:kamadorueda/alejandra

---

Jak použít flakes na systémovou configuraci?

• Flakes používáme jen na management input a output atributů
• Zbytek konfigurace používá inputy definované ve flake.nix

---

{
  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

inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/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

---

Remote building

• nixos-rebuild --target-host nixFreak@192.168.8.32 switch --flake .#default

• --use-remote-sudo

• --build-host - konfigurace tady

• --target-host - konfigurace tam

---

Virtual machine

nix run github:nix-community/nixos-generators -- -c ./flake.nix --flake '#default' -f vm --disk-size 20480

---

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!")
''