nixpkgs/lib/modules.nix

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Convert libs to a fixed-point This does break the API of being able to import any lib file and get its libs, however I'm not sure people did this. I made this while exploring being able to swap out docFn with a stub in #2305, to avoid functor performance problems. I don't know if that is going to move forward (or if it is a problem or not,) but after doing all this work figured I'd put it up anyway :) Two notable advantages to this approach: 1. when a lib inherits another lib's functions, it doesn't automatically get put in to the scope of lib 2. when a lib implements a new obscure functions, it doesn't automatically get put in to the scope of lib Using the test script (later in this commit) I got the following diff on the API: + diff master fixed-lib 11764a11765,11766 > .types.defaultFunctor > .types.defaultTypeMerge 11774a11777,11778 > .types.isOptionType > .types.isType 11781a11786 > .types.mkOptionType 11788a11794 > .types.setType 11795a11802 > .types.types This means that this commit _adds_ to the API, however I can't find a way to fix these last remaining discrepancies. At least none are _removed_. Test script (run with nix-repl in the PATH): #!/bin/sh set -eux repl() { suff=${1:-} echo "(import ./lib)$suff" \ | nix-repl 2>&1 } attrs_to_check() { repl "${1:-}" \ | tr ';' $'\n' \ | grep "\.\.\." \ | cut -d' ' -f2 \ | sed -e "s/^/${1:-}./" \ | sort } summ() { repl "${1:-}" \ | tr ' ' $'\n' \ | sort \ | uniq } deep_summ() { suff="${1:-}" depth="${2:-4}" depth=$((depth - 1)) summ "$suff" for attr in $(attrs_to_check "$suff" | grep -v "types.types"); do if [ $depth -eq 0 ]; then summ "$attr" | sed -e "s/^/$attr./" else deep_summ "$attr" "$depth" | sed -e "s/^/$attr./" fi done } ( cd nixpkgs #git add . #git commit -m "Auto-commit, sorry" || true git checkout fixed-lib deep_summ > ../fixed-lib git checkout master deep_summ > ../master ) if diff master fixed-lib; then echo "SHALLOW MATCH!" fi ( cd nixpkgs git checkout fixed-lib repl .types )
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{ lib }:
let
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inherit (lib)
all
any
attrByPath
attrNames
catAttrs
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concatLists
concatMap
count
elem
filter
findFirst
flip
foldl
foldl'
getAttrFromPath
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head
id
imap1
isAttrs
isBool
isFunction
isString
length
mapAttrs
mapAttrsToList
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mapAttrsRecursiveCond
min
optional
optionalAttrs
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optionalString
recursiveUpdate
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reverseList sort
setAttrByPath
toList
types
warn
;
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inherit (lib.options)
isOption
mkOption
showDefs
showFiles
showOption
unknownModule
;
in
rec {
/* Evaluate a set of modules. The result is a set of two
attributes: options: the nested set of all option declarations,
and config: the nested set of all option values.
!!! Please think twice before adding to this argument list! The more
that is specified here instead of in the modules themselves the harder
it is to transparently move a set of modules to be a submodule of another
config (as the proper arguments need to be replicated at each call to
evalModules) and the less declarative the module set is. */
evalModules = { modules
, prefix ? []
, # This should only be used for special arguments that need to be evaluated
# when resolving module structure (like in imports). For everything else,
# there's _module.args. If specialArgs.modulesPath is defined it will be
# used as the base path for disabledModules.
specialArgs ? {}
, # This would be remove in the future, Prefer _module.args option instead.
args ? {}
, # This would be remove in the future, Prefer _module.check option instead.
check ? true
}:
let
# This internal module declare internal options under the `_module'
# attribute. These options are fragile, as they are used by the
# module system to change the interpretation of modules.
internalModule = rec {
_file = ./modules.nix;
key = _file;
options = {
_module.args = mkOption {
# Because things like `mkIf` are entirely useless for
# `_module.args` (because there's no way modules can check which
# arguments were passed), we'll use `lazyAttrsOf` which drops
# support for that, in turn it's lazy in its values. This means e.g.
# a `_module.args.pkgs = import (fetchTarball { ... }) {}` won't
# start a download when `pkgs` wasn't evaluated.
type = types.lazyAttrsOf types.unspecified;
internal = true;
description = "Arguments passed to each module.";
};
_module.check = mkOption {
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type = types.bool;
internal = true;
default = check;
description = "Whether to check whether all option definitions have matching declarations.";
};
lib/modules: Implement freeform modules For programs that have a lot of (Nix-representable) configuration options, a simple way to represent this in a NixOS module is to declare an option of a type like `attrsOf str`, representing a key-value mapping which then gets generated into a config file. However with such a type, there's no way to add type checking for only some key values. On the other end of the spectrum, one can declare a single separate option for every key value that the program supports, ending up with a module with potentially 100s of options. This has the benefit that every value gets type checked, catching mistakes at evaluation time already. However the disadvantage is that the module becomes big, becomes coupled to the program version and takes a lot of effort to write and maintain. Previously there was a middle ground between these two extremes: Declare an option of a type like `attrsOf str`, but declare additional separate options for the values you wish to have type checked, and assign their values to the `attrsOf str` option. While this works decently, it has the problem of duplicated options, since now both the additional options and the `attrsOf str` option can be used to set a key value. This leads to confusion about what should happen if both are set, which defaults should apply, and more. Now with this change, a middle ground becomes available that solves above problems: The module system now supports setting a freeform type, which gets used for all definitions that don't have an associated option. This means that you can now declare all options you wish to have type checked, while for the rest a freeform type like `attrsOf str` can be used.
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_module.freeformType = mkOption {
# Disallow merging for now, but could be implemented nicely with a `types.optionType`
type = types.nullOr (types.uniq types.attrs);
internal = true;
lib/modules: Implement freeform modules For programs that have a lot of (Nix-representable) configuration options, a simple way to represent this in a NixOS module is to declare an option of a type like `attrsOf str`, representing a key-value mapping which then gets generated into a config file. However with such a type, there's no way to add type checking for only some key values. On the other end of the spectrum, one can declare a single separate option for every key value that the program supports, ending up with a module with potentially 100s of options. This has the benefit that every value gets type checked, catching mistakes at evaluation time already. However the disadvantage is that the module becomes big, becomes coupled to the program version and takes a lot of effort to write and maintain. Previously there was a middle ground between these two extremes: Declare an option of a type like `attrsOf str`, but declare additional separate options for the values you wish to have type checked, and assign their values to the `attrsOf str` option. While this works decently, it has the problem of duplicated options, since now both the additional options and the `attrsOf str` option can be used to set a key value. This leads to confusion about what should happen if both are set, which defaults should apply, and more. Now with this change, a middle ground becomes available that solves above problems: The module system now supports setting a freeform type, which gets used for all definitions that don't have an associated option. This means that you can now declare all options you wish to have type checked, while for the rest a freeform type like `attrsOf str` can be used.
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default = null;
description = ''
If set, merge all definitions that don't have an associated option
together using this type. The result then gets combined with the
values of all declared options to produce the final <literal>
config</literal> value.
If this is <literal>null</literal>, definitions without an option
will throw an error unless <option>_module.check</option> is
turned off.
'';
};
};
config = {
_module.args = args;
};
};
merged =
let collected = collectModules
(specialArgs.modulesPath or "")
(modules ++ [ internalModule ])
({ inherit lib options config; } // specialArgs);
in mergeModules prefix (reverseList collected);
options = merged.matchedOptions;
lib/modules: Implement freeform modules For programs that have a lot of (Nix-representable) configuration options, a simple way to represent this in a NixOS module is to declare an option of a type like `attrsOf str`, representing a key-value mapping which then gets generated into a config file. However with such a type, there's no way to add type checking for only some key values. On the other end of the spectrum, one can declare a single separate option for every key value that the program supports, ending up with a module with potentially 100s of options. This has the benefit that every value gets type checked, catching mistakes at evaluation time already. However the disadvantage is that the module becomes big, becomes coupled to the program version and takes a lot of effort to write and maintain. Previously there was a middle ground between these two extremes: Declare an option of a type like `attrsOf str`, but declare additional separate options for the values you wish to have type checked, and assign their values to the `attrsOf str` option. While this works decently, it has the problem of duplicated options, since now both the additional options and the `attrsOf str` option can be used to set a key value. This leads to confusion about what should happen if both are set, which defaults should apply, and more. Now with this change, a middle ground becomes available that solves above problems: The module system now supports setting a freeform type, which gets used for all definitions that don't have an associated option. This means that you can now declare all options you wish to have type checked, while for the rest a freeform type like `attrsOf str` can be used.
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config =
let
# For definitions that have an associated option
declaredConfig = mapAttrsRecursiveCond (v: ! isOption v) (_: v: v.value) options;
# If freeformType is set, this is for definitions that don't have an associated option
freeformConfig =
let
defs = map (def: {
file = def.file;
value = setAttrByPath def.prefix def.value;
}) merged.unmatchedDefns;
in if defs == [] then {}
else declaredConfig._module.freeformType.merge prefix defs;
lib/modules: Implement freeform modules For programs that have a lot of (Nix-representable) configuration options, a simple way to represent this in a NixOS module is to declare an option of a type like `attrsOf str`, representing a key-value mapping which then gets generated into a config file. However with such a type, there's no way to add type checking for only some key values. On the other end of the spectrum, one can declare a single separate option for every key value that the program supports, ending up with a module with potentially 100s of options. This has the benefit that every value gets type checked, catching mistakes at evaluation time already. However the disadvantage is that the module becomes big, becomes coupled to the program version and takes a lot of effort to write and maintain. Previously there was a middle ground between these two extremes: Declare an option of a type like `attrsOf str`, but declare additional separate options for the values you wish to have type checked, and assign their values to the `attrsOf str` option. While this works decently, it has the problem of duplicated options, since now both the additional options and the `attrsOf str` option can be used to set a key value. This leads to confusion about what should happen if both are set, which defaults should apply, and more. Now with this change, a middle ground becomes available that solves above problems: The module system now supports setting a freeform type, which gets used for all definitions that don't have an associated option. This means that you can now declare all options you wish to have type checked, while for the rest a freeform type like `attrsOf str` can be used.
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in if declaredConfig._module.freeformType == null then declaredConfig
# Because all definitions that had an associated option ended in
# declaredConfig, freeformConfig can only contain the non-option
# paths, meaning recursiveUpdate will never override any value
else recursiveUpdate freeformConfig declaredConfig;
checkUnmatched =
lib/modules: Implement freeform modules For programs that have a lot of (Nix-representable) configuration options, a simple way to represent this in a NixOS module is to declare an option of a type like `attrsOf str`, representing a key-value mapping which then gets generated into a config file. However with such a type, there's no way to add type checking for only some key values. On the other end of the spectrum, one can declare a single separate option for every key value that the program supports, ending up with a module with potentially 100s of options. This has the benefit that every value gets type checked, catching mistakes at evaluation time already. However the disadvantage is that the module becomes big, becomes coupled to the program version and takes a lot of effort to write and maintain. Previously there was a middle ground between these two extremes: Declare an option of a type like `attrsOf str`, but declare additional separate options for the values you wish to have type checked, and assign their values to the `attrsOf str` option. While this works decently, it has the problem of duplicated options, since now both the additional options and the `attrsOf str` option can be used to set a key value. This leads to confusion about what should happen if both are set, which defaults should apply, and more. Now with this change, a middle ground becomes available that solves above problems: The module system now supports setting a freeform type, which gets used for all definitions that don't have an associated option. This means that you can now declare all options you wish to have type checked, while for the rest a freeform type like `attrsOf str` can be used.
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if config._module.check && config._module.freeformType == null && merged.unmatchedDefns != [] then
lib/modules: improve error-message for undeclared options if prefix contains no options An easy-to-make mistake when declaring e.g. a submodule is the accidental confusion of `options` and `config`: types.submodule { config = { foo = mkOption { /* ... */ }; }; } However the error-message The option `[definition 1-entry 1].foo' defined in `<expr.nix>' does not exist. is fairly unhelpful because it seems as the options are declared at the first sight. In fact, it took a colleague and me a while to track down such a mistake a few days ago and we both agreed that this should be somehow caught to save the time we spent debugging the module in question. At first I decided to catch this error in the `submodules`-type directly by checking whether `options` is undeclared, however this becomes fairly complicated as soon as a submodule-declaration e.g. depends on existing `config`-values which would've lead to some ugly `builtins.tryExec`-heuristic. This patch now simply checks if the option's prefix has any options defined if a point in evaluation is reached where it's clear that the option in question doesn't exist. This means that this patch doesn't change the logic of the module system, it only provides a more detailed error in certain cases: The option `[definition 1-entry 1].foo' defined in `<expr.nix>' does not exist. However it seems as there are no options defined in [definition 1-entry 1]. Are you sure you've declared your options properly? This happens if you e.g. declared your options in `types.submodule' under `config' rather than `options'.
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let
firstDef = head merged.unmatchedDefns;
baseMsg = "The option `${showOption (prefix ++ firstDef.prefix)}' does not exist. Definition values:${showDefs [ firstDef ]}";
lib/modules: improve error-message for undeclared options if prefix contains no options An easy-to-make mistake when declaring e.g. a submodule is the accidental confusion of `options` and `config`: types.submodule { config = { foo = mkOption { /* ... */ }; }; } However the error-message The option `[definition 1-entry 1].foo' defined in `<expr.nix>' does not exist. is fairly unhelpful because it seems as the options are declared at the first sight. In fact, it took a colleague and me a while to track down such a mistake a few days ago and we both agreed that this should be somehow caught to save the time we spent debugging the module in question. At first I decided to catch this error in the `submodules`-type directly by checking whether `options` is undeclared, however this becomes fairly complicated as soon as a submodule-declaration e.g. depends on existing `config`-values which would've lead to some ugly `builtins.tryExec`-heuristic. This patch now simply checks if the option's prefix has any options defined if a point in evaluation is reached where it's clear that the option in question doesn't exist. This means that this patch doesn't change the logic of the module system, it only provides a more detailed error in certain cases: The option `[definition 1-entry 1].foo' defined in `<expr.nix>' does not exist. However it seems as there are no options defined in [definition 1-entry 1]. Are you sure you've declared your options properly? This happens if you e.g. declared your options in `types.submodule' under `config' rather than `options'.
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in
if attrNames options == [ "_module" ]
then throw ''
${baseMsg}
However there are no options defined in `${showOption prefix}'. Are you sure you've
declared your options properly? This can happen if you e.g. declared your options in `types.submodule'
under `config' rather than `options'.
''
else throw baseMsg
else null;
result = builtins.seq checkUnmatched {
inherit options;
config = removeAttrs config [ "_module" ];
inherit (config) _module;
};
in result;
# collectModules :: (modulesPath: String) -> (modules: [ Module ]) -> (args: Attrs) -> [ Module ]
#
# Collects all modules recursively through `import` statements, filtering out
# all modules in disabledModules.
collectModules = let
# Like unifyModuleSyntax, but also imports paths and calls functions if necessary
loadModule = args: fallbackFile: fallbackKey: m:
if isFunction m || isAttrs m then
unifyModuleSyntax fallbackFile fallbackKey (applyIfFunction fallbackKey m args)
else unifyModuleSyntax (toString m) (toString m) (applyIfFunction (toString m) (import m) args);
/*
Collects all modules recursively into the form
{
disabled = [ <list of disabled modules> ];
# All modules of the main module list
modules = [
{
key = <key1>;
module = <module for key1>;
# All modules imported by the module for key1
modules = [
{
key = <key1-1>;
module = <module for key1-1>;
# All modules imported by the module for key1-1
modules = [ ... ];
}
...
];
}
...
];
}
*/
collectStructuredModules =
let
collectResults = modules: {
disabled = concatLists (catAttrs "disabled" modules);
inherit modules;
};
in parentFile: parentKey: initialModules: args: collectResults (imap1 (n: x:
let
module = loadModule args parentFile "${parentKey}:anon-${toString n}" x;
collectedImports = collectStructuredModules module._file module.key module.imports args;
in {
key = module.key;
module = module;
modules = collectedImports.modules;
disabled = module.disabledModules ++ collectedImports.disabled;
}) initialModules);
# filterModules :: String -> { disabled, modules } -> [ Module ]
#
# Filters a structure as emitted by collectStructuredModules by removing all disabled
# modules recursively. It returns the final list of unique-by-key modules
filterModules = modulesPath: { disabled, modules }:
let
moduleKey = m: if isString m then toString modulesPath + "/" + m else toString m;
disabledKeys = map moduleKey disabled;
keyFilter = filter (attrs: ! elem attrs.key disabledKeys);
in map (attrs: attrs.module) (builtins.genericClosure {
startSet = keyFilter modules;
operator = attrs: keyFilter attrs.modules;
});
in modulesPath: initialModules: args:
filterModules modulesPath (collectStructuredModules unknownModule "" initialModules args);
/* Massage a module into canonical form, that is, a set consisting
of options, config and imports attributes. */
unifyModuleSyntax = file: key: m:
let
addMeta = config: if m ? meta
then mkMerge [ config { meta = m.meta; } ]
else config;
addFreeformType = config: if m ? freeformType
then mkMerge [ config { _module.freeformType = m.freeformType; } ]
else config;
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in
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if m ? config || m ? options then
let badAttrs = removeAttrs m ["_file" "key" "disabledModules" "imports" "options" "config" "meta" "freeformType"]; in
if badAttrs != {} then
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: ${toString (attrNames badAttrs)}) into the explicit `config' attribute."
else
{ _file = toString m._file or file;
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key = toString m.key or key;
disabledModules = m.disabledModules or [];
imports = m.imports or [];
options = m.options or {};
config = addFreeformType (addMeta (m.config or {}));
}
else
{ _file = toString m._file or file;
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key = toString m.key or key;
disabledModules = m.disabledModules or [];
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imports = m.require or [] ++ m.imports or [];
options = {};
config = addFreeformType (addMeta (removeAttrs m ["_file" "key" "disabledModules" "require" "imports" "freeformType"]));
};
applyIfFunction = key: f: args@{ config, options, lib, ... }: if isFunction f then
let
# Module arguments are resolved in a strict manner when attribute set
# deconstruction is used. As the arguments are now defined with the
# config._module.args option, the strictness used on the attribute
# set argument would cause an infinite loop, if the result of the
# option is given as argument.
#
# To work-around the strictness issue on the deconstruction of the
# attributes set argument, we create a new attribute set which is
# constructed to satisfy the expected set of attributes. Thus calling
# a module will resolve strictly the attributes used as argument but
# not their values. The values are forwarding the result of the
# evaluation of the option.
requiredArgs = builtins.attrNames (lib.functionArgs f);
context = name: ''while evaluating the module argument `${name}' in "${key}":'';
extraArgs = builtins.listToAttrs (map (name: {
inherit name;
value = builtins.addErrorContext (context name)
(args.${name} or config._module.args.${name});
}) requiredArgs);
# Note: we append in the opposite order such that we can add an error
# context on the explicited arguments of "args" too. This update
# operator is used to make the "args@{ ... }: with args.lib;" notation
# works.
in f (args // extraArgs)
else
f;
/* Merge a list of modules. This will recurse over the option
declarations in all modules, combining them into a single set.
At the same time, for each option declaration, it will merge the
corresponding option definitions in all machines, returning them
in the value attribute of each option.
This returns a set like
{
# A recursive set of options along with their final values
matchedOptions = {
foo = { _type = "option"; value = "option value of foo"; ... };
bar.baz = { _type = "option"; value = "option value of bar.baz"; ... };
...
};
# A list of definitions that weren't matched by any option
unmatchedDefns = [
{ file = "file.nix"; prefix = [ "qux" ]; value = "qux"; }
...
];
}
*/
mergeModules = prefix: modules:
mergeModules' prefix modules
(concatMap (m: map (config: { file = m._file; inherit config; }) (pushDownProperties m.config)) modules);
mergeModules' = prefix: options: configs:
let
/* byName is like foldAttrs, but will look for attributes to merge in the
specified attribute name.
byName "foo" (module: value: ["module.hidden=${module.hidden},value=${value}"])
[
{
hidden="baz";
foo={qux="bar"; gla="flop";};
}
{
hidden="fli";
foo={qux="gne"; gli="flip";};
}
]
===>
{
gla = [ "module.hidden=baz,value=flop" ];
gli = [ "module.hidden=fli,value=flip" ];
qux = [ "module.hidden=baz,value=bar" "module.hidden=fli,value=gne" ];
}
*/
byName = attr: f: modules:
foldl' (acc: module:
acc // (mapAttrs (n: v:
(acc.${n} or []) ++ f module v
) module.${attr}
)
) {} modules;
# an attrset 'name' => list of submodules that declare name.
declsByName = byName "options" (module: option:
[{ inherit (module) _file; options = option; }]
) options;
# an attrset 'name' => list of submodules that define name.
defnsByName = byName "config" (module: value:
map (config: { inherit (module) file; inherit config; }) (pushDownProperties value)
) configs;
# extract the definitions for each loc
defnsByName' = byName "config" (module: value:
[{ inherit (module) file; inherit value; }]
) configs;
resultsByName = flip mapAttrs declsByName (name: decls:
# We're descending into attribute name.
let
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loc = prefix ++ [name];
defns = defnsByName.${name} or [];
defns' = defnsByName'.${name} or [];
nrOptions = count (m: isOption m.options) decls;
in
if nrOptions == length decls then
let opt = fixupOptionType loc (mergeOptionDecls loc decls);
in {
matchedOptions = evalOptionValue loc opt defns';
unmatchedDefns = [];
}
else if nrOptions != 0 then
let
firstOption = findFirst (m: isOption m.options) "" decls;
firstNonOption = findFirst (m: !isOption m.options) "" decls;
in
throw "The option `${showOption loc}' in `${firstOption._file}' is a prefix of options in `${firstNonOption._file}'."
else
mergeModules' loc decls defns);
matchedOptions = mapAttrs (n: v: v.matchedOptions) resultsByName;
# an attrset 'name' => list of unmatched definitions for 'name'
unmatchedDefnsByName =
# Propagate all unmatched definitions from nested option sets
mapAttrs (n: v: v.unmatchedDefns) resultsByName
# Plus the definitions for the current prefix that don't have a matching option
// removeAttrs defnsByName' (attrNames matchedOptions);
in {
inherit matchedOptions;
# Transforms unmatchedDefnsByName into a list of definitions
unmatchedDefns = concatLists (mapAttrsToList (name: defs:
map (def: def // {
# Set this so we know when the definition first left unmatched territory
prefix = [name] ++ (def.prefix or []);
}) defs
) unmatchedDefnsByName);
};
/* Merge multiple option declarations into a single declaration. In
general, there should be only one declaration of each option.
The exception is the options attribute, which specifies
sub-options. These can be specified multiple times to allow one
module to add sub-options to an option declared somewhere else
(e.g. multiple modules define sub-options for fileSystems).
'loc' is the list of attribute names where the option is located.
'opts' is a list of modules. Each module has an options attribute which
correspond to the definition of 'loc' in 'opt.file'. */
mergeOptionDecls =
let
packSubmodule = file: m:
{ _file = file; imports = [ m ]; };
coerceOption = file: opt:
if isFunction opt then packSubmodule file opt
else packSubmodule file { options = opt; };
in loc: opts:
foldl' (res: opt:
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let t = res.type;
t' = opt.options.type;
mergedType = t.typeMerge t'.functor;
typesMergeable = mergedType != null;
typeSet = if (bothHave "type") && typesMergeable
then { type = mergedType; }
else {};
bothHave = k: opt.options ? ${k} && res ? ${k};
in
if bothHave "default" ||
bothHave "example" ||
bothHave "description" ||
bothHave "apply" ||
(bothHave "type" && (! typesMergeable))
then
throw "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
else
let
/* Add the modules of the current option to the list of modules
already collected. The options attribute except either a list of
submodules or a submodule. For each submodule, we add the file of the
current option declaration as the file use for the submodule. If the
submodule defines any filename, then we ignore the enclosing option file. */
options' = toList opt.options.options;
getSubModules = opt.options.type.getSubModules or null;
submodules =
if getSubModules != null then map (packSubmodule opt._file) getSubModules ++ res.options
else if opt.options ? options then map (coerceOption opt._file) options' ++ res.options
else res.options;
in opt.options // res //
{ declarations = res.declarations ++ [opt._file];
options = submodules;
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} // typeSet
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) { inherit loc; declarations = []; options = []; } opts;
/* Merge all the definitions of an option to produce the final
config value. */
evalOptionValue = loc: opt: defs:
let
# Add in the default value for this option, if any.
defs' =
(optional (opt ? default)
{ file = head opt.declarations; value = mkOptionDefault opt.default; }) ++ defs;
# Handle properties, check types, and merge everything together.
res =
if opt.readOnly or false && length defs' > 1 then
let
# For a better error message, evaluate all readOnly definitions as
# if they were the only definition.
separateDefs = map (def: def // {
value = (mergeDefinitions loc opt.type [ def ]).mergedValue;
}) defs';
in throw "The option `${showOption loc}' is read-only, but it's set multiple times. Definition values:${showDefs separateDefs}"
else
mergeDefinitions loc opt.type defs';
# Apply the 'apply' function to the merged value. This allows options to
# yield a value computed from the definitions
value = if opt ? apply then opt.apply res.mergedValue else res.mergedValue;
warnDeprecation =
if opt.type.deprecationMessage == null then id
else warn "The type `types.${opt.type.name}' of option `${showOption loc}' defined in ${showFiles opt.declarations} is deprecated. ${opt.type.deprecationMessage}";
in warnDeprecation opt //
{ value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
inherit (res.defsFinal') highestPrio;
definitions = map (def: def.value) res.defsFinal;
files = map (def: def.file) res.defsFinal;
inherit (res) isDefined;
};
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# Merge definitions of a value of a given type.
mergeDefinitions = loc: type: defs: rec {
defsFinal' =
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let
# Process mkMerge and mkIf properties.
defs' = concatMap (m:
map (value: { inherit (m) file; inherit value; }) (builtins.addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))
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) defs;
# Process mkOverride properties.
defs'' = filterOverrides' defs';
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# Sort mkOrder properties.
defs''' =
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# Avoid sorting if we don't have to.
if any (def: def.value._type or "" == "order") defs''.values
then sortProperties defs''.values
else defs''.values;
in {
values = defs''';
inherit (defs'') highestPrio;
};
defsFinal = defsFinal'.values;
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# Type-check the remaining definitions, and merge them. Or throw if no definitions.
mergedValue =
if isDefined then
if all (def: type.check def.value) defsFinal then type.merge loc defsFinal
else let allInvalid = filter (def: ! type.check def.value) defsFinal;
in throw "A definition for option `${showOption loc}' is not of type `${type.description}'. Definition values:${showDefs allInvalid}"
else
# (nixos-option detects this specific error message and gives it special
# handling. If changed here, please change it there too.)
throw "The option `${showOption loc}' is used but not defined.";
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isDefined = defsFinal != [];
optionalValue =
if isDefined then { value = mergedValue; }
else {};
};
/* Given a config set, expand mkMerge properties, and push down the
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other properties into the children. The result is a list of
config sets that do not have properties at top-level. For
example,
mkMerge [ { boot = set1; } (mkIf cond { boot = set2; services = set3; }) ]
is transformed into
[ { boot = set1; } { boot = mkIf cond set2; services = mkIf cond set3; } ].
This transform is the critical step that allows mkIf conditions
to refer to the full configuration without creating an infinite
recursion.
*/
pushDownProperties = cfg:
if cfg._type or "" == "merge" then
concatMap pushDownProperties cfg.contents
else if cfg._type or "" == "if" then
map (mapAttrs (n: v: mkIf cfg.condition v)) (pushDownProperties cfg.content)
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else if cfg._type or "" == "override" then
map (mapAttrs (n: v: mkOverride cfg.priority v)) (pushDownProperties cfg.content)
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else # FIXME: handle mkOrder?
[ cfg ];
/* Given a config value, expand mkMerge properties, and discharge
any mkIf conditions. That is, this is the place where mkIf
conditions are actually evaluated. The result is a list of
config values. For example, mkIf false x yields [],
mkIf true x yields [x], and
mkMerge [ 1 (mkIf true 2) (mkIf true (mkIf false 3)) ]
yields [ 1 2 ].
*/
dischargeProperties = def:
if def._type or "" == "merge" then
concatMap dischargeProperties def.contents
else if def._type or "" == "if" then
if isBool def.condition then
if def.condition then
dischargeProperties def.content
else
[ ]
else
throw "mkIf called with a non-Boolean condition"
else
[ def ];
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/* Given a list of config values, process the mkOverride properties,
that is, return the values that have the highest (that is,
numerically lowest) priority, and strip the mkOverride
properties. For example,
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[ { file = "/1"; value = mkOverride 10 "a"; }
{ file = "/2"; value = mkOverride 20 "b"; }
{ file = "/3"; value = "z"; }
{ file = "/4"; value = mkOverride 10 "d"; }
]
yields
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[ { file = "/1"; value = "a"; }
{ file = "/4"; value = "d"; }
]
Note that "z" has the default priority 100.
*/
filterOverrides = defs: (filterOverrides' defs).values;
filterOverrides' = defs:
let
getPrio = def: if def.value._type or "" == "override" then def.value.priority else defaultPriority;
highestPrio = foldl' (prio: def: min (getPrio def) prio) 9999 defs;
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strip = def: if def.value._type or "" == "override" then def // { value = def.value.content; } else def;
in {
values = concatMap (def: if getPrio def == highestPrio then [(strip def)] else []) defs;
inherit highestPrio;
};
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/* Sort a list of properties. The sort priority of a property is
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1000 by default, but can be overridden by wrapping the property
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using mkOrder. */
sortProperties = defs:
let
strip = def:
if def.value._type or "" == "order"
then def // { value = def.value.content; inherit (def.value) priority; }
else def;
defs' = map strip defs;
compare = a: b: (a.priority or 1000) < (b.priority or 1000);
in sort compare defs';
/* Hack for backward compatibility: convert options of type
optionSet to options of type submodule. FIXME: remove
eventually. */
fixupOptionType = loc: opt:
let
options = opt.options or
(throw "Option `${showOption loc}' has type optionSet but has no option attribute, in ${showFiles opt.declarations}.");
f = tp:
let optionSetIn = type: (tp.name == type) && (tp.functor.wrapped.name == "optionSet");
in
if tp.name == "option set" || tp.name == "submodule" then
throw "The option ${showOption loc} uses submodules without a wrapping type, in ${showFiles opt.declarations}."
else if optionSetIn "attrsOf" then types.attrsOf (types.submodule options)
else if optionSetIn "listOf" then types.listOf (types.submodule options)
else if optionSetIn "nullOr" then types.nullOr (types.submodule options)
else tp;
in
if opt.type.getSubModules or null == null
then opt // { type = f (opt.type or types.unspecified); }
else opt // { type = opt.type.substSubModules opt.options; options = []; };
/* Properties. */
mkIf = condition: content:
{ _type = "if";
inherit condition content;
};
mkAssert = assertion: message: content:
mkIf
(if assertion then true else throw "\nFailed assertion: ${message}")
content;
mkMerge = contents:
{ _type = "merge";
inherit contents;
};
mkOverride = priority: content:
{ _type = "override";
inherit priority content;
};
mkOptionDefault = mkOverride 1500; # priority of option defaults
mkDefault = mkOverride 1000; # used in config sections of non-user modules to set a default
mkForce = mkOverride 50;
mkVMOverride = mkOverride 10; # used by nixos-rebuild build-vm
mkStrict = builtins.trace "`mkStrict' is obsolete; use `mkOverride 0' instead." (mkOverride 0);
mkFixStrictness = id; # obsolete, no-op
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mkOrder = priority: content:
{ _type = "order";
inherit priority content;
};
mkBefore = mkOrder 500;
mkAfter = mkOrder 1500;
# The default priority for things that don't have a priority specified.
defaultPriority = 100;
# Convenient property used to transfer all definitions and their
# properties from one option to another. This property is useful for
# renaming options, and also for including properties from another module
# system, including sub-modules.
#
# { config, options, ... }:
#
# {
# # 'bar' might not always be defined in the current module-set.
# config.foo.enable = mkAliasDefinitions (options.bar.enable or {});
#
# # 'barbaz' has to be defined in the current module-set.
# config.foobar.paths = mkAliasDefinitions options.barbaz.paths;
# }
#
# Note, this is different than taking the value of the option and using it
# as a definition, as the new definition will not keep the mkOverride /
# mkDefault properties of the previous option.
#
mkAliasDefinitions = mkAliasAndWrapDefinitions id;
mkAliasAndWrapDefinitions = wrap: option:
mkAliasIfDef option (wrap (mkMerge option.definitions));
# Similar to mkAliasAndWrapDefinitions but copies over the priority from the
# option as well.
#
# If a priority is not set, it assumes a priority of defaultPriority.
mkAliasAndWrapDefsWithPriority = wrap: option:
let
prio = option.highestPrio or defaultPriority;
defsWithPrio = map (mkOverride prio) option.definitions;
in mkAliasIfDef option (wrap (mkMerge defsWithPrio));
mkAliasIfDef = option:
mkIf (isOption option && option.isDefined);
/* Compatibility. */
fixMergeModules = modules: args: evalModules { inherit modules args; check = false; };
/* Return a module that causes a warning to be shown if the
specified option is defined. For example,
mkRemovedOptionModule [ "boot" "loader" "grub" "bootDevice" ] "<replacement instructions>"
causes a assertion if the user defines boot.loader.grub.bootDevice.
replacementInstructions is a string that provides instructions on
how to achieve the same functionality without the removed option,
or alternatively a reasoning why the functionality is not needed.
replacementInstructions SHOULD be provided!
*/
mkRemovedOptionModule = optionName: replacementInstructions:
{ options, ... }:
{ options = setAttrByPath optionName (mkOption {
visible = false;
apply = x: throw "The option `${showOption optionName}' can no longer be used since it's been removed. ${replacementInstructions}";
});
config.assertions =
let opt = getAttrFromPath optionName options; in [{
assertion = !opt.isDefined;
message = ''
The option definition `${showOption optionName}' in ${showFiles opt.files} no longer has any effect; please remove it.
${replacementInstructions}
'';
}];
};
/* Return a module that causes a warning to be shown if the
specified "from" option is defined; the defined value is however
forwarded to the "to" option. This can be used to rename options
while providing backward compatibility. For example,
mkRenamedOptionModule [ "boot" "copyKernels" ] [ "boot" "loader" "grub" "copyKernels" ]
forwards any definitions of boot.copyKernels to
boot.loader.grub.copyKernels while printing a warning.
This also copies over the priority from the aliased option to the
non-aliased option.
*/
mkRenamedOptionModule = from: to: doRename {
inherit from to;
visible = false;
warn = true;
use = builtins.trace "Obsolete option `${showOption from}' is used. It was renamed to `${showOption to}'.";
};
/* Return a module that causes a warning to be shown if any of the "from"
option is defined; the defined values can be used in the "mergeFn" to set
the "to" value.
This function can be used to merge multiple options into one that has a
different type.
"mergeFn" takes the module "config" as a parameter and must return a value
of "to" option type.
mkMergedOptionModule
[ [ "a" "b" "c" ]
[ "d" "e" "f" ] ]
[ "x" "y" "z" ]
(config:
let value = p: getAttrFromPath p config;
in
if (value [ "a" "b" "c" ]) == true then "foo"
else if (value [ "d" "e" "f" ]) == true then "bar"
else "baz")
- options.a.b.c is a removed boolean option
- options.d.e.f is a removed boolean option
- options.x.y.z is a new str option that combines a.b.c and d.e.f
functionality
This show a warning if any a.b.c or d.e.f is set, and set the value of
x.y.z to the result of the merge function
*/
mkMergedOptionModule = from: to: mergeFn:
{ config, options, ... }:
{
options = foldl recursiveUpdate {} (map (path: setAttrByPath path (mkOption {
visible = false;
# To use the value in mergeFn without triggering errors
default = "_mkMergedOptionModule";
})) from);
config = {
warnings = filter (x: x != "") (map (f:
let val = getAttrFromPath f config;
opt = getAttrFromPath f options;
in
optionalString
(val != "_mkMergedOptionModule")
"The option `${showOption f}' defined in ${showFiles opt.files} has been changed to `${showOption to}' that has a different type. Please read `${showOption to}' documentation and update your configuration accordingly."
) from);
} // setAttrByPath to (mkMerge
(optional
(any (f: (getAttrFromPath f config) != "_mkMergedOptionModule") from)
(mergeFn config)));
};
/* Single "from" version of mkMergedOptionModule.
Return a module that causes a warning to be shown if the "from" option is
defined; the defined value can be used in the "mergeFn" to set the "to"
value.
This function can be used to change an option into another that has a
different type.
"mergeFn" takes the module "config" as a parameter and must return a value of
"to" option type.
mkChangedOptionModule [ "a" "b" "c" ] [ "x" "y" "z" ]
(config:
let value = getAttrFromPath [ "a" "b" "c" ] config;
in
if value > 100 then "high"
else "normal")
- options.a.b.c is a removed int option
- options.x.y.z is a new str option that supersedes a.b.c
This show a warning if a.b.c is set, and set the value of x.y.z to the
result of the change function
*/
mkChangedOptionModule = from: to: changeFn:
mkMergedOptionModule [ from ] to changeFn;
/* Like mkRenamedOptionModule, but doesn't show a warning. */
mkAliasOptionModule = from: to: doRename {
inherit from to;
visible = true;
warn = false;
use = id;
};
doRename = { from, to, visible, warn, use, withPriority ? true }:
{ config, options, ... }:
let
fromOpt = getAttrFromPath from options;
toOf = attrByPath to
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(abort "Renaming error: option `${showOption to}' does not exist.");
toType = let opt = attrByPath to {} options; in opt.type or (types.submodule {});
in
{
options = setAttrByPath from (mkOption {
inherit visible;
description = "Alias of <option>${showOption to}</option>.";
apply = x: use (toOf config);
} // optionalAttrs (toType != null) {
type = toType;
});
config = mkMerge [
{
warnings = optional (warn && fromOpt.isDefined)
"The option `${showOption from}' defined in ${showFiles fromOpt.files} has been renamed to `${showOption to}'.";
}
(if withPriority
then mkAliasAndWrapDefsWithPriority (setAttrByPath to) fromOpt
else mkAliasAndWrapDefinitions (setAttrByPath to) fromOpt)
];
};
/* Use this function to import a JSON file as NixOS configuration.
importJSON -> path -> attrs
*/
importJSON = file: {
_file = file;
config = lib.importJSON file;
};
/* Use this function to import a TOML file as NixOS configuration.
importTOML -> path -> attrs
*/
importTOML = file: {
_file = file;
config = lib.importTOML file;
};
}