DIsko failed to install bootloader

[RedJ1ve]

I'm having an issue when trying to use disko-install from nixpkgs. Looked through issues but the only similar issue was with bcachefs and changing --mode didnt fix anything for me.

The installation fails with the following error at the bootloader installation step:

efiSysMountPoint = '/boot' is not a mounted partition. Is the path configured correctly?

Traceback (most recent call last):
  File "/nix/store/fnbphh5spf2a1yydylpx0z4jl04yr6s3-systemd-boot/bin/systemd-boot", line 448, in <module>
    main()
  File "/nix/store/fnbphh5spf2a1yydylpx0z4jl04yr6s3-systemd-boot/bin/systemd-boot", line 428, in main
    run([CHECK_MOUNTPOINTS])
  File "/nix/store/fnbphh5spf2a1yydylpx0z4jl04yr6s3-systemd-boot/bin/systemd-boot", line 57, in run
    return subprocess.run(cmd, check=True, text=True, stdout=stdout)
  File "/nix/store/iyff8129iampdw13nlfqalzhxy8y1hi9-python3-3.13.6/lib/python3.13/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args, output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/nix/store/il12adhgpk1xnqk56jl28f1g1pcjaifp-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

Full log excerpt

Click to expand

umount: /mnt/disko-install-root: not mounted
++ realpath /dev/nvme0n1
+ disk=/dev/nvme0n1
+ lsblk -a -f
...
+ cryptsetup -q luksFormat /dev/disk/by-partlabel/disk-main-luks --key-file /tmp/clevis.key
Failed to open key file.
+ rm -rf /tmp/tmp.PgkzLT1qo1
Copying store paths
Loading nix database
installing the boot loader...
setting up /etc...

Configuration

{ inputs, pkgs, ... }: {
  imports = [ inputs.disko.nixosModules.default ];

  disko.devices = {
    disk.main = {
      type = "disk";
      device = "/dev/sda";
      content = {
        type = "gpt";
        partitions = {
          ESP = {
            size = "500M";
            type = "EF00";
            content = {
              type = "filesystem";
              format = "vfat";
              mountpoint = "/boot";
              mountOptions = [ "umask=0077" ];
            };
          };
          luks = {
            size = "100%";
            content = {
              type = "luks";
              name = "crypted";
              settings = {
                allowDiscards = true;
                keyFile = "/tmp/clevis.key";
              };
              content = {
                type = "lvm_pv";
                vg = "pool";
              };
              preCreateHook = ''
                echo "[*] Generating random keyfile..."
                ${pkgs.coreutils}/bin/dd if=/dev/urandom of=/tmp/keyfile bs=1 count=64
              '';
              postCreateHook = ''
                echo "[*] Binding LUKS volume with Clevis (TPM2 + FIDO2)..."
                ${pkgs.clevis}/bin/clevis-luks-bind -k /tmp/keyfile -d /dev/disk/by-partlabel/luks -s 1 \
                  '{"t":2,"pins":{"tpm2":{"pcr_ids":"0,2,4,7"},"fido2":[{},{}]}}'

                echo "[*] Shredding temporary keyfile..."
                ${pkgs.coreutils}/bin/shred -u /tmp/keyfile
              '';
            };
          };
        };
      };
    };

    lvm_vg.pool = {
      type = "lvm_vg";
      lvs = {
        swap = {
          size = "4G";
          content = {
            type = "swap";
            discardPolicy = "both";
            resumeDevice = true;
          };
        };
        btrfs = {
          size = "100%";
          content = {
            type = "btrfs";
            mountpoint = "/";
            subvolumes = {
              "/root" = { mountpoint = "/"; };
              "/home" = { mountpoint = "/home"; mountOptions = [ "compress=zstd" ]; };
              "/nix" = { mountpoint = "/nix"; mountOptions = [ "compress=zstd" "noatime" ]; };
              "/persist" = { mountpoint = "/persist"; mountOptions = [ "compress=zstd" ]; };
              "/log" = { mountpoint = "/var/log"; mountOptions = [ "compress=zstd" ]; };
            };
            postCreateHook = ''
              echo "[*] Creating root-blank snapshot..."
              MNTPOINT=$(mktemp -d)
              mount /dev/mapper/pool-btrfs "$MNTPOINT"
              trap 'umount "$MNTPOINT"; rm -rf "$MNTPOINT"' EXIT
              btrfs subvolume snapshot -r "$MNTPOINT/root" "$MNTPOINT/root-blank"
              echo "[+] Snapshot created: /root-blank"
            '';
          };
        };
      };
    };
  };
}

Any help would be much appreciated.