{ config, lib, pkgs, ... }: with lib; let cfg = config.nix.gc; in { ###### interface options = { nix.gc = { automatic = mkOption { default = false; type = types.bool; description = "Automatically run the garbage collector at a specific time."; }; dates = mkOption { default = "03:15"; type = types.str; description = '' Specification (in the format described by systemd.time 5) of the time at which the garbage collector will run. ''; }; options = mkOption { default = ""; example = "--max-freed $((64 * 1024**3))"; type = types.str; description = '' Options given to nix-collect-garbage when the garbage collector is run automatically. ''; }; }; }; ###### implementation config = { systemd.services.nix-gc = { description = "Nix Garbage Collector"; script = "exec ${config.nix.package}/bin/nix-store --gc ${cfg.options}"; startAt = optionalString cfg.automatic cfg.dates; }; }; }