Allow overriding configuration from outside #14

aleksi · 2025-10-03T16:38:25Z

aleksi commented

2025-10-03 16:38:25 +00:00

Use case: downstream users may want to override the GNU mirror URL,
as the main ftp.gnu.org repository has caused slow downloads. Now it is possible to
perform e.g.

((import ./default.nix).extend {
  modules = [{ config.aux.mirrors.gnu = "https://www.nic.funet.fi/pub/gnu/ftp.gnu.org/pub/gnu/"; }];
}).config.exports.resolved.packages

Use case: downstream users may want to override the GNU mirror URL, as the main ftp.gnu.org repository has caused slow downloads. Now it is possible to perform e.g. ```nix ((import ./default.nix).extend { modules = [{ config.aux.mirrors.gnu = "https://www.nic.funet.fi/pub/gnu/ftp.gnu.org/pub/gnu/"; }]; }).config.exports.resolved.packages ```

aleksi added 1 commit 2025-10-03 16:38:25 +00:00

Allow overriding configuration from outside e2be002d7c

Use case: downstream users may want to override the GNU mirror URL,
as the main FTP has caused slow downloads. Now it is possible to
perform e.g.

  (import ./default.nix) {
   config.aux.mirrors.gnu = "https://www.nic.funet.fi/pub/gnu/ftp.gnu.org/pub/gnu/";
  }

aleksi changed title from ~~Allow overriding configuration from outside~~ to WIP: Allow overriding configuration from outside

2025-10-03 17:15:15 +00:00

aleksi force-pushed receive-config from e2be002d7c to c728bc74f0

2025-10-03 18:18:12 +00:00

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aleksi force-pushed receive-config from c728bc74f0 to 8cdaee81c8

2025-10-03 18:20:27 +00:00

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aleksi changed title from ~~WIP: Allow overriding configuration from outside~~ to Allow overriding configuration from outside

2025-10-03 18:20:42 +00:00

aleksi commented

2025-10-03 18:24:05 +00:00

Incorporates #13. Otherwise builtins.mapAttrs in src/exports/default.nix will cause eager evaluation of packages (including fetching) with the default mirror regardless

Incorporates #13. Otherwise `builtins.mapAttrs` in `src/exports/default.nix` will cause eager evaluation of packages (including fetching) with the default mirror regardless

austreelis commented

2025-10-03 19:28:00 +00:00

I think it would be best to just include your commit and avoid mixing PRs. We'll just have to wait until #13 for mirror overrides to work properly, making foundation extensible still has value in tiself in my opinion.

I cherry-picked it locally and it looks good to me, so I'd approve id if it was just your changes :)

I think it would be best to just include your commit and avoid mixing PRs. We'll just have to wait until #13 for mirror overrides to work properly, making foundation extensible still has value in tiself in my opinion. I cherry-picked it locally and it looks good to me, so I'd approve id if it was just your changes :)

aleksi force-pushed receive-config from 8cdaee81c8 to 24507466fe

2025-10-03 19:29:46 +00:00

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aleksi commented

2025-10-03 19:30:54 +00:00

Yes, that's a good idea. I've rebased the branch

srxl commented

2025-10-03 23:57:01 +00:00

I wonder if it's worth wrapping the extend function we expose to call extend and then return the resolved package set, so that consumers using extend don't need to access config.export.resolved.packages on the result. It seems like that's the only thing we export publicly here, so I don't see too much reason not to.

I wonder if it's worth wrapping the extend function we expose to call extend and then return the resolved package set, so that consumers using extend don't need to access `config.export.resolved.packages` on the result. It seems like that's the only thing we export publicly here, so I don't see too much reason not to.

aleksi force-pushed receive-config from 24507466fe to 25d6d22fe2

2025-10-04 05:55:54 +00:00

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aleksi commented

2025-10-04 05:57:40 +00:00

That seems better indeed. This new revision accesses the export automatically.

srxl approved these changes 2025-10-04 07:32:08 +00:00

srxl left a comment

Nice, looks good to me!

austreelis requested changes 2025-10-04 09:53:57 +00:00

Dismissed

default.nix Outdated

					
				@ -13,2 +13,4 @@

				in

				result.config.exports.resolved.packages

				// {

				  extend = overrides: (result.extend overrides).config.exports.resolved.packages;

austreelis commented

2025-10-04 09:53:44 +00:00

Because extend now returns the resolved packages, the extended foundation loses its extend attribute. I think this should be

{
  system ? builtins.currentSystem,
}:
let
  pins = import ./npins;
  lib = import pins.lib;

  modules = import ./src;

  result = lib.modules.run {
    modules = (builtins.attrValues modules) ++ [ { config.aux.system = system; } ];
  };

  export = result:
    result.config.exports.resolved.packages // { extend = extend result; };

  extend = result: overrides: export (result.extend overrides);
in
export result

to allow doing ((import <foundation> {}). extend { /*...*/ }). extend { /*...*/ } as many times as we want. A bit more complex but I didn't see an obviously better way :)

Edit: corrected my suggestion, it was wrong (now it's good :3)

Because `extend` now returns the resolved packages, the extended foundation loses its `extend` attribute. I think this should be ```nix { system ? builtins.currentSystem, }: let pins = import ./npins; lib = import pins.lib; modules = import ./src; result = lib.modules.run { modules = (builtins.attrValues modules) ++ [ { config.aux.system = system; } ]; }; export = result: result.config.exports.resolved.packages // { extend = extend result; }; extend = result: overrides: export (result.extend overrides); in export result ``` to allow doing `((import <foundation> {}). extend { /*...*/ }). extend { /*...*/ }` as many times as we want. A bit more complex but I didn't see an obviously better way :) Edit: corrected my suggestion, it was wrong (now it's good :3)

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