NixOS - Reproducible Linux Distribution built around systemd

#nixos

Rok Garbas, @garbas

systemd conf 2016

Nix

"traditional" package managers

Nix

Why Nix

Nix Demo

System management methods

Configuration

Most problems and complexity comes from mutating the state (/usr, /etc, ...)

NixOS

Declarative configuration (1/5)

{
  boot.loader.grub.device = "/dev/sda";
  fileSystem."/".device = "/dev/sda1";

  networking.hostname = "webserver";
  networking.firewall.allowedTCPPorts = [ 80 443 ];

  environment.systemPackages = with pkgs; [ htop vim ];

  services.openssh.enable = true

  services.nginx =
    { enable = true;
      virtualHosts."service.example.com" =
        { forceSSL = true;
          enableACME = true;
          location."/".proxyPass = "....";
        };
    };

  ...
}

Declarative configuration (2/5)

{
  ...

  services.xserver.displayManager.kdm.enable = true;
  services.xserver.desktopManager.kde4.enable = true;
  #services.xserver.desktopManager.kde5.enable = true;

  networking.networkmanager.enable = true

  ...
}

Declarative configuration (3/5)

{
  ...

  systemd.services."hello" = {
    description = "Hello";
    serviceConfig.Type = "oneshot";
    serviceConfig.RemainAfterExit = true;
    wantedBy = [ "multi-user.target" ];
    script = ''
      echo "hello"
    '';
  };

  ...
}

Declarative configuration (4/5)

{
  ...
  # lenovo t410
  boot = {
    kernelParams = [
      # Kernel GPU Savings Options (NOTE i915 chipset only)
      "drm.debug=0" "drm.vblankoffdelay=1" "i915.semaphores=1" "i915.modeset=1"
      "i915.use_mmio_flip=1" "i915.powersave=1" "i915.enable_ips=1"
      "i915.disable_power_well=1" "i915.enable_hangcheck=1"
      "i915.enable_cmd_parser=1" "i915.fastboot=0" "i915.enable_ppgtt=1"
      "i915.reset=0" "i915.lvds_use_ssc=0" "i915.enable_psr=0" "vblank_mode=0"
      "i915.i915_enable_rc6=1"
    ];
    blacklistedKernelModules = [
      # Kernel GPU Savings Options (NOTE i915 chipset only)
      "sierra_net" "cdc_mbim" "cdc_ncm" "btusb"
    ];
  };

  hardware.cpu.intel.updateMicrocode = true;

  ...
}

https://github.com/NixOS/nixos-hardware

Declarative configuration (5/5)

{
  ...

  containers.database =
    { config =
      { config, pkgs, ... }:
      { services.postgresql.enable = true;
        services.postgresql.package = pkgs.postgresql92;
      };
  };

  ...
}

Why NixOS?

NixOS demo

NixOS Community

Caveats of Nix/NixOS

Thank you

Questions?