Can't get nixos-config to work

Help
1

I am new to NixOS, did my first build with this flake

{
 description = "NixOS Config";

 inputs = {
   nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

   home-manager.url = "github:nix-community/home-manager";
   home-manager.inputs.nixpkgs.follows = "nixpkgs";

   hardware.url = "github:nixos/nixos-hardware";
 };

 outputs = { self, nixpkgs, home-manager, ... }@inputs: {

   # build: 'nixos-rebuild --flake .#the-hostname'
   nixosConfigurations = {
     jnix = nixpkgs.lib.nixosSystem {
       system = "x86_64-linux";
       specialArgs = { inherit inputs; };
       modules = [
         ./nixos/configuration.nix
       ];
     };
   };

   # Available through 'home-manager --flake .#janmejay@jnix'
   homeConfigurations = {
     "janmejay@jnix" = home-manager.lib.homeManagerConfiguration {
       system = "x86_64-linux";
       pkgs = nixpkgs.legacyPackages.x86_64-linux; # Home-manager wants 'pkgs'
       extraSpecialArgs = { inherit inputs; };
       modules = [
           ./home-manager/home.nix
       ];
     };
   };
 };
}

Src: GitHub - janmejay/nixos.d: NixOS config

After successful rebuild switch and reboot attempt to run nixos-option fails with

janmejay@jnix:~/nixos.d(master○) » nixos-option
terminate called after throwing an instance of 'nix::ThrownError'
  what():  error:
       … while evaluating the attribute 'options'

         at /nix/store/4cpakzyvfw1rmm9v5i3387x6jd2h1v86-source/nixos/default.nix:15:17:

           14| {
           15|   inherit (eval) pkgs config options;
             |                 ^
           16|

       … while evaluating the attribute 'options'

         at /nix/store/4cpakzyvfw1rmm9v5i3387x6jd2h1v86-source/lib/modules.nix:333:9:

          332|         _type = "configuration";
          333|         options = checked options;
             |         ^
          334|         config = checked (removeAttrs config [ "_module" ]);

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: file 'nixos-config' was not found in the Nix search path (add it using $NIX_PATH or -I)

       at «none»:0: (source not available)
[1]    36703 abort (core dumped)  nixos-option
janmejay@jnix:~/nixos.d(master○) »

I tried manipulating NIX_PATH and now it looks like it doesn’t like my flake definition

janmejay@jnix:~ » echo $NIX_PATH                                                                                                                         134 ↵
nixpkgs=flake:nixpkgs:/nix/var/nix/profiles/per-user/root/channels
janmejay@jnix:~ » export NIX_PATH=$NIX_PATH:nixos-config=/home/janmejay/nixos.d/flake.nix
janmejay@jnix:~ » nixos-option
terminate called after throwing an instance of 'nix::ThrownError'
  what():  error:
       … while evaluating the attribute 'options'

         at /nix/store/4cpakzyvfw1rmm9v5i3387x6jd2h1v86-source/nixos/default.nix:15:17:

           14| {
           15|   inherit (eval) pkgs config options;
             |                 ^
           16|

       … while evaluating the attribute 'options'

         at /nix/store/4cpakzyvfw1rmm9v5i3387x6jd2h1v86-source/lib/modules.nix:333:9:

          332|         _type = "configuration";
          333|         options = checked options;
             |         ^
          334|         config = checked (removeAttrs config [ "_module" ]);

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: The option `description' does not exist. Definition values:
       - In `/home/janmejay/nixos.d/flake.nix': "NixOS Config"
[1]    60432 abort (core dumped)  nixos-option
janmejay@jnix:~ »

But nix flake check seems happy with the way the flake is defined.

janmejay@jnix:~/nixos.d(master○) » nix flake check
janmejay@jnix:~/nixos.d(master○) » echo $?
0
janmejay@jnix:~/nixos.d(master○) »

I temporarily deleted the key anyway

diff --git a/flake.nix b/flake.nix
index 2458d95..5c3fda0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,5 +1,5 @@
 {
- description = "NixOS Config";
+ # description = "NixOS Config";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

but then the error changed to

janmejay@jnix:~/nixos.d(master⚡) » nixos-option
terminate called after throwing an instance of 'nix::ThrownError'
  what():  error:
       … while evaluating the attribute 'options'

         at /nix/store/4cpakzyvfw1rmm9v5i3387x6jd2h1v86-source/nixos/default.nix:15:17:

           14| {
           15|   inherit (eval) pkgs config options;
             |                 ^
           16|

       … while evaluating the attribute 'options'

         at /nix/store/4cpakzyvfw1rmm9v5i3387x6jd2h1v86-source/lib/modules.nix:333:9:

          332|         _type = "configuration";
          333|         options = checked options;
             |         ^
          334|         config = checked (removeAttrs config [ "_module" ]);

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: The option `inputs' does not exist. Definition values:
       - In `/home/janmejay/nixos.d/flake.nix':
           {
             hardware = {
               url = "github:nixos/nixos-hardware";
             };
             home-manager = {
           ...
[1]    71960 abort (core dumped)  nixos-option
janmejay@jnix:~/nixos.d(master⚡) »

Flake check still looks good

janmejay@jnix:~/nixos.d(master⚡) » nix flake check
warning: Git tree '/home/janmejay/nixos.d' is dirty
janmejay@jnix:~/nixos.d(master⚡) » echo $?
0
janmejay@jnix:~/nixos.d(master⚡) »

What am I missing?

2

IINM the nixos-option command doesn’t work with flakes.

3

Thanks @Brisingr05,

Is there an alternative (or hack / workaround)? What is the best way to check what keys / values exist?

I thought this may be the best way to learn about attributes I can set to configure the environment the way I want.

I haven’t tried using nix repl yet (for discovering options, or anything else really), is there a way to get that to work with flakes?

4

You either use nix eval or nix repl. Taking services.openssh.enable for example:

$ nix eval /home/janmejay/nixos.d#nixosConfigurations.jnix.config.services.openssh.enable

or

$ nix repl
nix repl> :lf /home/janmejay/nixos.d
nix repl> nixosConfigurations.jnix.config.services.openssh.enable
5

Great! that does it. Thanks a lot!

1 Like