build.sh

#!/usr/bin/env bash

nix-build '<nixpkgs/nixos>' -A config.system.build.sdImage --option system aarch64-linux -I nixos-config=./default.nix

default.nix

{ pkgs, config, lib, ... }:
  let
    users = import ../common/users.nix { pkgs = pkgs; };
  in
    {
      imports = [
        <nixpkgs/nixos/modules/installer/cd-dvd/sd-image-raspberrypi4.nix>
        ./hardware-configuration.nix
      ];

      sdImage = {
        compressImage = false;
      };

      users.extraUsers = users;

      networking = {
        hostName = "chii";
        domain = "jaen.me";
        dhcpcd.enable = false;
        useDHCP = false;
        wireless.enable = false;
        defaultGateway = "192.168.1.1";
        nameservers = [ "192.168.1.2" "1.1.1.1" "8.8.8.8" "8.8.4.4" ];
        interfaces = {
          eth0 = {
            ipv4 = {
              addresses = [{
                address = "192.168.1.3";
                prefixLength = 24;
            }];
            #  routes = [
            #    { address = "192.168.1.3/24"; prefixLength = 0; via = "192.168.1.1"; }
            #  ];
            };
          };
        };
      };
      
      services.openssh = {
        enable = true;
        permitRootLogin = lib.mkForce "no";
        passwordAuthentication = false;
        listenAddresses = [{ addr = "0.0.0.0"; }];
      };
      
      systemd.services.openssh.wantedBy = lib.mkOverride 10 [ 
        "default.target"
      ];
    }

hardware-configuration.nix

{ config, lib, pkgs, ... }:
  {
    imports = [ 
      <nixpkgs/nixos/modules/installer/scan/not-detected.nix>
    ];

    boot.initrd.availableKernelModules = [ "usbhid" ];
    boot.initrd.kernelModules = [ ];
    boot.initrd.checkJournalingFS = false;
    boot.kernelModules = [ ];
    boot.extraModulePackages = [ ];

    boot.loader.grub.enable = false;
    boot.loader.raspberryPi = {
      enable = true;
      version = 4;
    };

    hardware.enableRedistributableFirmware = true;

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

    swapDevices = [{ 
      device = "/swapfile";
      size = 2048;
    }];

    nix.maxJobs = lib.mkDefault 4;
    powerManagement.cpuFreqGovernor = lib.mkDefault "ondemand";
  }