proper hack, works without disko too

{
  config,
  pkgs,
  lib,
  ...
}:

let
  installBootLoader =
    (import (pkgs.path + "/nixos/modules/system/boot/loader/generic-extlinux-compatible") {
      inherit config lib pkgs;
    }).config.content.system.build.installBootLoader;

  populateFirmware =
    (import (pkgs.path + "/nixos/modules/installer/sd-card/sd-image-aarch64.nix") {
      inherit config lib pkgs;
    }).sdImage.populateFirmwareCommands;

  installCmd = pkgs.writeShellScript "populate-boot.sh" ''
    set -e && export PATH=${pkgs.coreutils}/bin:$PATH
    ${installBootLoader} "$@"

    ln -s "/boot" "$NIX_BUILD_TOP/firmware" 
    cd "$NIX_BUILD_TOP" && ${populateFirmware} 
    echo "include usercfg.txt" >> /boot/config.txt
  '';
in
{
  system.build.installBootLoader = lib.mkForce installCmd;
}

Possibly a general flake question: what is the syntax for applying a flake from a non-github repo and using a specific branch?

So far I'm trying:

nix run --extra-experimental-features 'nix-command flakes' 'github:nix-community/disko/latest#disko-install' -- --write-efi-boot-entries --flake 'https://codeberg.org/higara/legacy-nix-configuration.git?ref=add-klaes#klaes' --disk nvme0 /dev/nvme0n1

And getting:

error: Failed to open archive (Unrecognizde archive format)
.disko-install-wrapped: line 234: artifacts[1]: unbound variable

Possibly a general flake question: what is the syntax for applying a flake from a non-github repo and using a specific branch?

So far I'm trying:

nix run --extra-experimental-features 'nix-command flakes' \
    'github:nix-community/disko/latest#disko-install' -- \
    --write-efi-boot-entries \
    --flake 'https://codeberg.org/higara/legacy-nix-configuration.git?ref=add-klaes#klaes' \
    --disk nvme0 /dev/nvme0n1

And getting:

error: Failed to open archive (Unrecognizde archive format)
.disko-install-wrapped: line 234: artifacts[1]: unbound variable

proper hack, works without disko too

{
  config,
  pkgs,
  lib,
  ...
}:

let
  installBootLoader =
    (import (pkgs.path + "/nixos/modules/system/boot/loader/generic-extlinux-compatible") {
      inherit config lib pkgs;
    }).config.content.system.build.installBootLoader;

  populateFirmware =
    (import (pkgs.path + "/nixos/modules/installer/sd-card/sd-image-aarch64.nix") {
      inherit config lib pkgs;
    }).sdImage.populateFirmwareCommands;

  installCommand = pkgs.writeShellScript "populate-boot.sh" ''
    set -e && export PATH=${pkgs.coreutils}/bin:$PATH
    ${builtins.replaceStrings [ "firmware/" ] [ "boot/" ] populateFirmware}
    echo "include usercfg.txt" >> boot/config.txt
    ${installBootLoader} "$@"
  '';
in
{
  system.build.installBootLoader = lib.mkForce installCommand;
}

How do you guys handle diffrent /dev/* paths,

i use nixos anywhere to add nodes to my cluster but some nodes will have /dev/nvme0n1 as root and some /dev/sda1 and so on

Is there way to automatically select which ever is avaialable ?