1 { configuration ? import ../lib/from-env.nix "NIXOS_CONFIG" <nixos-config>
3 # provide an option name, as a string literal.
6 # provide a list of option names, as string literals.
10 # This file is made to be used as follow:
12 # $ nix-instantiate ./option-usage.nix --argstr testOption service.xserver.enable -A txtContent --eval
16 # $ nix-build ./option-usage.nix --argstr testOption service.xserver.enable -A txt -o service.xserver.enable._txt
18 # Other targets exists such as `dotContent`, `dot`, and `pdf`. If you are
19 # looking for the option usage of multiple options, you can provide a list
22 # $ nix-build ./option-usage.nix --arg testOptions \
23 # '["boot.loader.gummiboot.enable" "boot.loader.gummiboot.timeout"]' \
24 # -A txt -o gummiboot.list
26 # Note, this script is slow as it has to evaluate all options of the system
27 # once per queried option.
29 # This nix expression works by doing a first evaluation, which evaluates the
30 # result of every option.
32 # Then, for each queried option, we evaluate the NixOS modules a second
33 # time, except that we replace the `config` argument of all the modules with
34 # the result of the original evaluation, except for the tested option which
35 # value is replaced by a `throw` statement which is caught by the `tryEval`
36 # evaluation of each option value.
38 # We then compare the result of the evaluation of the original module, with
39 # the result of the second evaluation, and consider that the new failures are
40 # caused by our mutation of the `config` argument.
42 # Doing so returns all option results which are directly using the
43 # tested option result.
45 with import ../../lib;
51 }: import ../lib/eval-config.nix {
52 modules = [ configuration ];
59 excludedTestOptions = [
60 # We cannot evluate _module.args, as it is used during the computation
61 # of the modules list.
64 # For some reasons which we yet have to investigate, some options cannot
65 # be replaced by a throw without causing a non-catchable failure.
68 "networking.interfaces"
72 "services.openssh.startWhenNeeded"
75 # for some reasons which we yet have to investigate, some options are
76 # time-consuming to compute, thus we filter them out at the moment.
78 "boot.systemd.services"
82 excludeOptions = list:
83 filter (opt: !(elem (showOption opt.loc) excludedOptions)) list;
86 reportNewFailures = old: new:
90 !(fst.success -> snd.success)
95 /* assert fst.name == snd.name; */ snd.name
98 # Use tryEval (strict ...) to know if there is any failure while
99 # evaluating the option value.
101 # Note, the `strict` function is not strict enough, but using toXML
102 # builtins multiply by 4 the memory usage and the time used to compute
104 tryCollectOptions = moduleResult:
105 forEach (excludeOptions (collect isOption moduleResult)) (opt:
106 { name = showOption opt.loc; } // builtins.tryEval (strict opt.value));
110 zipLists (tryCollectOptions old) (tryCollectOptions new)
115 # Create a list of modules where each module contains only one failling
117 introspectionModules =
119 setIntrospection = opt: rec {
120 name = showOption opt.loc;
122 config = setAttrByPath path
123 (throw "Usage introspection of '${name}' by forced failure.");
126 map setIntrospection (collect isOption eval.options);
128 overrideConfig = thrower:
129 recursiveUpdateUntil (path: old: new:
131 ) eval.config thrower.config;
136 option = thrower.name;
137 usedBy = assert __trace "Investigate ${thrower.name}" true;
138 reportNewFailures eval.options (evalFun {
140 config = overrideConfig thrower;
143 }) introspectionModules;
145 displayOptionsGraph =
148 if testOption != null then [ testOption ]
150 checkAll = checkList == [];
152 flip filter graph ({option, ...}:
153 (checkAll || elem option checkList)
154 && !(elem option excludedTestOptions)
157 graphToDot = graph: ''
158 digraph "Option Usages" {
159 ${concatMapStrings ({option, usedBy}:
160 concatMapStrings (user: ''
161 "${option}" -> "${user}"''
163 ) displayOptionsGraph}
168 concatMapStrings ({usedBy, ...}:
169 concatMapStrings (user: ''
172 ) displayOptionsGraph;
177 dotContent = graphToDot graph;
178 dot = pkgs.writeTextFile {
179 name = "option_usages.dot";
183 pdf = pkgs.texFunctions.dot2pdf {
187 txtContent = graphToText graph;
188 txt = pkgs.writeTextFile {
189 name = "option_usages.txt";