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nixos/rust-motd: refactor assertion and TOML generation

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* `sort (<)` also works for strings (TIL!), so no need for comparing
  length and whether all keys from `cfg.settings` exist in `cfg.order`
  (slightly less overhead).

* Don't build another piece of JSON (`orderedSections`), simply use
  `cfg.settings`/`cfg.order` with `__structuredAttrs` to ensure a
  properly ordered TOML.

  This also has the upside of not having to do quote hackery.

* Also, a freeform submodule isn't strictly needed because we don't have
  any special options defined, so replacing that with
  `attrsOf format.type`.

Co-authored-by: Silvan Mosberger <github@infinisil.com>
This commit is contained in:
Maximilian Bosch 2023-09-27 12:45:41 +02:00
parent d77b59b41d
commit 57de6a8550
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GPG key ID: 9A6EEA275CA5BE0A
1 changed files with 13 additions and 25 deletions
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38
nixos/modules/programs/rust-motd.nix
View file

@ -6,31 +6,20 @@ let
cfg = config.programs.rust-motd;
format = pkgs.formats.toml { };
orderedSections = listToAttrs
(imap0
(i: attr: nameValuePair "env${toString i}" {
${attr} = cfg.settings.${attr};
})
cfg.order);
# Order the sections in the TOML according to the order of sections
# in `cfg.order`.
# This is done by
# * creating an attribute set with keys `env0`/`env1`/.../`envN`
# where `env0` contains the first section and `envN` the last
# (in the form of `{ sectionName = { /* ... */ }}`)
# * the declarations of `env0` to `envN` in ascending order are
# concatenated with `jq`. Now we have a JSON representation of
# the config in the correct order.
# * this is piped to `json2toml` to get the correct format for rust-motd.
motdConf = pkgs.runCommand "motd.conf"
(orderedSections // {
{
__structuredAttrs = true;
inherit (cfg) order settings;
nativeBuildInputs = [ pkgs.remarshal pkgs.jq ];
})
}
''
cat "$NIX_ATTRS_JSON_FILE" \
| jq '${concatMapStringsSep " + " (key: ''."${key}"'') (attrNames orderedSections)}' \
| jq '.settings as $settings
| .order
| map({ key: ., value: $settings."\(.)" })
| from_entries' -r \
| json2toml /dev/stdin "$out"
'';
in {
@ -60,8 +49,10 @@ in {
default = attrNames cfg.settings;
defaultText = literalExpression "attrNames cfg.settings";
description = mdDoc ''
The order of the sections in [](#opt-programs.rust-motd.settings) implies
the order of sections in the motd. Since attribute sets in Nix are always
The order of the sections in [](#opt-programs.rust-motd.settings).
By default they are ordered alphabetically.
Context: since attribute sets in Nix are always
ordered alphabetically internally this means that
```nix
@ -89,9 +80,7 @@ in {
'';
};
settings = mkOption {
type = types.attrsOf (types.submodule {
freeformType = format.type;
});
type = types.attrsOf format.type;
description = mdDoc ''
Settings on what to generate. Please read the
[upstream documentation](https://github.com/rust-motd/rust-motd/blob/main/README.md#configuration)
@ -106,8 +95,7 @@ in {
`programs.rust-motd` is incompatible with `users.motd`!
'';
}
{ assertion = length cfg.order == length (attrNames cfg.settings)
&& all (section: cfg.settings?${section}) cfg.order;
{ assertion = sort (a: b: a < b) cfg.order == attrNames cfg.settings;
message = ''
Please ensure that every section from `programs.rust-motd.settings` is present in
`programs.rust-motd.order`.