49 isConvertibleWithToString
52 showDeclPrefix = loc: decl: prefix:
53 " - option(s) with prefix `${showOption (loc ++ [prefix])}' in module `${decl._file}'";
54 showRawDecls = loc: decls:
59 (showDeclPrefix loc decl)
60 (attrNames decl.options)
65 /* See https://nixos.org/manual/nixpkgs/unstable/#module-system-lib-evalModules
66 or file://./../doc/module-system/module-system.chapter.md
68 !!! Please think twice before adding to this argument list! The more
69 that is specified here instead of in the modules themselves the harder
70 it is to transparently move a set of modules to be a submodule of another
71 config (as the proper arguments need to be replicated at each call to
72 evalModules) and the less declarative the module set is. */
73 evalModules = evalModulesArgs@
76 , # This should only be used for special arguments that need to be evaluated
77 # when resolving module structure (like in imports). For everything else,
78 # there's _module.args. If specialArgs.modulesPath is defined it will be
79 # used as the base path for disabledModules.
82 # A nominal type for modules. When set and non-null, this adds a check to
83 # make sure that only compatible modules are imported.
85 , # This would be remove in the future, Prefer _module.args option instead.
87 , # This would be remove in the future, Prefer _module.check option instead.
92 lib.warnIf (evalModulesArgs?args) "The args argument to evalModules is deprecated. Please set config._module.args instead."
93 lib.warnIf (evalModulesArgs?check) "The check argument to evalModules is deprecated. Please set config._module.check instead."
97 optional (evalModulesArgs?args) {
102 ++ optional (evalModulesArgs?check) {
104 _module.check = mkDefault check;
107 regularModules = modules ++ legacyModules;
109 # This internal module declare internal options under the `_module'
110 # attribute. These options are fragile, as they are used by the
111 # module system to change the interpretation of modules.
113 # When extended with extendModules or moduleType, a fresh instance of
114 # this module is used, to avoid conflicts and allow chaining of
116 internalModule = rec {
117 _file = "lib/modules.nix";
122 _module.args = mkOption {
123 # Because things like `mkIf` are entirely useless for
124 # `_module.args` (because there's no way modules can check which
125 # arguments were passed), we'll use `lazyAttrsOf` which drops
126 # support for that, in turn it's lazy in its values. This means e.g.
127 # a `_module.args.pkgs = import (fetchTarball { ... }) {}` won't
128 # start a download when `pkgs` wasn't evaluated.
129 type = types.lazyAttrsOf types.raw;
130 # Only render documentation once at the root of the option tree,
131 # not for all individual submodules.
132 # Allow merging option decls to make this internal regardless.
134 then null # unset => visible
135 else "internal"} = true;
136 # TODO: Change the type of this option to a submodule with a
137 # freeformType, so that individual arguments can be documented
140 Additional arguments passed to each module in addition to ones
141 like `lib`, `config`,
142 and `pkgs`, `modulesPath`.
144 This option is also available to all submodules. Submodules do not
145 inherit args from their parent module, nor do they provide args to
146 their parent module or sibling submodules. The sole exception to
147 this is the argument `name` which is provided by
148 parent modules to a submodule and contains the attribute name
149 the submodule is bound to, or a unique generated name if it is
150 not bound to an attribute.
152 Some arguments are already passed by default, of which the
153 following *cannot* be changed with this option:
154 - {var}`lib`: The nixpkgs library.
155 - {var}`config`: The results of all options after merging the values from all modules together.
156 - {var}`options`: The options declared in all modules.
157 - {var}`specialArgs`: The `specialArgs` argument passed to `evalModules`.
158 - All attributes of {var}`specialArgs`
160 Whereas option values can generally depend on other option values
161 thanks to laziness, this does not apply to `imports`, which
162 must be computed statically before anything else.
164 For this reason, callers of the module system can provide `specialArgs`
165 which are available during import resolution.
167 For NixOS, `specialArgs` includes
168 {var}`modulesPath`, which allows you to import
169 extra modules from the nixpkgs package tree without having to
170 somehow make the module aware of the location of the
171 `nixpkgs` or NixOS directories.
173 { modulesPath, ... }: {
175 (modulesPath + "/profiles/minimal.nix")
180 For NixOS, the default value for this option includes at least this argument:
181 - {var}`pkgs`: The nixpkgs package set according to
182 the {option}`nixpkgs.pkgs` option.
186 _module.check = mkOption {
190 description = "Whether to check whether all option definitions have matching declarations.";
193 _module.freeformType = mkOption {
194 type = types.nullOr types.optionType;
198 If set, merge all definitions that don't have an associated option
199 together using this type. The result then gets combined with the
200 values of all declared options to produce the final `
203 If this is `null`, definitions without an option
204 will throw an error unless {option}`_module.check` is
209 _module.specialArgs = mkOption {
213 Externally provided module arguments that can't be modified from
214 within a configuration, but can be used in module imports.
221 inherit extendModules;
224 _module.specialArgs = specialArgs;
229 let collected = collectModules
231 (specialArgs.modulesPath or "")
232 (regularModules ++ [ internalModule ])
233 ({ inherit lib options config specialArgs; } // specialArgs);
234 in mergeModules prefix (reverseList collected);
236 options = merged.matchedOptions;
241 # For definitions that have an associated option
242 declaredConfig = mapAttrsRecursiveCond (v: ! isOption v) (_: v: v.value) options;
244 # If freeformType is set, this is for definitions that don't have an associated option
249 value = setAttrByPath def.prefix def.value;
250 }) merged.unmatchedDefns;
251 in if defs == [] then {}
252 else declaredConfig._module.freeformType.merge prefix defs;
254 in if declaredConfig._module.freeformType == null then declaredConfig
255 # Because all definitions that had an associated option ended in
256 # declaredConfig, freeformConfig can only contain the non-option
257 # paths, meaning recursiveUpdate will never override any value
258 else recursiveUpdate freeformConfig declaredConfig;
261 if config._module.check && config._module.freeformType == null && merged.unmatchedDefns != [] then
263 firstDef = head merged.unmatchedDefns;
266 optText = showOption (prefix ++ firstDef.prefix);
268 builtins.addErrorContext
269 "while evaluating the error message for definitions for `${optText}', which is an option that does not exist"
270 (builtins.addErrorContext
271 "while evaluating a definition from `${firstDef.file}'"
272 ( showDefs [ firstDef ])
275 "The option `${optText}' does not exist. Definition values:${defText}";
277 if attrNames options == [ "_module" ]
278 # No options were declared at all (`_module` is built in)
279 # but we do have unmatched definitions, and no freeformType (earlier conditions)
282 optionName = showOption prefix;
288 It seems as if you're trying to declare an option by placing it into `config' rather than `options'!
294 However there are no options defined in `${showOption prefix}'. Are you sure you've
295 declared your options properly? This can happen if you e.g. declared your options in `types.submodule'
296 under `config' rather than `options'.
301 checked = builtins.seq checkUnmatched;
303 extendModules = extendArgs@{
308 evalModules (evalModulesArgs // {
310 modules = regularModules ++ modules;
311 specialArgs = evalModulesArgs.specialArgs or {} // specialArgs;
312 prefix = extendArgs.prefix or evalModulesArgs.prefix or [];
315 type = lib.types.submoduleWith {
316 inherit modules specialArgs class;
319 result = withWarnings {
320 _type = "configuration";
321 options = checked options;
322 config = checked (removeAttrs config [ "_module" ]);
323 _module = checked (config._module);
324 inherit extendModules type;
329 # collectModules :: (class: String) -> (modulesPath: String) -> (modules: [ Module ]) -> (args: Attrs) -> [ Module ]
331 # Collects all modules recursively through `import` statements, filtering out
332 # all modules in disabledModules.
333 collectModules = class: let
335 # Like unifyModuleSyntax, but also imports paths and calls functions if necessary
336 loadModule = args: fallbackFile: fallbackKey: m:
338 unifyModuleSyntax fallbackFile fallbackKey (applyModuleArgs fallbackKey m args)
339 else if isAttrs m then
340 if m._type or "module" == "module" then
341 unifyModuleSyntax fallbackFile fallbackKey m
342 else if m._type == "if" || m._type == "override" then
343 loadModule args fallbackFile fallbackKey { config = m; }
346 "Could not load a value as a module, because it is of type ${lib.strings.escapeNixString m._type}"
347 + lib.optionalString (fallbackFile != unknownModule) ", in file ${toString fallbackFile}."
348 + lib.optionalString (m._type == "configuration") " If you do intend to import this configuration, please only import the modules that make up the configuration. You may have to create a `let` binding, file or attribute to give yourself access to the relevant modules.\nWhile loading a configuration into the module system is a very sensible idea, it can not be done cleanly in practice."
349 # Extended explanation: That's because a finalized configuration is more than just a set of modules. For instance, it has its own `specialArgs` that, by the nature of `specialArgs` can't be loaded through `imports` or the the `modules` argument. So instead, we have to ask you to extract the relevant modules and use those instead. This way, we keep the module system comparatively simple, and hopefully avoid a bad surprise down the line.
351 else if isList m then
352 let defs = [{ file = fallbackFile; value = m; }]; in
353 throw "Module imports can't be nested lists. Perhaps you meant to remove one level of lists? Definitions: ${showDefs defs}"
354 else unifyModuleSyntax (toString m) (toString m) (applyModuleArgsIfFunction (toString m) (import m) args);
360 if m._class != null -> m._class == class
363 throw "The module ${m._file or m.key} was imported into ${class} instead of ${m._class}."
368 Collects all modules recursively into the form
371 disabled = [ <list of disabled modules> ];
372 # All modules of the main module list
376 module = <module for key1>;
377 # All modules imported by the module for key1
381 module = <module for key1-1>;
382 # All modules imported by the module for key1-1
392 collectStructuredModules =
394 collectResults = modules: {
395 disabled = concatLists (catAttrs "disabled" modules);
398 in parentFile: parentKey: initialModules: args: collectResults (imap1 (n: x:
400 module = checkModule (loadModule args parentFile "${parentKey}:anon-${toString n}" x);
401 collectedImports = collectStructuredModules module._file module.key module.imports args;
405 modules = collectedImports.modules;
406 disabled = (if module.disabledModules != [] then [{ file = module._file; disabled = module.disabledModules; }] else []) ++ collectedImports.disabled;
409 # filterModules :: String -> { disabled, modules } -> [ Module ]
411 # Filters a structure as emitted by collectStructuredModules by removing all disabled
412 # modules recursively. It returns the final list of unique-by-key modules
413 filterModules = modulesPath: { disabled, modules }:
418 if builtins.substring 0 1 m == "/"
420 else toString modulesPath + "/" + m
422 else if isConvertibleWithToString m
424 if m?key && m.key != toString m
426 throw "Module `${file}` contains a disabledModules item that is an attribute set that can be converted to a string (${toString m}) but also has a `.key` attribute (${m.key}) with a different value. This makes it ambiguous which module should be disabled."
435 then throw "Module `${file}` contains a disabledModules item that is an attribute set, presumably a module, that does not have a `key` attribute. This means that the module system doesn't have any means to identify the module that should be disabled. Make sure that you've put the correct value in disabledModules: a string path relative to modulesPath, a path value, or an attribute set with a `key` attribute."
436 else throw "Each disabledModules item must be a path, string, or a attribute set with a key attribute, or a value supported by toString. However, one of the disabledModules items in `${toString file}` is none of that, but is of type ${builtins.typeOf m}.";
438 disabledKeys = concatMap ({ file, disabled }: map (moduleKey file) disabled) disabled;
439 keyFilter = filter (attrs: ! elem attrs.key disabledKeys);
440 in map (attrs: attrs.module) (builtins.genericClosure {
441 startSet = keyFilter modules;
442 operator = attrs: keyFilter attrs.modules;
445 in modulesPath: initialModules: args:
446 filterModules modulesPath (collectStructuredModules unknownModule "" initialModules args);
448 /* Wrap a module with a default location for reporting errors. */
449 setDefaultModuleLocation = file: m:
450 { _file = file; imports = [ m ]; };
452 /* Massage a module into canonical form, that is, a set consisting
453 of ‘options’, ‘config’ and ‘imports’ attributes. */
454 unifyModuleSyntax = file: key: m:
456 addMeta = config: if m ? meta
457 then mkMerge [ config { meta = m.meta; } ]
459 addFreeformType = config: if m ? freeformType
460 then mkMerge [ config { _module.freeformType = m.freeformType; } ]
463 if m ? config || m ? options then
464 let badAttrs = removeAttrs m ["_class" "_file" "key" "disabledModules" "imports" "options" "config" "meta" "freeformType"]; in
465 if badAttrs != {} then
466 throw "Module `${key}' has an unsupported attribute `${head (attrNames badAttrs)}'. This is caused by introducing a top-level `config' or `options' attribute. Add configuration attributes immediately on the top level instead, or move all of them (namely: ${toString (attrNames badAttrs)}) into the explicit `config' attribute."
468 { _file = toString m._file or file;
469 _class = m._class or null;
470 key = toString m.key or key;
471 disabledModules = m.disabledModules or [];
472 imports = m.imports or [];
473 options = m.options or {};
474 config = addFreeformType (addMeta (m.config or {}));
478 lib.throwIfNot (isAttrs m) "module ${file} (${key}) does not look like a module."
479 { _file = toString m._file or file;
480 _class = m._class or null;
481 key = toString m.key or key;
482 disabledModules = m.disabledModules or [];
483 imports = m.require or [] ++ m.imports or [];
485 config = addFreeformType (removeAttrs m ["_class" "_file" "key" "disabledModules" "require" "imports" "freeformType"]);
488 applyModuleArgsIfFunction = key: f: args@{ config, options, lib, ... }:
489 if isFunction f then applyModuleArgs key f args else f;
491 applyModuleArgs = key: f: args@{ config, options, lib, ... }:
493 # Module arguments are resolved in a strict manner when attribute set
494 # deconstruction is used. As the arguments are now defined with the
495 # config._module.args option, the strictness used on the attribute
496 # set argument would cause an infinite loop, if the result of the
497 # option is given as argument.
499 # To work-around the strictness issue on the deconstruction of the
500 # attributes set argument, we create a new attribute set which is
501 # constructed to satisfy the expected set of attributes. Thus calling
502 # a module will resolve strictly the attributes used as argument but
503 # not their values. The values are forwarding the result of the
504 # evaluation of the option.
505 context = name: ''while evaluating the module argument `${name}' in "${key}":'';
506 extraArgs = builtins.mapAttrs (name: _:
507 builtins.addErrorContext (context name)
508 (args.${name} or config._module.args.${name})
509 ) (lib.functionArgs f);
511 # Note: we append in the opposite order such that we can add an error
512 # context on the explicit arguments of "args" too. This update
513 # operator is used to make the "args@{ ... }: with args.lib;" notation
515 in f (args // extraArgs);
517 /* Merge a list of modules. This will recurse over the option
518 declarations in all modules, combining them into a single set.
519 At the same time, for each option declaration, it will merge the
520 corresponding option definitions in all machines, returning them
521 in the ‘value’ attribute of each option.
523 This returns a set like
525 # A recursive set of options along with their final values
527 foo = { _type = "option"; value = "option value of foo"; ... };
528 bar.baz = { _type = "option"; value = "option value of bar.baz"; ... };
531 # A list of definitions that weren't matched by any option
533 { file = "file.nix"; prefix = [ "qux" ]; value = "qux"; }
538 mergeModules = prefix: modules:
539 mergeModules' prefix modules
540 (concatMap (m: map (config: { file = m._file; inherit config; }) (pushDownProperties m.config)) modules);
542 mergeModules' = prefix: modules: configs:
544 # an attrset 'name' => list of submodules that declare ‘name’.
549 (module: let subtree = module.options; in
550 if !(builtins.isAttrs subtree) then
552 An option declaration for `${builtins.concatStringsSep "." prefix}' has type
553 `${builtins.typeOf subtree}' rather than an attribute set.
554 Did you mean to define this outside of `options'?
559 [{ inherit (module) _file; pos = builtins.unsafeGetAttrPos n subtree; options = option; }]
565 # The root of any module definition must be an attrset.
570 # TODO: I have my doubts that this error would occur when option definitions are not matched.
571 # The implementation of this check used to be tied to a superficially similar check for
572 # options, so maybe that's why this is here.
573 isAttrs c.config || throw ''
574 In module `${c.file}', you're trying to define a value of type `${builtins.typeOf c.config}'
575 rather than an attribute set for the option
576 `${builtins.concatStringsSep "." prefix}'!
578 This usually happens if `${builtins.concatStringsSep "." prefix}' has option
579 definitions inside that are not matched. Please check how to properly define
580 this option by e.g. referring to `man 5 configuration.nix'!
586 # an attrset 'name' => list of submodules that define ‘name’.
587 pushedDownDefinitionsByName =
594 map (config: { inherit (module) file; inherit config; }) (pushDownProperties value)
599 # extract the definitions for each loc
600 rawDefinitionsByName =
607 [{ inherit (module) file; inherit value; }]
613 # Convert an option tree decl to a submodule option decl
614 optionTreeToOption = decl:
615 if isOption decl.options
619 type = types.submoduleWith {
620 modules = [ { options = decl.options; } ];
621 # `null` is not intended for use by modules. It is an internal
622 # value that means "whatever the user has declared elsewhere".
623 # This might become obsolete with https://github.com/NixOS/nixpkgs/issues/162398
624 shorthandOnlyDefinesConfig = null;
629 resultsByName = mapAttrs (name: decls:
630 # We're descending into attribute ‘name’.
632 loc = prefix ++ [name];
633 defns = pushedDownDefinitionsByName.${name} or [];
634 defns' = rawDefinitionsByName.${name} or [];
637 && (m.options._type == "option"
638 || throwDeclarationTypeError loc m.options._type m._file
643 if length optionDecls == length decls then
644 let opt = fixupOptionType loc (mergeOptionDecls loc decls);
646 matchedOptions = evalOptionValue loc opt defns';
649 else if optionDecls != [] then
650 if all (x: x.options.type.name or null == "submodule") optionDecls
651 # Raw options can only be merged into submodules. Merging into
652 # attrsets might be nice, but ambiguous. Suppose we have
653 # attrset as a `attrsOf submodule`. User declares option
654 # attrset.foo.bar, this could mean:
655 # a. option `bar` is only available in `attrset.foo`
656 # b. option `foo.bar` is available in all `attrset.*`
657 # c. reject and require "<name>" as a reminder that it behaves like (b).
658 # d. magically combine (a) and (c).
659 # All of the above are merely syntax sugar though.
661 let opt = fixupOptionType loc (mergeOptionDecls loc (map optionTreeToOption decls));
663 matchedOptions = evalOptionValue loc opt defns';
668 nonOptions = filter (m: !isOption m.options) decls;
670 throw "The option `${showOption loc}' in module `${(lib.head optionDecls)._file}' would be a parent of the following options, but its type `${(lib.head optionDecls).options.type.description or "<no description>"}' does not support nested options.\n${
671 showRawDecls loc nonOptions
674 mergeModules' loc decls defns) declsByName;
676 matchedOptions = mapAttrs (n: v: v.matchedOptions) resultsByName;
678 # an attrset 'name' => list of unmatched definitions for 'name'
679 unmatchedDefnsByName =
680 # Propagate all unmatched definitions from nested option sets
681 mapAttrs (n: v: v.unmatchedDefns) resultsByName
682 # Plus the definitions for the current prefix that don't have a matching option
683 // removeAttrs rawDefinitionsByName (attrNames matchedOptions);
685 inherit matchedOptions;
687 # Transforms unmatchedDefnsByName into a list of definitions
691 # When no config values exist, there can be no unmatched config, so
692 # we short circuit and avoid evaluating more _options_ than necessary.
695 concatLists (mapAttrsToList (name: defs:
697 # Set this so we know when the definition first left unmatched territory
698 prefix = [name] ++ (def.prefix or []);
700 ) unmatchedDefnsByName);
703 throwDeclarationTypeError = loc: actualTag: file:
705 name = lib.strings.escapeNixIdentifier (lib.lists.last loc);
706 path = showOption loc;
710 "In module ${file}: expected an option declaration at option path `${path}` but got an attribute set with type ${actualTag}"
711 ] ++ optional (actualTag == "option-type") ''
712 When declaring an option, you must wrap the type in a `mkOption` call. It should look somewhat like:
714 ${name} = lib.mkOption {
716 type = <the type you wrote for ${name}>;
721 # Ideally we'd know the exact syntax they used, but short of that,
722 # we can only reliably repeat the last. However, we repeat the
723 # full path in a non-misleading way here, in case they overlook
724 # the start of the message. Examples attract attention.
725 comment = optionalString (depth > 1) "\n # ${showOption loc}";
727 throw (concatStringsSep "\n\n" paragraphs);
729 /* Merge multiple option declarations into a single declaration. In
730 general, there should be only one declaration of each option.
731 The exception is the ‘options’ attribute, which specifies
732 sub-options. These can be specified multiple times to allow one
733 module to add sub-options to an option declared somewhere else
734 (e.g. multiple modules define sub-options for ‘fileSystems’).
736 'loc' is the list of attribute names where the option is located.
738 'opts' is a list of modules. Each module has an options attribute which
739 correspond to the definition of 'loc' in 'opt.file'. */
744 t' = opt.options.type;
745 mergedType = t.typeMerge t'.functor;
746 typesMergeable = mergedType != null;
747 typeSet = if (bothHave "type") && typesMergeable
748 then { type = mergedType; }
750 bothHave = k: opt.options ? ${k} && res ? ${k};
752 if bothHave "default" ||
753 bothHave "example" ||
754 bothHave "description" ||
756 (bothHave "type" && (! typesMergeable))
758 throw "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
761 getSubModules = opt.options.type.getSubModules or null;
763 if getSubModules != null then map (setDefaultModuleLocation opt._file) getSubModules ++ res.options
765 in opt.options // res //
766 { declarations = res.declarations ++ [opt._file];
767 # In the case of modules that are generated dynamically, we won't
768 # have exact declaration lines; fall back to just the file being
770 declarationPositions = res.declarationPositions
771 ++ (if opt.pos != null
773 else [{ file = opt._file; line = null; column = null; }]);
774 options = submodules;
776 ) { inherit loc; declarations = []; declarationPositions = []; options = []; } opts;
778 /* Merge all the definitions of an option to produce the final
780 evalOptionValue = loc: opt: defs:
782 # Add in the default value for this option, if any.
784 (optional (opt ? default)
785 { file = head opt.declarations; value = mkOptionDefault opt.default; }) ++ defs;
787 # Handle properties, check types, and merge everything together.
789 if opt.readOnly or false && length defs' > 1 then
791 # For a better error message, evaluate all readOnly definitions as
792 # if they were the only definition.
793 separateDefs = map (def: def // {
794 value = (mergeDefinitions loc opt.type [ def ]).mergedValue;
796 in throw "The option `${showOption loc}' is read-only, but it's set multiple times. Definition values:${showDefs separateDefs}"
798 mergeDefinitions loc opt.type defs';
800 # Apply the 'apply' function to the merged value. This allows options to
801 # yield a value computed from the definitions
802 value = if opt ? apply then opt.apply res.mergedValue else res.mergedValue;
805 warnIf (opt.type.deprecationMessage != null)
806 "The type `types.${opt.type.name}' of option `${showOption loc}' defined in ${showFiles opt.declarations} is deprecated. ${opt.type.deprecationMessage}";
808 in warnDeprecation opt //
809 { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
810 inherit (res.defsFinal') highestPrio;
811 definitions = map (def: def.value) res.defsFinal;
812 files = map (def: def.file) res.defsFinal;
813 definitionsWithLocations = res.defsFinal;
814 inherit (res) isDefined;
815 # This allows options to be correctly displayed using `${options.path.to.it}`
816 __toString = _: showOption loc;
819 # Merge definitions of a value of a given type.
820 mergeDefinitions = loc: type: defs: rec {
823 # Process mkMerge and mkIf properties.
824 defs' = concatMap (m:
825 map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))
828 # Process mkOverride properties.
829 defs'' = filterOverrides' defs';
831 # Sort mkOrder properties.
833 # Avoid sorting if we don't have to.
834 if any (def: def.value._type or "" == "order") defs''.values
835 then sortProperties defs''.values
839 inherit (defs'') highestPrio;
841 defsFinal = defsFinal'.values;
843 # Type-check the remaining definitions, and merge them. Or throw if no definitions.
846 if all (def: type.check def.value) defsFinal then type.merge loc defsFinal
847 else let allInvalid = filter (def: ! type.check def.value) defsFinal;
848 in throw "A definition for option `${showOption loc}' is not of type `${type.description}'. Definition values:${showDefs allInvalid}"
850 # (nixos-option detects this specific error message and gives it special
851 # handling. If changed here, please change it there too.)
852 throw "The option `${showOption loc}' is used but not defined.";
854 isDefined = defsFinal != [];
857 if isDefined then { value = mergedValue; }
861 /* Given a config set, expand mkMerge properties, and push down the
862 other properties into the children. The result is a list of
863 config sets that do not have properties at top-level. For
866 mkMerge [ { boot = set1; } (mkIf cond { boot = set2; services = set3; }) ]
870 [ { boot = set1; } { boot = mkIf cond set2; services = mkIf cond set3; } ].
872 This transform is the critical step that allows mkIf conditions
873 to refer to the full configuration without creating an infinite
876 pushDownProperties = cfg:
877 if cfg._type or "" == "merge" then
878 concatMap pushDownProperties cfg.contents
879 else if cfg._type or "" == "if" then
880 map (mapAttrs (n: v: mkIf cfg.condition v)) (pushDownProperties cfg.content)
881 else if cfg._type or "" == "override" then
882 map (mapAttrs (n: v: mkOverride cfg.priority v)) (pushDownProperties cfg.content)
883 else # FIXME: handle mkOrder?
886 /* Given a config value, expand mkMerge properties, and discharge
887 any mkIf conditions. That is, this is the place where mkIf
888 conditions are actually evaluated. The result is a list of
889 config values. For example, ‘mkIf false x’ yields ‘[]’,
890 ‘mkIf true x’ yields ‘[x]’, and
892 mkMerge [ 1 (mkIf true 2) (mkIf true (mkIf false 3)) ]
896 dischargeProperties = def:
897 if def._type or "" == "merge" then
898 concatMap dischargeProperties def.contents
899 else if def._type or "" == "if" then
900 if isBool def.condition then
901 if def.condition then
902 dischargeProperties def.content
906 throw "‘mkIf’ called with a non-Boolean condition"
910 /* Given a list of config values, process the mkOverride properties,
911 that is, return the values that have the highest (that is,
912 numerically lowest) priority, and strip the mkOverride
913 properties. For example,
915 [ { file = "/1"; value = mkOverride 10 "a"; }
916 { file = "/2"; value = mkOverride 20 "b"; }
917 { file = "/3"; value = "z"; }
918 { file = "/4"; value = mkOverride 10 "d"; }
923 [ { file = "/1"; value = "a"; }
924 { file = "/4"; value = "d"; }
927 Note that "z" has the default priority 100.
929 filterOverrides = defs: (filterOverrides' defs).values;
931 filterOverrides' = defs:
933 getPrio = def: if def.value._type or "" == "override" then def.value.priority else defaultOverridePriority;
934 highestPrio = foldl' (prio: def: min (getPrio def) prio) 9999 defs;
935 strip = def: if def.value._type or "" == "override" then def // { value = def.value.content; } else def;
937 values = concatMap (def: if getPrio def == highestPrio then [(strip def)] else []) defs;
941 /* Sort a list of properties. The sort priority of a property is
942 defaultOrderPriority by default, but can be overridden by wrapping the property
944 sortProperties = defs:
947 if def.value._type or "" == "order"
948 then def // { value = def.value.content; inherit (def.value) priority; }
950 defs' = map strip defs;
951 compare = a: b: (a.priority or defaultOrderPriority) < (b.priority or defaultOrderPriority);
952 in sort compare defs';
954 # This calls substSubModules, whose entire purpose is only to ensure that
955 # option declarations in submodules have accurate position information.
956 # TODO: Merge this into mergeOptionDecls
957 fixupOptionType = loc: opt:
958 if opt.type.getSubModules or null == null
959 then opt // { type = opt.type or types.unspecified; }
960 else opt // { type = opt.type.substSubModules opt.options; options = []; };
964 Merge an option's definitions in a way that preserves the priority of the
965 individual attributes in the option value.
967 This does not account for all option semantics, such as readOnly.
970 option -> attrsOf { highestPrio, value }
972 mergeAttrDefinitionsWithPrio = opt:
980 (lib.mapAttrsToList (k: value: { ${k} = def // { inherit value; }; }))
981 (pushDownProperties value)
983 opt.definitionsWithLocations
987 assert opt.type.name == "attrsOf" || opt.type.name == "lazyAttrsOf";
990 let merging = lib.mergeDefinitions (opt.loc ++ [k]) opt.type.nestedTypes.elemType v;
992 value = merging.mergedValue;
993 inherit (merging.defsFinal') highestPrio;
999 mkIf = condition: content:
1001 inherit condition content;
1004 mkAssert = assertion: message: content:
1006 (if assertion then true else throw "\nFailed assertion: ${message}")
1014 mkOverride = priority: content:
1015 { _type = "override";
1016 inherit priority content;
1019 mkOptionDefault = mkOverride 1500; # priority of option defaults
1020 mkDefault = mkOverride 1000; # used in config sections of non-user modules to set a default
1021 defaultOverridePriority = 100;
1022 mkImageMediaOverride = mkOverride 60; # image media profiles can be derived by inclusion into host config, hence needing to override host config, but do allow user to mkForce
1023 mkForce = mkOverride 50;
1024 mkVMOverride = mkOverride 10; # used by ‘nixos-rebuild build-vm’
1026 defaultPriority = lib.warnIf (lib.isInOldestRelease 2305) "lib.modules.defaultPriority is deprecated, please use lib.modules.defaultOverridePriority instead." defaultOverridePriority;
1028 mkFixStrictness = lib.warn "lib.mkFixStrictness has no effect and will be removed. It returns its argument unmodified, so you can just remove any calls." id;
1030 mkOrder = priority: content:
1032 inherit priority content;
1035 mkBefore = mkOrder 500;
1036 defaultOrderPriority = 1000;
1037 mkAfter = mkOrder 1500;
1039 # Convenient property used to transfer all definitions and their
1040 # properties from one option to another. This property is useful for
1041 # renaming options, and also for including properties from another module
1042 # system, including sub-modules.
1044 # { config, options, ... }:
1047 # # 'bar' might not always be defined in the current module-set.
1048 # config.foo.enable = mkAliasDefinitions (options.bar.enable or {});
1050 # # 'barbaz' has to be defined in the current module-set.
1051 # config.foobar.paths = mkAliasDefinitions options.barbaz.paths;
1054 # Note, this is different than taking the value of the option and using it
1055 # as a definition, as the new definition will not keep the mkOverride /
1056 # mkDefault properties of the previous option.
1058 mkAliasDefinitions = mkAliasAndWrapDefinitions id;
1059 mkAliasAndWrapDefinitions = wrap: option:
1060 mkAliasIfDef option (wrap (mkMerge option.definitions));
1062 # Similar to mkAliasAndWrapDefinitions but copies over the priority from the
1065 # If a priority is not set, it assumes a priority of defaultOverridePriority.
1066 mkAliasAndWrapDefsWithPriority = wrap: option:
1068 prio = option.highestPrio or defaultOverridePriority;
1069 defsWithPrio = map (mkOverride prio) option.definitions;
1070 in mkAliasIfDef option (wrap (mkMerge defsWithPrio));
1072 mkAliasIfDef = option:
1073 mkIf (isOption option && option.isDefined);
1075 /* Compatibility. */
1076 fixMergeModules = modules: args: evalModules { inherit modules args; check = false; };
1079 /* Return a module that causes a warning to be shown if the
1080 specified option is defined. For example,
1082 mkRemovedOptionModule [ "boot" "loader" "grub" "bootDevice" ] "<replacement instructions>"
1084 causes a assertion if the user defines boot.loader.grub.bootDevice.
1086 replacementInstructions is a string that provides instructions on
1087 how to achieve the same functionality without the removed option,
1088 or alternatively a reasoning why the functionality is not needed.
1089 replacementInstructions SHOULD be provided!
1091 mkRemovedOptionModule = optionName: replacementInstructions:
1093 { options = setAttrByPath optionName (mkOption {
1095 apply = x: throw "The option `${showOption optionName}' can no longer be used since it's been removed. ${replacementInstructions}";
1098 let opt = getAttrFromPath optionName options; in [{
1099 assertion = !opt.isDefined;
1101 The option definition `${showOption optionName}' in ${showFiles opt.files} no longer has any effect; please remove it.
1102 ${replacementInstructions}
1107 /* Return a module that causes a warning to be shown if the
1108 specified "from" option is defined; the defined value is however
1109 forwarded to the "to" option. This can be used to rename options
1110 while providing backward compatibility. For example,
1112 mkRenamedOptionModule [ "boot" "copyKernels" ] [ "boot" "loader" "grub" "copyKernels" ]
1114 forwards any definitions of boot.copyKernels to
1115 boot.loader.grub.copyKernels while printing a warning.
1117 This also copies over the priority from the aliased option to the
1120 mkRenamedOptionModule = from: to: doRename {
1124 use = builtins.trace "Obsolete option `${showOption from}' is used. It was renamed to `${showOption to}'.";
1127 mkRenamedOptionModuleWith = {
1128 /* Old option path as list of strings. */
1130 /* New option path as list of strings. */
1134 Release number of the first release that contains the rename, ignoring backports.
1135 Set it to the upcoming release, matching the nixpkgs/.version file.
1142 warn = lib.isInOldestRelease sinceRelease;
1143 use = lib.warnIf (lib.isInOldestRelease sinceRelease)
1144 "Obsolete option `${showOption from}' is used. It was renamed to `${showOption to}'.";
1147 /* Return a module that causes a warning to be shown if any of the "from"
1148 option is defined; the defined values can be used in the "mergeFn" to set
1150 This function can be used to merge multiple options into one that has a
1153 "mergeFn" takes the module "config" as a parameter and must return a value
1154 of "to" option type.
1156 mkMergedOptionModule
1161 let value = p: getAttrFromPath p config;
1163 if (value [ "a" "b" "c" ]) == true then "foo"
1164 else if (value [ "d" "e" "f" ]) == true then "bar"
1167 - options.a.b.c is a removed boolean option
1168 - options.d.e.f is a removed boolean option
1169 - options.x.y.z is a new str option that combines a.b.c and d.e.f
1172 This show a warning if any a.b.c or d.e.f is set, and set the value of
1173 x.y.z to the result of the merge function
1175 mkMergedOptionModule = from: to: mergeFn:
1176 { config, options, ... }:
1178 options = foldl' recursiveUpdate {} (map (path: setAttrByPath path (mkOption {
1180 # To use the value in mergeFn without triggering errors
1181 default = "_mkMergedOptionModule";
1185 warnings = filter (x: x != "") (map (f:
1186 let val = getAttrFromPath f config;
1187 opt = getAttrFromPath f options;
1190 (val != "_mkMergedOptionModule")
1191 "The option `${showOption f}' defined in ${showFiles opt.files} has been changed to `${showOption to}' that has a different type. Please read `${showOption to}' documentation and update your configuration accordingly."
1193 } // setAttrByPath to (mkMerge
1195 (any (f: (getAttrFromPath f config) != "_mkMergedOptionModule") from)
1199 /* Single "from" version of mkMergedOptionModule.
1200 Return a module that causes a warning to be shown if the "from" option is
1201 defined; the defined value can be used in the "mergeFn" to set the "to"
1203 This function can be used to change an option into another that has a
1206 "mergeFn" takes the module "config" as a parameter and must return a value of
1209 mkChangedOptionModule [ "a" "b" "c" ] [ "x" "y" "z" ]
1211 let value = getAttrFromPath [ "a" "b" "c" ] config;
1213 if value > 100 then "high"
1216 - options.a.b.c is a removed int option
1217 - options.x.y.z is a new str option that supersedes a.b.c
1219 This show a warning if a.b.c is set, and set the value of x.y.z to the
1220 result of the change function
1222 mkChangedOptionModule = from: to: changeFn:
1223 mkMergedOptionModule [ from ] to changeFn;
1225 /* Like ‘mkRenamedOptionModule’, but doesn't show a warning. */
1226 mkAliasOptionModule = from: to: doRename {
1233 /* Transitional version of mkAliasOptionModule that uses MD docs.
1235 This function is no longer necessary and merely an alias of `mkAliasOptionModule`.
1237 mkAliasOptionModuleMD = mkAliasOptionModule;
1239 /* mkDerivedConfig : Option a -> (a -> Definition b) -> Definition b
1241 Create config definitions with the same priority as the definition of another option.
1242 This should be used for option definitions where one option sets the value of another as a convenience.
1243 For instance a config file could be set with a `text` or `source` option, where text translates to a `source`
1244 value using `mkDerivedConfig options.text (pkgs.writeText "filename.conf")`.
1246 It takes care of setting the right priority using `mkOverride`.
1248 # TODO: make the module system error message include information about `opt` in
1249 # error messages about conflicts. E.g. introduce a variation of `mkOverride` which
1250 # adds extra location context to the definition object. This will allow context to be added
1251 # to all messages that report option locations "this value was derived from <full option name>
1252 # which was defined in <locations>". It can provide a trace of options that contributed
1254 mkDerivedConfig = opt: f:
1256 (opt.highestPrio or defaultOverridePriority)
1260 Return a module that help declares an option that has been renamed.
1261 When a value is defined for the old option, it is forwarded to the `to` option.
1264 # List of strings representing the attribute path of the old option.
1266 # List of strings representing the attribute path of the new option.
1268 # Boolean, whether the old option is to be included in documentation.
1270 # Whether to warn when a value is defined for the old option.
1271 # NOTE: This requires the NixOS assertions module to be imported, so
1272 # - this generally does not work in submodules
1273 # - this may or may not work outside NixOS
1275 # A function that is applied to the option value, to form the value
1276 # of the old `from` option.
1278 # For example, the identity function can be passed, to return the option value unchanged.
1283 # To add a warning, you can pass the partially applied `warn` function.
1285 # use = lib.warn "Obsolete option `${opt.old}' is used. Use `${opt.to}' instead.";
1288 # Legacy option, enabled by default: whether to preserve the priority of definitions in `old`.
1289 withPriority ? true,
1290 # A boolean that defines the `mkIf` condition for `to`.
1291 # If the condition evaluates to `true`, and the `to` path points into an
1292 # `attrsOf (submodule ...)`, then `doRename` would cause an empty module to
1293 # be created, even if the `from` option is undefined.
1294 # By setting this to an expression that may return `false`, you can inhibit
1295 # this undesired behavior.
1300 # { config, lib, ... }:
1302 # inherit (lib) mkOption mkEnableOption types doRename;
1308 # services.foo.enable = mkEnableOption "foo";
1310 # # New multi-instance service
1311 # services.foos = mkOption {
1312 # type = types.attrsOf (types.submodule …);
1317 # from = [ "services" "foo" "bar" ];
1318 # to = [ "services" "foos" "" "bar" ];
1322 # withPriority = true;
1323 # # Only define services.foos."" if needed. (It's not just about `bar`)
1324 # condition = config.services.foo.enable;
1331 { config, options, ... }:
1333 fromOpt = getAttrFromPath from options;
1334 toOf = attrByPath to
1335 (abort "Renaming error: option `${showOption to}' does not exist.");
1336 toType = let opt = attrByPath to {} options; in opt.type or (types.submodule {});
1339 options = setAttrByPath from (mkOption {
1341 description = "Alias of {option}`${showOption to}`.";
1342 apply = x: use (toOf config);
1343 } // optionalAttrs (toType != null) {
1346 config = mkIf condition (mkMerge [
1347 (optionalAttrs (options ? warnings) {
1348 warnings = optional (warn && fromOpt.isDefined)
1349 "The option `${showOption from}' defined in ${showFiles fromOpt.files} has been renamed to `${showOption to}'.";
1352 then mkAliasAndWrapDefsWithPriority (setAttrByPath to) fromOpt
1353 else mkAliasAndWrapDefinitions (setAttrByPath to) fromOpt)
1357 /* Use this function to import a JSON file as NixOS configuration.
1359 modules.importJSON :: path -> attrs
1361 importJSON = file: {
1363 config = lib.importJSON file;
1366 /* Use this function to import a TOML file as NixOS configuration.
1368 modules.importTOML :: path -> attrs
1370 importTOML = file: {
1372 config = lib.importTOML file;
1375 private = lib.mapAttrs
1376 (k: lib.warn "External use of `lib.modules.${k}` is deprecated. If your use case isn't covered by non-deprecated functions, we'd like to know more and perhaps support your use case well, instead of providing access to these low level functions. In this case please open an issue in https://github.com/nixos/nixpkgs/issues/.")
1379 applyModuleArgsIfFunction
1386 collectModules = collectModules null;
1392 # NOTE: not all of these functions are necessarily public interfaces; some
1393 # are just needed by types.nix, but are not meant to be consumed
1396 defaultOrderPriority
1397 defaultOverridePriority
1401 evalOptionValue # for use by lib.types
1405 fixupOptionType # should be private?
1409 mergeAttrDefinitionsWithPrio
1410 mergeOptionDecls # should be private?
1412 mkAliasAndWrapDefinitions
1413 mkAliasAndWrapDefsWithPriority
1417 mkAliasOptionModuleMD
1420 mkChangedOptionModule
1426 mkImageMediaOverride
1428 mkMergedOptionModule
1432 mkRemovedOptionModule
1433 mkRenamedOptionModule
1434 mkRenamedOptionModuleWith
1436 setDefaultModuleLocation