Sorry, mini-bump:

I'm trying to use the disko-install command to create a custom bootable USB that has an entire NixOS system (including persistent storage and access to git and neovim, plus a few other goodies).

After running sudo nix run 'github:nix-community/disko/latest#disko-install' -- --flake .#image --disk os /dev/sdc, things seem to get built/copied etc., but it finally halts with this error:

efiSysMountPoint = '/boot' is not a mounted partition. Is the path configured correctly?
Traceback (most recent call last):
  File "/nix/store/diy6lcklb9r4k18l6plg6yj9chn3pg19-systemd-boot/bin/systemd-boot", line 431, in <module>
    main()
  File "/nix/store/diy6lcklb9r4k18l6plg6yj9chn3pg19-systemd-boot/bin/systemd-boot", line 411, in main
    run([CHECK_MOUNTPOINTS])
  File "/nix/store/diy6lcklb9r4k18l6plg6yj9chn3pg19-systemd-boot/bin/systemd-boot", line 58, in run
    return subprocess.run(cmd, check=True, text=True, stdout=stdout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/c9m6yd8fg1flz2j5r4bif1ib5j20a0cy-python3-3.12.8/lib/python3.12/subprocess.py", line 571, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['/nix/store/686vaqa40l0vxcp1ll54cbvlrmn9kn55-check-mountpoints']' returned non-zero exit status 1.
Failed to install bootloader
disko-install failed
rmdir: failed to remove '/mnt/disko-install-root': Directory not empty

My disko (and NixOS configuration) is pretty simple and the problem occurs even with a minimal configuration:

{
  disko.devices = {
    nodev."/" = {
      fsType = "tmpfs";
      mountOptions = [
        "size=2G"
        "defaults"
        "mode=755"
      ];
    };
    nodev."/home/raj" = {
      fsType = "tmpfs";
      mountOptions = [
        "size=2G"
        "defaults"
        "mode=777"
      ];
    };
    disk = {
      os = {
        imageName = "nixos-usb-stick";
        imageSize = "60G";
        type = "disk";
        content = {
          type = "gpt";
          partitions = {
            ESP = {
              type = "EF00";
              priority = 0;
              end = "1G";
              content = {
                type = "filesystem";
                format = "vfat";
                mountpoint = "/boot";
                mountOptions = ["defaults" "umask=0077"];
              };
            };
            root = {
              priority = 1;
              end = "-0";
              content = {
                type = "luks";
                name = "root";
                initrdUnlock = true;
                extraFormatArgs = ["--pbkdf argon2id"];
                content = {
                  type = "btrfs";
                  extraArgs = ["-f"];
                  subvolumes = {
                    "/nix" = {
                      mountpoint = "/nix";
                      mountOptions = ["compress=zstd" "noatime"];
                    };
                    "/persist" = {
                      mountpoint = "/persist";
                      mountOptions = ["compress=zstd" "noatime"];
                    };
                    "/data" = {
                      mountpoint = "/data";
                      mountOptions = ["compress=zstd" "noatime"];
                    };
                  };
                };
              };
            };
          };
        };
      };
    };
  };
}

Is there anything obvious I'm missing?

Thank you for answering. Guess I am not messing with that then, more complex than I thought it would be.
Btw, just watched your talk on YouTube (NixCon2023)

• How is the state for checking for partition alignment automatically? For example does it warn me when partition is not aligned?
• I heard it is possible to use YubiKey with luks2 in disko, is there any documentation example for that?

Also, I have:

nixosConfigurations = {
      book-of-the-azure-sky = lib.nixosSystem {
        system = "x86_64-linux";
        specialArgs.inputs = inputs;
        modules = [
          disko.nixosModules.disko
          <...disko-config.nix here...>
        ];

and disko-config.nix:

{
  device ? throw "Set this to your disk device, e.g. /dev/sda",
  ...
}: {
  disko.devices = {
    disk.main = {
      inherit device;
      type = "disk";
<...>

How to use disko-config.nix in modules and set the device in disko-config.nix to /dev/sdb?