108 lines
2.9 KiB
Nix
108 lines
2.9 KiB
Nix
/*
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Manages the things that are needed for a traditional nix-channel based
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configuration to work.
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See also
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- ./nix.nix
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- ./nix-flakes.nix
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*/
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{ config, lib, ... }:
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let
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inherit (lib)
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mkDefault
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mkIf
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mkOption
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stringAfter
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types
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;
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cfg = config.nix;
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in
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{
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options = {
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nix = {
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channel = {
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enable = mkOption {
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description = lib.mdDoc ''
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Whether the `nix-channel` command and state files are made available on the machine.
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The following files are initialized when enabled:
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- `/nix/var/nix/profiles/per-user/root/channels`
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- `/root/.nix-channels`
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- `$HOME/.nix-defexpr/channels` (on login)
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Disabling this option will not remove the state files from the system.
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'';
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type = types.bool;
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default = true;
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};
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};
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nixPath = mkOption {
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type = types.listOf types.str;
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default =
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if cfg.channel.enable
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then [
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"nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
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"nixos-config=/etc/nixos/configuration.nix"
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"/nix/var/nix/profiles/per-user/root/channels"
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]
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else [ ];
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defaultText = ''
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if nix.channel.enable
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then [
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"nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
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"nixos-config=/etc/nixos/configuration.nix"
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"/nix/var/nix/profiles/per-user/root/channels"
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]
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else [];
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'';
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description = lib.mdDoc ''
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The default Nix expression search path, used by the Nix
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evaluator to look up paths enclosed in angle brackets
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(e.g. `<nixpkgs>`).
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'';
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};
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};
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system = {
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defaultChannel = mkOption {
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internal = true;
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type = types.str;
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default = "https://nixos.org/channels/nixos-unstable";
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description = lib.mdDoc "Default NixOS channel to which the root user is subscribed.";
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};
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};
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};
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config = mkIf cfg.enable {
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environment.extraInit =
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mkIf cfg.channel.enable ''
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if [ -e "$HOME/.nix-defexpr/channels" ]; then
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export NIX_PATH="$HOME/.nix-defexpr/channels''${NIX_PATH:+:$NIX_PATH}"
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fi
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'';
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environment.extraSetup = mkIf (!cfg.channel.enable) ''
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rm --force $out/bin/nix-channel
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'';
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# NIX_PATH has a non-empty default according to Nix docs, so we don't unset
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# it when empty.
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environment.sessionVariables = {
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NIX_PATH = cfg.nixPath;
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};
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nix.settings.nix-path = mkIf (! cfg.channel.enable) (mkDefault "");
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system.activationScripts.nix-channel = mkIf cfg.channel.enable
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(stringAfter [ "etc" "users" ] ''
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# Subscribe the root user to the NixOS channel by default.
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if [ ! -e "/root/.nix-channels" ]; then
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echo "${config.system.defaultChannel} nixos" > "/root/.nix-channels"
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fi
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'');
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};
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}
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