#+PROPERTY: header-args :mkdirp yes

* Systems

I have opted to use NixOS for my systems moving forward. You can read a bit more
about this move [[https://blog.gabrielsimmer.com/posts/from-guix-to-nixos][here]]. I haven't dabbled with custom configuration too much so
this is pretty close to the default configuration.

** London

   London is my primary desktop.

#+begin_src nix :tangle nix/configuration.nix
{ config, pkgs, ... }:

{
  imports =
    [
      ./hardware-configuration.nix
    ];

  nixpkgs.config.allowUnfree = true;

  boot.kernelPackages = pkgs.linuxPackages_latest;

  # Use the systemd-boot EFI boot loader.
  boot.loader.systemd-boot.enable = true;
  boot.loader.efi.canTouchEfiVariables = true;

  networking.hostName = "london";

  # i18n stuff.
  time.timeZone = "Europe/London";
  i18n.defaultLocale = "en_US.UTF-8";
  console = {
    font = "Lat2-Terminus16";
    keyMap = "us";
  };

  # Networking stuff.
  networking.useDHCP = false;
  networking.interfaces.enp4s0.useDHCP = true;
  services.tailscale.enable = true;

  # Enable the X11 windowing system.
  services.xserver.enable = true;
  services.xserver.videoDrivers = [ "nvidia" ];

  hardware.opengl = {
    enable = true;
    extraPackages = with pkgs; [
      vaapiIntel
      vaapiVdpau
      libvdpau-va-gl
    ];
    setLdLibraryPath = true;
    driSupport32Bit = true;
  };
  # Required for Proton games to function.
  programs.steam.enable = true;

  # Enable the GNOME Desktop Environment.
  services.xserver.displayManager.gdm.enable = true;
  services.xserver.desktopManager.gnome.enable = true;

  # Configure keymap in X11
  services.xserver.layout = "us";

  # Disabled and replaced with Pipewire.
  hardware.pulseaudio.enable = false;
  security.rtkit.enable = true;
  services.pipewire = {
    enable = true;
    alsa.enable = true;
    alsa.support32Bit = true;
    pulse.enable = true;
    jack.enable = true;
  };

  programs.zsh.enable = true;
  users.users.gsimmer = {
    isNormalUser = true;
    shell = pkgs.zsh;
    extraGroups = [ "wheel" "networkmanager" ];
  };

  environment.systemPackages = with pkgs; [
    vim
    wget
    firefox
    emacs
    curl
    podman
    tailscale
  ];
  services.flatpak.enable = true;
  xdg.portal.enable = true;
  programs.mtr.enable = true;
  programs.gnupg.agent = {
    enable = true;
    enableSSHSupport = true;
  };

  networking.firewall.enable = false;

  boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
  
  # This value determines the NixOS release from which the default
  # settings for stateful data, like file locations and database versions
  # on your system were taken. It‘s perfectly fine and recommended to leave
  # this value at the release version of the first install of this system.
  # Before changing this value read the documentation for this option
  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
  system.stateVersion = "21.05"; # Did you read the comment?

}
#+end_src

My goal here is to leverage the hardware configuration generated by
the NixOS to seperate out the specific-to-my-current-hardware configuration.

#+begin_src nix :tangle nix/hardware-configuration.nix
{ config, lib, pkgs, modulesPath, ... }:

{
  imports =
    [ (modulesPath + "/installer/scan/not-detected.nix")
    ];

  boot.initrd.availableKernelModules = [ "nvme" "xhci_pci" "ahci" "usbhid" "usb_storage" "sd_mod" ];
  boot.initrd.kernelModules = [ ];
  boot.kernelModules = [ "kvm-amd" ];
  boot.extraModulePackages = [ ];

  services.xserver = {
    libinput = {
      enable = true;
      mouse = { accelProfile = "flat"; };
    };
  };

  fileSystems."/" =
    { device = "/dev/disk/by-uuid/eb8699bd-a9e9-4166-8879-559b244caa20";
      fsType = "ext4";
      options = [ "noatime" "nodiratime" "discard" ];
    };

  fileSystems."/boot" =
    { device = "/dev/disk/by-uuid/D582-4408";
      fsType = "vfat";
      options = [ "noatime" "nodiratime" "discard" ];
    };

  fileSystems."/mnt/wd" =
    { device = "/dev/disk/by-partlabel/WD";
      fsType = "ext4";
      options = [ "noatime" "nodiratime" "discard" ];
    };

  fileSystems."/mnt/fhg" =
    { device = "/dev/disk/by-label/FHG";
      fsType = "ext4";
      options = [ "noatime" "nodiratime" "discard" ];
    };

  swapDevices =
    [ { device = "/dev/disk/by-uuid/8a0c74ad-a88f-4ecd-a6ac-d7985355bce6"; }
    ];

  # high-resolution display
  hardware.video.hidpi.enable = lib.mkDefault true;
}
#+end_src

** Raspberry Pis

   I have two Raspberry Pis - a 3B+ ("watcher"), and a 4 ("panda"). Watcher
   serves as a watchdog for my self hosted services, usually living on Panda.

*** The Installer Image

    Very minimal changes required here, only really need to enabled the SSH daemon
    and add my key so I can push the actual configuration.

    I might investigate bundling the "real" configurations into the live installer
    image, so I have to run fewer commands.

    [[https://nixos.wiki/wiki/NixOS_on_ARM#Getting_the_installer][More info on the NixOS Wiki]]
   
#+begin_src nix :tangle nix/image-configuration.nix
{ ... }: {
  imports = [
    <nixpkgs/nixos/modules/installer/sd-card/sd-image-aarch64.nix>
  ];

  services.sshd.enable = true;
  services.ntp.enable = true;
  
  users.users.gsimmer = {
    isNormalUser = true;
    extraGroups = [ "wheel" ];
    password = "pass"; # This gets changed. Don't get any ideas.
    openssh.authorizedKeys.keys = ["ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAILIztwQxt+jqroFONSgq+xzPMuE2I5Dq/zWPQ8RcTYJr gabriel@gitgalaxy.com"];
  };
}

#+end_src

*** Watcher

   Watcher is my Raspberry Pi 3B+ responsible for monitoring various
   services and devices on my network (and generally the wider web).
   It uses [[https://github.com/gmemstr/platypus][Platypus]] (my custom monitoring platform) for this, along
   with some cron jobs to curl the services themselves.

   Actually declaractive install of Platypus is TODO, once I have the
   next release tagged.
   
#+begin_src nix :tangle nix/watcher-configuration.nix
{ config, pkgs, lib, ... }: {

  boot.loader.grub.enable = false;
  boot.loader.generic-extlinux-compatible.enable = true;
  boot.kernelPackages = pkgs.linuxPackages_latest;

    
  services.sshd.enable = true;
  services.ntp.enable = true;
  
  users.users.gsimmer = {
    isNormalUser = true;
    extraGroups = [ "wheel" ];
    password = "pass"; # This gets changed. Don't get any ideas.
    openssh.authorizedKeys.keys = ["ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAILIztwQxt+jqroFONSgq+xzPMuE2I5Dq/zWPQ8RcTYJr gabriel@gitgalaxy.com"];
  };
  
  environment.systemPackages = [ pkgs.git pkgs.curl ];

  systemd.user.services.ensure-curlscript = {
    script = ''
      # At some point this will pull down a more complete script.
      echo "Done!"
    '';
    wantedBy = [ "multi-user.target" ];
  };

  # Enable cron services
  services.cron = {
    enable = true;
    systemCronJobs = [
      "*/5 * * * *  gsimmer  curl -I -o /dev/null -w \"$(date)|\\%{http_code}\" https://pw.gmem.ca > /home/gsimmer/pw-status"
      "*/5 * * * *  gsimmer  curl -I -o /dev/null -w \"$(date)|\\%{http_code}\" https://hue.gmem.ca > /home/gsimmer/hue-status"
    ];
  };

  fileSystems = {
    "/" = {
      device = "/dev/disk/by-label/NIXOS_SD";
      fsType = "ext4";
    };
  };

  networking.firewall.enable = false;

}
#+end_src

*** Panda

   Panda is a general-purpose Raspberry Pi 4, responsible for hosting
   some network shares and my password manager (using [[https://github.com/dani-garcia/vaultwarden][Vaultwarden]]).

   Largely TODO, this currently runs Raspbian until I'm happy with my
   testbed.

#+begin_src nix :tangle nix/panda-configuration.nix
{ ... }: {
  imports = [
    <nixpkgs/nixos/modules/installer/sd-card/sd-image-aarch64.nix>
  ];
  # put your own configuration here, for example ssh keys:
  users.extraUsers.root.openssh.authorizedKeys.keys = [
     "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAILIztwQxt+jqroFONSgq+xzPMuE2I5Dq/zWPQ8RcTYJr gabriel@gitgalaxy.com"
  ];
}
#+end_src