Disko-install fails without any verbose message

[deep4lpha]

Hi,

I'm struggling to get disko-install to work.

1. I boot a qemu vm with minimal install
2. I remount /nix to have more space mount -o remount,size=10G,noatime /nix/.rw-store
3. I copy over my flake (shown below)
4. I generate hardware-config for my flake with nixos-generate-config --no-filesystems --root /tmp/cfg and copy it to my flake
5. I run sudo nix --extra-experimental-features 'flakes nix-command' run github:nix-community/disko#disko-install -- --flake '.#nix-playground' --disk main /dev/sda --show-trace
6. After download and "these 173 derivations will be built" I get Failed to build NixOS configuration.

When I use sudo nix --extra-experimental-features 'flakes nix-command' run github:nix-community/disko -- --mode disko <path/to/disk-config.nix> and then do the regular flake nixos install all works fine.

Below is my flake.nix (I stripped out anything just to leave basic host config and this below still fails to install):

{
  description = "disko test";

  inputs = {
    # Specify the source of Home Manager and Nixpkgs.
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";

    disko.url = "github:nix-community/disko";
    disko.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs =
    {
      nixpkgs,
      disko,
      ...
    }@inputs:
    let
      system = "x86_64-linux";
      my_overlays = import ./overlays (inputs // { inherit system; });

     pkgs = import nixpkgs {
	inherit system;
     };
      hosts = {
        nix-playground = {
          username = "myuser";
        };
        server = {
          username = "root";
        };
      };

      mkSystem =
        hostName: opts:
        nixpkgs.lib.nixosSystem {
          inherit system;
          modules = [
           #{ nixpkgs.overlays = nix_overlays; }
            ./nixos/${hostName}/disk-config.nix
            disko.nixosModules.disko
            ./nixos/${hostName}/configuration.nix

          ];
        };
    in
    {
      nixosConfigurations = builtins.mapAttrs mkSystem hosts;
    };
}

The nixos/nix-playground/configuration.nix:

{ config, pkgs, ... }:

{
  imports = [
    ./hardware-configuration.nix # generate with nixos-generate-config
  ];

  boot.loader.systemd-boot.enable = true;
  networking.hostName = "nix-playground";
  services.openssh.enable = true;

  environment.systemPackages = with pkgs; [
    zsh
    git
    neovim
  ];
  users.users.myuser = {
    isNormalUser = true;
    extraGroups = [ "wheel" ];
    openssh.authorizedKeys.keys = [
      "key here"
    ];
  };

  system.stateVersion = "25.11";
}

And finally the nixos/nix-playground/disk-config.nix:

{
  disko.devices = {
    disk = {
      main = {
        type = "disk";
        device = "/dev/disk/by-diskseq/1";
        content = {
          type = "gpt";
          partitions = {
            ESP = {
              priority = 1;
              name = "ESP";
              start = "1M";
              end = "128M";
              type = "EF00";
              content = {
                type = "filesystem";
                format = "vfat";
                mountpoint = "/boot";
                mountOptions = [ "umask=0077" ];
              };
            };
            root = {
              size = "100%";
              content = {
                type = "btrfs";
                extraArgs = [ "-f" ]; # Override existing partition
                # Subvolumes must set a mountpoint in order to be mounted,
                # unless their parent is mounted
                subvolumes = {
                  # Subvolume name is different from mountpoint
                  "/rootfs" = {
                    mountpoint = "/";
                  };
                  # Subvolume name is the same as the mountpoint
                  "/home" = {
                    mountOptions = [ "compress=zstd" ];
                    mountpoint = "/home";
                  };
                  # Sub(sub)volume doesn't need a mountpoint as its parent is mounted
                  "/home/myuser" = { };
                  # Parent is not mounted so the mountpoint must be set
                  "/nix" = {
                    mountOptions = [
                      "compress=zstd"
                      "noatime"
                    ];
                    mountpoint = "/nix";
                  };
                };

              };
            };
          };
        };
      };
    };
  };
}

[johanjk]

This sounds a lot like everything is working as intended. Please elaborate on your problem.

Did you read and follow the quickstart?

[deep4lpha]

Thanks, I followed quickstart. The issue is that neither disk partitioning nor installation is carried out - it just stops. When I run the disko --flake .. --mode .. command and then manually do nixos-install it all works fine. Might it be an issue with available disk space? Normally when I run into it on 4gb or less machines I get a verbose error that storage is full.