nix/nixos/hosts/nixos-vm-02/disks.nix

{
  boot.loader.grub.device = "/dev/sda";
  boot.initrd.luks.devices."sda2".device = "/dev/sda2";

  disko.devices = {
    disk = {
      sda = {
        device = "/dev/sda";
        content = {
          type = "table";
          format = "gpt";
          partitions = [ 
            {
              name = "BOOT";
              start = "0%";
              end = "550MiB";
              bootable = true;
              flags = [ "esp" ];
              fs-type = "fat32";
              content = {
                type = "filesystem";
                format = "vfat";
                mountpoint = "/boot";
              };
            } # partition 1
            { 
              name = "ROOT";
              start = "550MiB";
              end = "100%";
              content = {
                type = "luks";
                name = "LUKS-ROOT";
                extraOpenArgs = [ "--allow-discards" ];
                settings.keyFile = "/tmp/secret.key";
                content = {
                  type = "btrfs";
                  extraArgs = [ "-f" ];
                  subvolumes = {
                    "/root" = {
                      mountpoint = "/";
                      mountOptions = [ "compress=zstd" "noatime" ];
                    }; # root
                    "/home" = {
                      mountpoint = "/home";
                      mountOptions = [ "compress=zstd" "noatime" ];
                    }; # home
                    "/nix" = {
                      mountpoint = "/nix";
                      mountOptions = [ "compress=zstd" "noatime" ];
                    }; # nix
                  }; # subvolumes
                }; # content.content
              }; # content
            } # partition 2
          ]; # partitions
        }; # content
      }; # sda
    }; # disk
  }; # disko.devices
} # root