/*
Manages /etc/nix/nix.conf.
See also
- ./nix-channel.nix
- ./nix-flakes.nix
- ./nix-remote-build.nix
- nixos/modules/services/system/nix-daemon.nix
*/
{
config,
lib,
pkgs,
...
}:
let
inherit (lib)
concatStringsSep
boolToString
escape
filterAttrs
floatToString
getVersion
hasPrefix
isBool
isDerivation
isFloat
isInt
isList
isString
literalExpression
mapAttrsToList
mkAfter
mkIf
mkOption
mkRenamedOptionModuleWith
optionalString
optionals
strings
systems
toPretty
types
versionAtLeast
;
cfg = config.nix;
nixPackage = cfg.package.out;
isNixAtLeast = versionAtLeast (getVersion nixPackage);
defaultSystemFeatures =
[
"nixos-test"
"benchmark"
"big-parallel"
"kvm"
]
++ optionals (pkgs.stdenv.hostPlatform ? gcc.arch) (
# a builder can run code for `gcc.arch` and inferior architectures
[ "gccarch-${pkgs.stdenv.hostPlatform.gcc.arch}" ]
++ map (x: "gccarch-${x}") (
systems.architectures.inferiors.${pkgs.stdenv.hostPlatform.gcc.arch} or [ ]
)
);
legacyConfMappings = {
useSandbox = "sandbox";
buildCores = "cores";
maxJobs = "max-jobs";
sandboxPaths = "extra-sandbox-paths";
binaryCaches = "substituters";
trustedBinaryCaches = "trusted-substituters";
binaryCachePublicKeys = "trusted-public-keys";
autoOptimiseStore = "auto-optimise-store";
requireSignedBinaryCaches = "require-sigs";
trustedUsers = "trusted-users";
allowedUsers = "allowed-users";
systemFeatures = "system-features";
};
semanticConfType =
with types;
let
confAtom =
nullOr (oneOf [
bool
int
float
str
path
package
])
// {
description = "Nix config atom (null, bool, int, float, str, path or package)";
};
in
attrsOf (either confAtom (listOf confAtom));
nixConf =
assert isNixAtLeast "2.2";
let
mkValueString =
v:
if v == null then
""
else if isInt v then
toString v
else if isBool v then
boolToString v
else if isFloat v then
floatToString v
else if isList v then
toString v
else if isDerivation v then
toString v
else if builtins.isPath v then
toString v
else if isString v then
v
else if strings.isConvertibleWithToString v then
toString v
else
abort "The nix conf value: ${toPretty { } v} can not be encoded";
mkKeyValue = k: v: "${escape [ "=" ] k} = ${mkValueString v}";
mkKeyValuePairs = attrs: concatStringsSep "\n" (mapAttrsToList mkKeyValue attrs);
isExtra = key: hasPrefix "extra-" key;
in
pkgs.writeTextFile {
name = "nix.conf";
# workaround for https://github.com/NixOS/nix/issues/9487
# extra-* settings must come after their non-extra counterpart
text = ''
# WARNING: this file is generated from the nix.* options in
# your NixOS configuration, typically
# /etc/nixos/configuration.nix. Do not edit it!
${mkKeyValuePairs (filterAttrs (key: value: !(isExtra key)) cfg.settings)}
${mkKeyValuePairs (filterAttrs (key: value: isExtra key) cfg.settings)}
${cfg.extraOptions}
'';
checkPhase = lib.optionalString cfg.checkConfig (
if pkgs.stdenv.hostPlatform != pkgs.stdenv.buildPlatform then
''
echo "Ignoring validation for cross-compilation"
''
else
let
showCommand = if isNixAtLeast "2.20pre" then "config show" else "show-config";
in
''
echo "Validating generated nix.conf"
ln -s $out ./nix.conf
set -e
set +o pipefail
NIX_CONF_DIR=$PWD \
${cfg.package}/bin/nix ${showCommand} ${optionalString (isNixAtLeast "2.3pre") "--no-net"} \
${optionalString (isNixAtLeast "2.4pre") "--option experimental-features nix-command"} \
|& sed -e 's/^warning:/error:/' \
| (! grep '${if cfg.checkAllErrors then "^error:" else "^error: unknown setting"}')
set -o pipefail
''
);
};
in
{
imports =
[
(mkRenamedOptionModuleWith {
sinceRelease = 2003;
from = [
"nix"
"useChroot"
];
to = [
"nix"
"useSandbox"
];
})
(mkRenamedOptionModuleWith {
sinceRelease = 2003;
from = [
"nix"
"chrootDirs"
];
to = [
"nix"
"sandboxPaths"
];
})
]
++ mapAttrsToList (
oldConf: newConf:
mkRenamedOptionModuleWith {
sinceRelease = 2205;
from = [
"nix"
oldConf
];
to = [
"nix"
"settings"
newConf
];
}
) legacyConfMappings;
options = {
nix = {
checkConfig = mkOption {
type = types.bool;
default = true;
description = ''
If enabled, checks that Nix can parse the generated nix.conf.
'';
};
checkAllErrors = mkOption {
type = types.bool;
default = true;
description = ''
If enabled, checks the nix.conf parsing for any kind of error. When disabled, checks only for unknown settings.
'';
};
extraOptions = mkOption {
type = types.lines;
default = "";
example = ''
keep-outputs = true
keep-derivations = true
'';
description = "Additional text appended to {file}`nix.conf`.";
};
settings = mkOption {
type = types.submodule {
freeformType = semanticConfType;
options = {
max-jobs = mkOption {
type = types.either types.int (types.enum [ "auto" ]);
default = "auto";
example = 64;
description = ''
This option defines the maximum number of jobs that Nix will try to
build in parallel. The default is auto, which means it will use all
available logical cores. It is recommend to set it to the total
number of logical cores in your system (e.g., 16 for two CPUs with 4
cores each and hyper-threading).
'';
};
auto-optimise-store = mkOption {
type = types.bool;
default = false;
example = true;
description = ''
If set to true, Nix automatically detects files in the store that have
identical contents, and replaces them with hard links to a single copy.
This saves disk space. If set to false (the default), you can still run
nix-store --optimise to get rid of duplicate files.
'';
};
cores = mkOption {
type = types.int;
default = 0;
example = 64;
description = ''
This option defines the maximum number of concurrent tasks during
one build. It affects, e.g., -j option for make.
The special value 0 means that the builder should use all
available CPU cores in the system. Some builds may become
non-deterministic with this option; use with care! Packages will
only be affected if enableParallelBuilding is set for them.
'';
};
sandbox = mkOption {
type = types.either types.bool (types.enum [ "relaxed" ]);
default = true;
description = ''
If set, Nix will perform builds in a sandboxed environment that it
will set up automatically for each build. This prevents impurities
in builds by disallowing access to dependencies outside of the Nix
store by using network and mount namespaces in a chroot environment.
This is enabled by default even though it has a possible performance
impact due to the initial setup time of a sandbox for each build. It
doesn't affect derivation hashes, so changing this option will not
trigger a rebuild of packages.
When set to "relaxed", this option permits derivations that set
`__noChroot = true;` to run outside of the sandboxed environment.
Exercise caution when using this mode of operation! It is intended to
be a quick hack when building with packages that are not easily setup
to be built reproducibly.
'';
};
extra-sandbox-paths = mkOption {
type = types.listOf types.str;
default = [ ];
example = [
"/dev"
"/proc"
];
description = ''
Directories from the host filesystem to be included
in the sandbox.
'';
};
substituters = mkOption {
type = types.listOf types.str;
description = ''
List of binary cache URLs used to obtain pre-built binaries
of Nix packages.
By default https://cache.nixos.org/ is added.
'';
};
trusted-substituters = mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "https://hydra.nixos.org/" ];
description = ''
List of binary cache URLs that non-root users can use (in
addition to those specified using
{option}`nix.settings.substituters`) by passing
`--option binary-caches` to Nix commands.
'';
};
require-sigs = mkOption {
type = types.bool;
default = true;
description = ''
If enabled (the default), Nix will only download binaries from binary caches if
they are cryptographically signed with any of the keys listed in
{option}`nix.settings.trusted-public-keys`. If disabled, signatures are neither
required nor checked, so it's strongly recommended that you use only
trustworthy caches and https to prevent man-in-the-middle attacks.
'';
};
trusted-public-keys = mkOption {
type = types.listOf types.str;
example = [ "hydra.nixos.org-1:CNHJZBh9K4tP3EKF6FkkgeVYsS3ohTl+oS0Qa8bezVs=" ];
description = ''
List of public keys used to sign binary caches. If
{option}`nix.settings.trusted-public-keys` is enabled,
then Nix will use a binary from a binary cache if and only
if it is signed by *any* of the keys
listed here. By default, only the key for
`cache.nixos.org` is included.
'';
};
trusted-users = mkOption {
type = types.listOf types.str;
example = [
"root"
"alice"
"@wheel"
];
description = ''
A list of names of users that have additional rights when
connecting to the Nix daemon, such as the ability to specify
additional binary caches, or to import unsigned NARs. You
can also specify groups by prefixing them with
`@`; for instance,
`@wheel` means all users in the wheel
group.
'';
};
system-features = mkOption {
type = types.listOf types.str;
# We expose system-featuers here and in config below.
# This allows users to access the default value via `options.nix.settings.system-features`
default = defaultSystemFeatures;
defaultText = literalExpression ''[ "nixos-test" "benchmark" "big-parallel" "kvm" "gccarch-<arch>" ]'';
description = ''
The set of features supported by the machine. Derivations
can express dependencies on system features through the
`requiredSystemFeatures` attribute.
'';
};
allowed-users = mkOption {
type = types.listOf types.str;
default = [ "*" ];
example = [
"@wheel"
"@builders"
"alice"
"bob"
];
description = ''
A list of names of users (separated by whitespace) that are
allowed to connect to the Nix daemon. As with
{option}`nix.settings.trusted-users`, you can specify groups by
prefixing them with `@`. Also, you can
allow all users by specifying `*`. The
default is `*`. Note that trusted users are
always allowed to connect.
'';
};
};
};
default = { };
example = literalExpression ''
{
use-sandbox = true;
show-trace = true;
sandbox-paths = [ "/bin/sh=''${pkgs.busybox-sandbox-shell.out}/bin/busybox" ];
}
'';
description = ''
Configuration for Nix, see
<https://nixos.org/manual/nix/stable/command-ref/conf-file.html> or
{manpage}`nix.conf(5)` for available options.
The value declared here will be translated directly to the key-value pairs Nix expects.
You can use {command}`nix-instantiate --eval --strict '<nixpkgs/nixos>' -A config.nix.settings`
to view the current value. By default it is empty.
Nix configurations defined under {option}`nix.*` will be translated and applied to this
option. In addition, configuration specified in {option}`nix.extraOptions` will be appended
verbatim to the resulting config file.
'';
};
};
};
config = mkIf cfg.enable {
environment.etc."nix/nix.conf".source = nixConf;
nix.settings = {
trusted-public-keys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
trusted-users = [ "root" ];
substituters = mkAfter [ "https://cache.nixos.org/" ];
system-features = defaultSystemFeatures;
};
};
}