52 lines
1.3 KiB
Nix
52 lines
1.3 KiB
Nix
{ config, pkgs, ... }:
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with pkgs.lib;
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let
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failed = map (x: x.message) (filter (x: !x.assertion) config.assertions);
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showWarnings = res: fold (w: x: builtins.trace "[1;31mwarning: ${w}[0m" x) res config.warnings;
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in
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{
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options = {
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assertions = mkOption {
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internal = true;
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default = [];
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example = [ { assertion = false; message = "you can't enable this for that reason"; } ];
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merge = pkgs.lib.mergeListOption;
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description = ''
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This option allows modules to express conditions that must
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hold for the evaluation of the system configuration to
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succeed, along with associated error messages for the user.
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'';
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};
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warnings = mkOption {
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internal = true;
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default = [];
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type = types.listOf types.string;
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example = [ "The `foo' service is deprecated and will go away soon!" ];
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description = ''
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This option allows modules to show warnings to users during
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the evaluation of the system configuration.
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'';
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};
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};
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config = {
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# This option is evaluated always. Thus the assertions are checked
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# as well. Hacky!
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environment.systemPackages = showWarnings (
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if [] == failed then []
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else throw "\nFailed assertions:\n${concatStringsSep "\n" (map (x: "- ${x}") failed)}");
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};
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}
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