nix-git/modules/nix-gc.nix

{ config, pkgs, ... }:
{
  # Garbage collection: Delete generations older than 5 days and then delete unreachable store objects.

  # https://nixos.wiki/wiki/Storage_optimization#Automation
  # https://nixos.wiki/wiki/Storage_optimization#Removing_old_generations
  nix.gc = {
    automatic = true;
    dates = "weekly";
    options = "--delete-older-than 5d";
  };

  # We need to explicitly run garbage collection for user profiles,
  # this is not done by the global `nix.gc` option.
  home-manager.users."yoda" = { osConfig, config, pkgs, ... }: {
    nix.gc = {
      automatic = true;
      frequency = "weekly";
      options = "--delete-older-than 5d";
    };
  };
  home-manager.users."root" = { osConfig, config, pkgs, ... }: {
    nix.gc = {
      automatic = true;
      frequency = "weekly";
      options = "--delete-older-than 5d";
    };
  };
}