udev

configuration.nix

{ pkgs, config, lib, ... }:
let
  extusbup = pkgs.writeScriptBin "extusb.up" ''
    #!${pkgs.stdenv.shell}
    #cryptsetup luksOpen /dev/extusb1 vmware
    cat /root/keyfile | cryptsetup -v --key-file=- luksOpen /dev/sdc1 vmware
    vgscan
    vgchange -ay vgvmware
    mount /dev/vgvmware/vmware /home/test/Desktop/Virtual
  '';
  extusbdown = pkgs.writeScriptBin "extusb.down" ''
    #!${pkgs.stdenv.shell}
    umount /home/test/Desktop/Virtual
    vgchange -an vgvmware
    cryptsetup luksClose vmware
  '';
in
{
.
.
.
    udev.extraRules = ''
      # External USB hard drive
      ACTION=="add", SUBSYSTEM=="block", ATTRS{model}=="2115            ", NAME="extusb", RUN+="${extusbup}/bin/extusb.up"
      ACTION=="remove", SUBSYSTEM=="block", ATTRS{model}=="2115            ", RUN+="${extusbdown}/bin/extusb.down"
    '';
.
.
.
}

configuration_v2.nix

{
.
.
.
  systemd.services."attach-my-disk" = {
    script = ''
      echo "$(date) attached" >> /tmp/usb.log
    '';
    serviceConfig.Type = "oneshot";
  };
  systemd.services."detach-my-disk" = {
    script = ''
      echo "$(date) detached" >> /tmp/usb.log
    '';
    serviceConfig.Type = "oneshot";
  };
  services.udev.extraRules = ''
    ACTION=="add", ATTRS{vendor}=="0x8086", ENV{SYSTEMD_WANTS}="attach-my-disk.service"
    ACTION=="remove", ATTRS{vendor}=="0x8086", ENV{SYSTEMD_WANTS}="detach-my-disk.service"
  '';
.
.
.
}