nixos-options

name	nixos-options
description	Skill for evaluating, searching, and inspecting authoritative NixOS options from local nixpkgs using nix eval.

Querying NixOS Options via nix eval

When reverse-engineering system settings into NixOS configuration options, query local nixpkgs directly to discover precise option names, types, and defaults.

1. List Sub-Attributes of an Option Path

nix eval --json --impure --expr '
  let
    eval = import <nixpkgs/nixos/lib/eval-config.nix> { modules = []; };
  in builtins.attrNames eval.options.<attribute.path>
'

Example:

nix eval --json --impure --expr 'let eval = import <nixpkgs/nixos/lib/eval-config.nix> { modules = []; }; in builtins.attrNames eval.options.security.pam'

---

2. List Sub-Options of Dynamic Sets (e.g. services.<name>, luks.devices.<name>)

nix eval --json --impure --expr '
  let
    eval = import <nixpkgs/nixos/lib/eval-config.nix> { modules = []; };
  in builtins.attrNames (eval.options.<attribute.path>.type.getSubOptions [])
'

---

3. Inspect Full Metadata (Type, Default, Description) for an Option

nix eval --json --impure --expr '
  let
    eval = import <nixpkgs/nixos/lib/eval-config.nix> { modules = []; };
    opt = eval.options.<attribute.path>.<option_name>;
  in {
    type = opt.type.name;
    description = opt.description or null;
    default = opt.default or null;
  }
'