nixos/factorio: disable builting mods introduced with Factorio Space Age

[no-mood]

Nixpkgs version

• Unstable (25.05)

Describe the bug

The Factorio module currently installs built-in mods (like Space Age) even when they are not explicitly specified. This results in players being unable to join servers if they do not own these mods, which is not the intended behavior.

I am creating this issue to make life easier for those who encounter this problem.
There is already a potential fix in progress (#388285), but I am opening this issue regardless to document the problem and track its resolution.

Let me know if more information or testing is needed.

Steps to reproduce

1. Set up a Factorio server using the NixOS module without specifying any mods:

{
  services.factorio = {
    enable = true;
    openFirewall = true;
  };
}

2. Start the server
3. Try to join the server from a client without built-in mods like Space Age.

Expected behaviour

The server should not automatically include built-in mods that are not explicitly listed in the configuration. Clients without these mods should be able to connect without issues.

Screenshots

No response

Relevant log output

Additional context

No response

System metadata

 - system: `"x86_64-linux"`
 - host os: `Linux 6.13.7, NixOS, 25.05 (Warbler), 25.05.20250319.a84ebe2`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.24.12`
 - nixpkgs: `/nix/store/1728d3jg85mkz2w2cvk6vi74i30fn6x7-source`

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• I assert that this is not a duplicate of an existing issue.
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[hustlerone]

This might just be a config issue.

Try adding this to factorio.json:

    "mods": 
    [
      
      {
        "name": "base",
        "enabled": true
      },
      
      {
        "name": "elevated-rails",
        "enabled": false
      },
      
      {
        "name": "quality",
        "enabled": false
      },
      
      {
        "name": "space-age",
        "enabled": false
      }
    ]

[no-mood]

This might just be a config issue.

Try adding this to factorio.json:

    "mods": 
    [
      
      {
        "name": "base",
        "enabled": true
      },
      
      {
        "name": "elevated-rails",
        "enabled": false
      },
      
      {
        "name": "quality",
        "enabled": false
      },
      
      {
        "name": "space-age",
        "enabled": false
      }
    ]

You mean mod-list.json? Or this in the nix config?

[hustlerone]

This might just be a config issue.
Try adding this to factorio.json:

    "mods": 
    [
      
      {
        "name": "base",
        "enabled": true
      },
      
      {
        "name": "elevated-rails",
        "enabled": false
      },
      
      {
        "name": "quality",
        "enabled": false
      },
      
      {
        "name": "space-age",
        "enabled": false
      }
    ]

You mean mod-list.json? Or this in the nix config?

Yes, in the config. Specifically in extraSettingsFile (less nix-y), or an equivalent in Nix syntax in the extraSettings attrset. The DLC are technically mods but built-in.

If you're actually using mods it might make sense to use the extraSettings attrset since it'll all get merged cleanly.

Here's the options for factorio the service: https://search.nixos.org/options?channel=unstable&show=services.factorio.extraSettings&from=0&size=50&sort=relevance&type=packages&query=factorio

[no-mood]

I'm not sure why it works now (having upgraded to the latest experimental version) with this fix. Here's how I got it to work::

{
  pkgs,
  config,
  lib,
  ...
}:
let
  placeholder = config.sops.placeholder;
  mod-list-json = pkgs.writeText "mod-list.json" (
    builtins.toJSON {
      mods = [
        {
          name = "base";
          enabled = true;
        }
        {
          name = "elevated-rails";
          enabled = false;
        }
        {
          name = "quality";
          enabled = false;
        }
        {
          name = "space-age";
          enabled = false;
        }
      ];
    }
  );
in
{

  services.factorio = {
    enable = true;
    openFirewall = true;
    package = pkgs.factorio-headless-experimental;
  };
  # Service tends to fail when system is booting up, this gives it time to try again once network is online
  systemd.services.factorio.serviceConfig.RestartSec = 10;
  systemd.services.factorio.postStart = ''
    cat ${mod-list-json} > /var/lib/${config.services.factorio.stateDirName}/mods/mod-list.json
  '';
}

I've tried this before without success. Feedback welcome :)

[hustlerone]

look at the working dir's config file

[JustAlternate]

This is still a problem

Would it be possible to create something like this ?:

service.factorio.mod-list = ''
      mods = [
        {
          name = "base";
          enabled = true;
        }
        {
          name = "elevated-rails";
          enabled = false;
        }
        {
          name = "quality";
          enabled = false;
        }
        {
          name = "space-age";
          enabled = false;
        }
      ];
''

[hustlerone]

try setting the package to factorio instead of factorio space age