nixfiles/profiles/usb-automount.nix

{pkgs, ...}: let
  usb_data = import ../data/usb_data.nix {};
  enc_usb_mount = pkgs.writeShellScriptBin "enc_usb_mount" ''
    set -x
    ${enc_usb_unmount}/bin/enc_usb_unmount
    cat /secrets/usb_encryption_passphrase | cryptsetup luksOpen ${usb_data.encrypted_path} ${usb_data.mapper_name}_afterboot -
    mount ${usb_data.mapper_path}_afterboot -o rw ${usb_data.mountpoint}
  '';
  enc_usb_unmount = pkgs.writeShellScriptBin "enc_usb_unmount" ''
    set -x
    umount -flR ${usb_data.mountpoint} || true
    cryptsetup close ${usb_data.mapper_name}_afterboot || true
  '';
in {
  environment.systemPackages = [enc_usb_mount enc_usb_unmount];

  systemd.tmpfiles.rules = ["d ${usb_data.mountpoint} - chaos root"];

  systemd.services.enc-usb-mount = {
    path = [pkgs.util-linux pkgs.cryptsetup];
    wantedBy = ["multi-user.target"];
    script = ''
      ${enc_usb_mount}/bin/enc_usb_mount
    '';
  };

  systemd.services.enc-usb-unmount = {
    path = [pkgs.util-linux pkgs.cryptsetup];
    script = ''
      ${enc_usb_unmount}/bin/enc_usb_unmount
    '';
  };

  services.udev.extraRules = ''
    ACTION=="add", ENV{PARTNAME}=="${usb_data.encrypted_partlabel}", ENV{SYSTEMD_WANTS}="enc-usb-mount.service", ENV{UDISKS_PRESENTATION_HIDE}="1"
    ACTION=="remove", ENV{PARTNAME}=="${usb_data.encrypted_partlabel}", ENV{SYSTEMD_WANTS}="enc-usb-unmount.service"
  '';
}