system:
{ pkgs, lib, config, ... }:
let
  systemConfig = { pkgs, ... }: {
    # passwordless ssh server
    services.openssh = {
      enable = true;
      permitRootLogin = "yes";
      extraConfig = "PermitEmptyPasswords yes";
    };

    users = {
      mutableUsers = false;
      # build user
      extraUsers."build" = {
        isNormalUser = true;
        uid = 1000;
        extraGroups = [ "wheel" ];
        password = "";
      };
      users.root.password = "";
    };

    security.sudo.wheelNeedsPassword = false;
    nix.trustedUsers = [ "root" "build" ];
    documentation.nixos.enable = false;

    # builds.sr.ht-image-specific network settings
    networking = {
      hostName = "build";
      dhcpcd.enable = false;
      defaultGateway.address = "10.0.2.2";
      usePredictableInterfaceNames = false; # so that we just get eth0 and not some weird id
      interfaces."eth0".ipv4.addresses = [{
        address = "10.0.2.15";
        prefixLength = 25;
      }];
      enableIPv6 = false;
      nameservers = [
        # OpenNIC anycast
        "185.121.177.177"
        "169.239.202.202"
        # Google as a fallback :(
        "8.8.8.8"
      ];
      firewall.allowedTCPPorts = [ 22 ]; # allow ssh
    };

    environment.systemPackages = [
      pkgs.gitMinimal
      #pkgs.mercurial
      pkgs.curl
      pkgs.gnupg
    ];
  };
  qemuConfig = { pkgs, ... }: {
    imports = [ systemConfig ];
    fileSystems."/".device = "/dev/disk/by-label/nixos";
    boot.initrd.availableKernelModules = [
      "ahci"
      "ehci_pci"
      "sd_mod"
      "usb_storage"
      "usbhid"
      "virtio_balloon"
      "virtio_blk"
      "virtio_pci"
      "virtio_ring"
      "xhci_pci"
    ];
    boot.loader = {
      grub = {
        version = 2;
        device = "/dev/vda";
      };
      timeout = 0;
    };
  };
  config = (import (pkgs.path + "/nixos/lib/eval-config.nix") {
    inherit pkgs system; modules = [ qemuConfig ];
  }).config;
in
import (pkgs.path + "/nixos/lib/make-disk-image.nix") {
  inherit pkgs lib config;
  diskSize = 16000;
  format = "qcow2-compressed";
  contents = [
    { source = pkgs.writeText "gitconfig" ''
        [user]
          name = builds.sr.ht
          email = build@sr.ht
      '';
      target = "/home/build/.gitconfig";
      user = "build";
      group = "users";
      mode = "644";
    }
  ];
}