Can't use derivation from inputs in Nix flake

[DCsunset]

Hi, I’m new to Nix Flakes and want to import a package in my NixOS config. In order to do so, I created a Nix flake for my package shown below:

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs { inherit system; };
      in {
        packages = rec {
          mypkg = pkgs.stdenv.mkDerivation { ... };
          default = mypkg;
        };
      });
}

When I tried to import the derivation in my NixOS configuration, I tried:

{
  inputs = {
    mypkg.url = "path:/path/to/mypkg";
  };

  outputs = { nixpkgs, ... }@inputs: {
    nixosConfigurations = {
      legion = nixpkgs.lib.nixosSystem rec {
        system = "x86_64-linux";
        # pass mypkgs to modules
        specialArgs = {
          mypkgs = {
            mypkg = inputs.mypkg.packages.default.${system};
          };
        };
        modules = [
          ./configuration.nix
        ];
      };
    };
  };
}

But I encountered the error error: attribute 'packages' missing at the mypkg line, and I’m confused how to import it correctly. I searched a lot but still didn’t find any solution. I would appreciate it if anyone could help fix this issue.

Thanks

[voydus]

I think it should be inputs.mypkg.packages.${system}.default (system first) but that wouldn’t explain your error.

I like to open up nix repl, load the flake with :lf . (other flake urls work, but usually I’m j the directory) and then work through tab completion, starting with inputs.mypkg.

The less-interactive way would be to flake show path:/path/to/mypkg

Hope that helps somewhat, I’m on my phone so the commands might be a little off

[DCsunset]

Yes I tried inputs.mypkg.packages.${system}.default but the result is the same. The result of nix flake show is shown below:

path:....
└───packages
    ├───aarch64-darwin
    │   ├───default omitted (use '--all-systems' to show)
    │   └───mypkg omitted (use '--all-systems' to show)
    ├───aarch64-linux
    │   ├───default omitted (use '--all-systems' to show)
    │   └───mypkg omitted (use '--all-systems' to show)
    ├───x86_64-darwin
    │   ├───default omitted (use '--all-systems' to show)
    │   └───mypkg omitted (use '--all-systems' to show)
    └───x86_64-linux
        ├───default: package 'mypkg'
        └───mypkg: package 'mypkg'

It looks good to me though. BTW, I’m using nixos-rebuild switch to deploy my configuration, not sure if that’s relevant to this error.

[NobbZ]

@DCsunset

        specialArgs = {
          mypkgs = {
            mypkg = inputs.mypkg.packages.default.${system};
          };
        };

Here you are adding an argument to your modules, named mypkgs, which otself will be a set with a single child mypkg, which points to an inexisting attrinbute in your flake.

How and where are you actually using this additional argument in your modules?

[DCsunset]

Actually I’m trying to import an emacs package. So I used the package within the home-manager config, which is imported as the same level as configuration.nix:

{ pkgs, mypkgs, ... }:
{
  home-manager.users."${user}" = { lib, ... }: {
    programs.emacs = {
      enable = true;
      package = pkgs.emacs29;
      # emacs packages
      extraPackages = epkgs: [
        mypkgs.mypkg
      ];
    };
  };
}

And the error does point to the line where I access the packages attribute:

error: attribute 'packages' missing

at /nix/store/akf3s0jinsnggpk0z4zm9qpgf8d7d2bb-source/flake.nix:21:23:
       20|           mypkgs = {
       21|             mypkg = inputs.mypkg.packages.default.${system};

So I think it shouldn’t be caused by how I use the pkg right?

[NobbZ]

@DCsunset

21| mypkg = inputs.mypkg.packages.default.${system};

In that case it should be inputs.mypkg.packages.${system}.default.

If that doesn’t fix it, please show the full error, or even better the flakes repositories.

[DCsunset]

The full error is shown below:

building the system configuration...
error:
       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:780:24:

          779|     let f = attrPath:
          780|       zipAttrsWith (n: values:
             |                        ^
          781|         let here = attrPath ++ [n]; in

       … while calling 'g'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:599:19:

          598|           g =
          599|             name: value:
             |                   ^
          600|             if isAttrs value && cond value

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:602:20:

          601|               then recurse (path ++ [name]) value
          602|               else f (path ++ [name]) value;
             |                    ^
          603|         in mapAttrs g;

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:242:72:

          241|           # For definitions that have an associated option
          242|           declaredConfig = mapAttrsRecursiveCond (v: ! isOption v) (_: v: v.value) options;
             |                                                                        ^
          243|

       … while evaluating the option `system.build.toplevel':

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:783:28:

          782|         # Process mkMerge and mkIf properties.
          783|         defs' = concatMap (m:
             |                            ^
          784|           map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))

       … while evaluating definitions from `/nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/nixos/modules/system/activation/top-level.nix':

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:784:137:

          783|         defs' = concatMap (m:
          784|           map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))
             |                                                                                                                                         ^
          785|         ) defs;

       … while calling 'dischargeProperties'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:855:25:

          854|   */
          855|   dischargeProperties = def:
             |                         ^
          856|     if def._type or "" == "merge" then

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/nixos/modules/system/activation/top-level.nix:101:12:

          100|   # Replace runtime dependencies
          101|   system = foldr ({ oldDependency, newDependency }: drv:
             |            ^
          102|       pkgs.replaceDependency { inherit oldDependency newDependency drv; }

       … while calling 'foldr'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/lists.nix:53:20:

           52|   */
           53|   foldr = op: nul: list:
             |                    ^
           54|     let

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/lists.nix:60:8:

           59|         else op (elemAt list n) (fold' (n + 1));
           60|     in fold' 0;
             |        ^
           61|

       … while calling 'fold''

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/lists.nix:56:15:

           55|       len = length list;
           56|       fold' = n:
             |               ^
           57|         if n == len

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/nixos/modules/system/activation/top-level.nix:98:10:

           97|     then throw "\nFailed assertions:\n${concatStringsSep "\n" (map (x: "- ${x}") failedAssertions)}"
           98|     else showWarnings config.warnings baseSystem;
             |          ^
           99|

       … while calling 'showWarnings'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/trivial.nix:414:28:

          413|
          414|   showWarnings = warnings: res: lib.foldr (w: x: warn w x) res warnings;
             |                            ^
          415|

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/trivial.nix:414:33:

          413|
          414|   showWarnings = warnings: res: lib.foldr (w: x: warn w x) res warnings;
             |                                 ^
          415|

       … while calling 'foldr'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/lists.nix:53:20:

           52|   */
           53|   foldr = op: nul: list:
             |                    ^
           54|     let

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/lists.nix:60:8:

           59|         else op (elemAt list n) (fold' (n + 1));
           60|     in fold' 0;
             |        ^
           61|

       … while calling 'fold''

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/lists.nix:56:15:

           55|       len = length list;
           56|       fold' = n:
             |               ^
           57|         if n == len

       … while calling 'g'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:599:19:

          598|           g =
          599|             name: value:
             |                   ^
          600|             if isAttrs value && cond value

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:602:20:

          601|               then recurse (path ++ [name]) value
          602|               else f (path ++ [name]) value;
             |                    ^
          603|         in mapAttrs g;

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:242:72:

          241|           # For definitions that have an associated option
          242|           declaredConfig = mapAttrsRecursiveCond (v: ! isOption v) (_: v: v.value) options;
             |                                                                        ^
          243|

       … while evaluating the option `warnings':

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:783:28:

          782|         # Process mkMerge and mkIf properties.
          783|         defs' = concatMap (m:
             |                            ^
          784|           map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))

       … while evaluating definitions from `/nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/nixos/modules/system/boot/systemd.nix':

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:784:137:

          783|         defs' = concatMap (m:
          784|           map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))
             |                                                                                                                                         ^
          785|         ) defs;

       … while calling 'dischargeProperties'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:855:25:

          854|   */
          855|   dischargeProperties = def:
             |                         ^
          856|     if def._type or "" == "merge" then

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:543:10:

          542|     attrs:
          543|     map (name: f name attrs.${name}) (attrNames attrs);
             |          ^
          544|

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:543:16:

          542|     attrs:
          543|     map (name: f name attrs.${name}) (attrNames attrs);
             |                ^
          544|

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/nixos/modules/system/boot/systemd.nix:422:16:

          421|       mapAttrsToList
          422|         (name: service:
             |                ^
          423|           let

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/nixos/modules/system/boot/systemd.nix:429:16:

          428|             concatLists [
          429|               (optional (type == "oneshot" && (restart == "always" || restart == "on-success"))
             |                ^
          430|                 "Service '${name}.service' with 'Type=oneshot' cannot have 'Restart=always' or 'Restart=on-success'"

       … while calling 'optional'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/lists.nix:285:20:

          284|   */
          285|   optional = cond: elem: if cond then [elem] else [];
             |                    ^
          286|

       … while calling 'g'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:599:19:

          598|           g =
          599|             name: value:
             |                   ^
          600|             if isAttrs value && cond value

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:602:20:

          601|               then recurse (path ++ [name]) value
          602|               else f (path ++ [name]) value;
             |                    ^
          603|         in mapAttrs g;

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:242:72:

          241|           # For definitions that have an associated option
          242|           declaredConfig = mapAttrsRecursiveCond (v: ! isOption v) (_: v: v.value) options;
             |                                                                        ^
          243|

       … while evaluating the option `systemd.services.home-manager-user.serviceConfig':

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:805:59:

          804|       if isDefined then
          805|         if all (def: type.check def.value) defsFinal then type.merge loc defsFinal
             |                                                           ^
          806|         else let allInvalid = filter (def: ! type.check def.value) defsFinal;

       … while calling 'merge'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/types.nix:538:20:

          537|       check = isAttrs;
          538|       merge = loc: defs:
             |                    ^
          539|         mapAttrs (n: v: v.value) (filterAttrs (n: v: v ? value) (zipAttrsWith (name: defs:

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/types.nix:539:35:

          538|       merge = loc: defs:
          539|         mapAttrs (n: v: v.value) (filterAttrs (n: v: v ? value) (zipAttrsWith (name: defs:
             |                                   ^
          540|             (mergeDefinitions (loc ++ [name]) elemType defs).optionalValue

       … while calling 'filterAttrs'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:309:5:

          308|     # The attribute set to filter
          309|     set:
             |     ^
          310|     listToAttrs (concatMap (name: let v = set.${name}; in if pred name v then [(nameValuePair name v)] else []) (attrNames set));

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:310:29:

          309|     set:
          310|     listToAttrs (concatMap (name: let v = set.${name}; in if pred name v then [(nameValuePair name v)] else []) (attrNames set));
             |                             ^
          311|

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:310:62:

          309|     set:
          310|     listToAttrs (concatMap (name: let v = set.${name}; in if pred name v then [(nameValuePair name v)] else []) (attrNames set));
             |                                                              ^
          311|

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/types.nix:539:51:

          538|       merge = loc: defs:
          539|         mapAttrs (n: v: v.value) (filterAttrs (n: v: v ? value) (zipAttrsWith (name: defs:
             |                                                   ^
          540|             (mergeDefinitions (loc ++ [name]) elemType defs).optionalValue

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/types.nix:539:86:

          538|       merge = loc: defs:
          539|         mapAttrs (n: v: v.value) (filterAttrs (n: v: v ? value) (zipAttrsWith (name: defs:
             |                                                                                      ^
          540|             (mergeDefinitions (loc ++ [name]) elemType defs).optionalValue

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:783:28:

          782|         # Process mkMerge and mkIf properties.
          783|         defs' = concatMap (m:
             |                            ^
          784|           map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))

       … while evaluating definitions from `/nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/flake.nix':

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:784:137:

          783|         defs' = concatMap (m:
          784|           map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))
             |                                                                                                                                         ^
          785|         ) defs;

       … while calling 'dischargeProperties'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:855:25:

          854|   */
          855|   dischargeProperties = def:
             |                         ^
          856|     if def._type or "" == "merge" then

       … while evaluating derivation 'home-manager-generation'
         whose name attribute is located at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/stdenv/generic/make-derivation.nix:300:7

       … while evaluating attribute 'buildCommand' of derivation 'home-manager-generation'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/build-support/trivial-builders/default.nix:87:14:

           86|       enableParallelBuilding = true;
           87|       inherit buildCommand name;
             |              ^
           88|       passAsFile = [ "buildCommand" ]

       … while evaluating derivation 'activation-script'
         whose name attribute is located at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/stdenv/generic/make-derivation.nix:300:7

       … while evaluating attribute 'text' of derivation 'activation-script'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/build-support/trivial-builders/default.nix:146:16:

          145|     runCommand name
          146|       { inherit text executable checkPhase allowSubstitutes preferLocalBuild;
             |                ^
          147|         passAsFile = [ "text" ];

       … while calling 'mkCmd'

         at /nix/store/4kkvfkkhr53w8l4kc82j1pml32j3kjrk-source/modules/home-environment.nix:666:17:

          665|       let
          666|         mkCmd = res: ''
             |                 ^
          667|             _iNote "Activating %s" "${res.name}"

       … while calling 'g'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:599:19:

          598|           g =
          599|             name: value:
             |                   ^
          600|             if isAttrs value && cond value

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/attrsets.nix:602:20:

          601|               then recurse (path ++ [name]) value
          602|               else f (path ++ [name]) value;
             |                    ^
          603|         in mapAttrs g;

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:242:72:

          241|           # For definitions that have an associated option
          242|           declaredConfig = mapAttrsRecursiveCond (v: ! isOption v) (_: v: v.value) options;
             |                                                                        ^
          243|

       … while evaluating the option `home-manager.users.user.home.activation.installPackages.data':

       … while calling anonymous lambda

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:783:28:

          782|         # Process mkMerge and mkIf properties.
          783|         defs' = concatMap (m:
             |                            ^
          784|           map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))

       … while evaluating definitions from `/nix/store/4kkvfkkhr53w8l4kc82j1pml32j3kjrk-source/modules/home-environment.nix':

       … from call site

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:784:137:

          783|         defs' = concatMap (m:
          784|           map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))
             |                                                                                                                                         ^
          785|         ) defs;

       … while calling 'dischargeProperties'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/lib/modules.nix:855:25:

          854|   */
          855|   dischargeProperties = def:
             |                         ^
          856|     if def._type or "" == "merge" then

       … while evaluating derivation 'home-manager-path'
         whose name attribute is located at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/stdenv/generic/make-derivation.nix:300:7

       … while evaluating attribute 'passAsFile' of derivation 'home-manager-path'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/build-support/trivial-builders/default.nix:88:7:

           87|       inherit buildCommand name;
           88|       passAsFile = [ "buildCommand" ]
             |       ^
           89|         ++ (derivationArgs.passAsFile or []);

       … while evaluating derivation 'emacs-with-packages-29.0.92'
         whose name attribute is located at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/stdenv/generic/make-derivation.nix:300:7

       … while evaluating attribute 'deps' of derivation 'emacs-with-packages-29.0.92'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/build-support/emacs/wrapper.nix:60:5:

           59|     # one path to the load lists
           60|     deps = runCommand "emacs-packages-deps"
             |     ^
           61|       ({

       … while evaluating derivation 'emacs-packages-deps'
         whose name attribute is located at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/stdenv/generic/make-derivation.nix:300:7

       … while evaluating attribute 'explicitRequires' of derivation 'emacs-packages-deps'

         at /nix/store/4qn2xsmahx2qsafqz1snl6r1k5bwna44-source/pkgs/build-support/emacs/wrapper.nix:62:16:

           61|       ({
           62|         inherit explicitRequires lndir emacs;
             |                ^
           63|         nativeBuildInputs = lib.optional withNativeCompilation gcc;

       error: attribute 'packages' missing

       at /nix/store/mlmykpfjlpj00ryry21n9pjin32wcx4j-source/flake.nix:21:23:

           20|           mypkgs = {
           21|             mypkg = inputs.mypkg.packages.${system}.default;
             |                    ^
           22|           };

The repositories are too large to post here. However, when I tried minimizing my config it does work well surprisingly. The error message is too confusing for me to find where the actual error is.

[DCsunset]

I finally fixed this error by deleting the flake.lock. It seems that with flake.lock, even if I updated my package, it won’t use those changes. That’s also why I can’t reproduce the error when I tried minimizing my config.

Thank you all who helped me with this issue!