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Merge pull request #241690 from hercules-ci/nixos-nix-modules

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Split nixos/nix-daemon.nix
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Robert Hensing 2023-07-07 10:29:58 +02:00 committed by GitHub
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70
nixos/modules/config/nix-channel.nix Normal file
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/*
Manages the things that are needed for a traditional nix-channel based
configuration to work.
See also
- ./nix.nix
- ./nix-flakes.nix
*/
{ config, lib, ... }:
let
inherit (lib)
mkIf
mkOption
stringAfter
types
;
cfg = config.nix;
in
{
options = {
nix = {
nixPath = mkOption {
type = types.listOf types.str;
default = [
"nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
"nixos-config=/etc/nixos/configuration.nix"
"/nix/var/nix/profiles/per-user/root/channels"
];
description = lib.mdDoc ''
The default Nix expression search path, used by the Nix
evaluator to look up paths enclosed in angle brackets
(e.g. `<nixpkgs>`).
'';
};
};
system = {
defaultChannel = mkOption {
internal = true;
type = types.str;
default = "https://nixos.org/channels/nixos-unstable";
description = lib.mdDoc "Default NixOS channel to which the root user is subscribed.";
};
};
};
config = mkIf cfg.enable {
environment.extraInit =
''
if [ -e "$HOME/.nix-defexpr/channels" ]; then
export NIX_PATH="$HOME/.nix-defexpr/channels''${NIX_PATH:+:$NIX_PATH}"
fi
'';
environment.sessionVariables = {
NIX_PATH = cfg.nixPath;
};
system.activationScripts.nix-channel = stringAfter [ "etc" "users" ]
''
# Subscribe the root user to the NixOS channel by default.
if [ ! -e "/root/.nix-channels" ]; then
echo "${config.system.defaultChannel} nixos" > "/root/.nix-channels"
fi
'';
};
}

95
nixos/modules/config/nix-flakes.nix Normal file
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/*
Manages the flake registry.
See also
- ./nix.nix
- ./nix-channel.nix
*/
{ config, lib, ... }:
let
inherit (lib)
filterAttrs
literalExpression
mapAttrsToList
mkDefault
mkIf
mkOption
types
;
cfg = config.nix;
in
{
options = {
nix = {
registry = mkOption {
type = types.attrsOf (types.submodule (
let
referenceAttrs = with types; attrsOf (oneOf [
str
int
bool
path
package
]);
in
{ config, name, ... }:
{
options = {
from = mkOption {
type = referenceAttrs;
example = { type = "indirect"; id = "nixpkgs"; };
description = lib.mdDoc "The flake reference to be rewritten.";
};
to = mkOption {
type = referenceAttrs;
example = { type = "github"; owner = "my-org"; repo = "my-nixpkgs"; };
description = lib.mdDoc "The flake reference {option}`from` is rewritten to.";
};
flake = mkOption {
type = types.nullOr types.attrs;
default = null;
example = literalExpression "nixpkgs";
description = lib.mdDoc ''
The flake input {option}`from` is rewritten to.
'';
};
exact = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Whether the {option}`from` reference needs to match exactly. If set,
a {option}`from` reference like `nixpkgs` does not
match with a reference like `nixpkgs/nixos-20.03`.
'';
};
};
config = {
from = mkDefault { type = "indirect"; id = name; };
to = mkIf (config.flake != null) (mkDefault (
{
type = "path";
path = config.flake.outPath;
} // filterAttrs
(n: _: n == "lastModified" || n == "rev" || n == "revCount" || n == "narHash")
config.flake
));
};
}
));
default = { };
description = lib.mdDoc ''
A system-wide flake registry.
'';
};
};
};
config = mkIf cfg.enable {
environment.etc."nix/registry.json".text = builtins.toJSON {
version = 2;
flakes = mapAttrsToList (n: v: { inherit (v) from to exact; }) cfg.registry;
};
};
}

230
nixos/modules/config/nix-remote-build.nix Normal file
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/*
Manages the remote build configuration, /etc/nix/machines
See also
- ./nix.nix
- nixos/modules/services/system/nix-daemon.nix
*/
{ config, lib, ... }:
let
inherit (lib)
any
concatMapStrings
concatStringsSep
filter
getVersion
mkIf
mkMerge
mkOption
optional
optionalString
types
versionAtLeast
;
cfg = config.nix;
nixPackage = cfg.package.out;
isNixAtLeast = versionAtLeast (getVersion nixPackage);
buildMachinesText =
concatMapStrings
(machine:
(concatStringsSep " " ([
"${optionalString (machine.protocol != null) "${machine.protocol}://"}${optionalString (machine.sshUser != null) "${machine.sshUser}@"}${machine.hostName}"
(if machine.system != null then machine.system else if machine.systems != [ ] then concatStringsSep "," machine.systems else "-")
(if machine.sshKey != null then machine.sshKey else "-")
(toString machine.maxJobs)
(toString machine.speedFactor)
(let res = (machine.supportedFeatures ++ machine.mandatoryFeatures);
in if (res == []) then "-" else (concatStringsSep "," res))
(let res = machine.mandatoryFeatures;
in if (res == []) then "-" else (concatStringsSep "," machine.mandatoryFeatures))
]
++ optional (isNixAtLeast "2.4pre") (if machine.publicHostKey != null then machine.publicHostKey else "-")))
+ "\n"
)
cfg.buildMachines;
in
{
imports = [
./nix.nix
];
options = {
nix = {
buildMachines = mkOption {
type = types.listOf (types.submodule {
options = {
hostName = mkOption {
type = types.str;
example = "nixbuilder.example.org";
description = lib.mdDoc ''
The hostname of the build machine.
'';
};
protocol = mkOption {
type = types.enum [ null "ssh" "ssh-ng" ];
default = "ssh";
example = "ssh-ng";
description = lib.mdDoc ''
The protocol used for communicating with the build machine.
Use `ssh-ng` if your remote builder and your
local Nix version support that improved protocol.
Use `null` when trying to change the special localhost builder
without a protocol which is for example used by hydra.
'';
};
system = mkOption {
type = types.nullOr types.str;
default = null;
example = "x86_64-linux";
description = lib.mdDoc ''
The system type the build machine can execute derivations on.
Either this attribute or {var}`systems` must be
present, where {var}`system` takes precedence if
both are set.
'';
};
systems = mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "x86_64-linux" "aarch64-linux" ];
description = lib.mdDoc ''
The system types the build machine can execute derivations on.
Either this attribute or {var}`system` must be
present, where {var}`system` takes precedence if
both are set.
'';
};
sshUser = mkOption {
type = types.nullOr types.str;
default = null;
example = "builder";
description = lib.mdDoc ''
The username to log in as on the remote host. This user must be
able to log in and run nix commands non-interactively. It must
also be privileged to build derivations, so must be included in
{option}`nix.settings.trusted-users`.
'';
};
sshKey = mkOption {
type = types.nullOr types.str;
default = null;
example = "/root/.ssh/id_buildhost_builduser";
description = lib.mdDoc ''
The path to the SSH private key with which to authenticate on
the build machine. The private key must not have a passphrase.
If null, the building user (root on NixOS machines) must have an
appropriate ssh configuration to log in non-interactively.
Note that for security reasons, this path must point to a file
in the local filesystem, *not* to the nix store.
'';
};
maxJobs = mkOption {
type = types.int;
default = 1;
description = lib.mdDoc ''
The number of concurrent jobs the build machine supports. The
build machine will enforce its own limits, but this allows hydra
to schedule better since there is no work-stealing between build
machines.
'';
};
speedFactor = mkOption {
type = types.int;
default = 1;
description = lib.mdDoc ''
The relative speed of this builder. This is an arbitrary integer
that indicates the speed of this builder, relative to other
builders. Higher is faster.
'';
};
mandatoryFeatures = mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "big-parallel" ];
description = lib.mdDoc ''
A list of features mandatory for this builder. The builder will
be ignored for derivations that don't require all features in
this list. All mandatory features are automatically included in
{var}`supportedFeatures`.
'';
};
supportedFeatures = mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "kvm" "big-parallel" ];
description = lib.mdDoc ''
A list of features supported by this builder. The builder will
be ignored for derivations that require features not in this
list.
'';
};
publicHostKey = mkOption {
type = types.nullOr types.str;
default = null;
description = lib.mdDoc ''
The (base64-encoded) public host key of this builder. The field
is calculated via {command}`base64 -w0 /etc/ssh/ssh_host_type_key.pub`.
If null, SSH will use its regular known-hosts file when connecting.
'';
};
};
});
default = [ ];
description = lib.mdDoc ''
This option lists the machines to be used if distributed builds are
enabled (see {option}`nix.distributedBuilds`).
Nix will perform derivations on those machines via SSH by copying the
inputs to the Nix store on the remote machine, starting the build,
then copying the output back to the local Nix store.
'';
};
distributedBuilds = mkOption {
type = types.bool;
default = false;
description = lib.mdDoc ''
Whether to distribute builds to the machines listed in
{option}`nix.buildMachines`.
'';
};
};
};
# distributedBuilds does *not* inhibit /etc/machines generation; caller may
# override that nix option.
config = mkIf cfg.enable {
assertions =
let badMachine = m: m.system == null && m.systems == [ ];
in
[
{
assertion = !(any badMachine cfg.buildMachines);
message = ''
At least one system type (via <varname>system</varname> or
<varname>systems</varname>) must be set for every build machine.
Invalid machine specifications:
'' + " " +
(concatStringsSep "\n "
(map (m: m.hostName)
(filter (badMachine) cfg.buildMachines)));
}
];
# List of machines for distributed Nix builds
environment.etc."nix/machines" =
mkIf (cfg.buildMachines != [ ]) {
text = buildMachinesText;
};
# Legacy configuration conversion.
nix.settings = mkIf (!cfg.distributedBuilds) { builders = null; };
};
}

379
nixos/modules/config/nix.nix Normal file
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@ -0,0 +1,379 @@
/*
Manages /etc/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
floatToString
getVersion
isBool
isDerivation
isFloat
isInt
isList
isString
literalExpression
mapAttrsToList
mkAfter
mkDefault
mkIf
mkOption
mkRenamedOptionModuleWith
optionalString
optionals
strings
systems
toPretty
types
versionAtLeast
;
cfg = config.nix;
nixPackage = cfg.package.out;
isNixAtLeast = versionAtLeast (getVersion nixPackage);
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);
in
pkgs.writeTextFile {
name = "nix.conf";
text = ''
# WARNING: this file is generated from the nix.* options in
# your NixOS configuration, typically
# /etc/nixos/configuration.nix. Do not edit it!
${mkKeyValuePairs cfg.settings}
${cfg.extraOptions}
'';
checkPhase = lib.optionalString cfg.checkConfig (
if pkgs.stdenv.hostPlatform != pkgs.stdenv.buildPlatform then ''
echo "Ignoring validation for cross-compilation"
''
else ''
echo "Validating generated nix.conf"
ln -s $out ./nix.conf
set -e
set +o pipefail
NIX_CONF_DIR=$PWD \
${cfg.package}/bin/nix show-config ${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 = lib.mdDoc ''
If enabled, checks that Nix can parse the generated nix.conf.
'';
};
checkAllErrors = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
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 = lib.mdDoc "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 = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
Directories from the host filesystem to be included
in the sandbox.
'';
};
substituters = mkOption {
type = types.listOf types.str;
description = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
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;
default = [ "root" ];
example = [ "root" "alice" "@wheel" ];
description = lib.mdDoc ''
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;
example = [ "kvm" "big-parallel" "gccarch-skylake" ];
description = lib.mdDoc ''
The set of features supported by the machine. Derivations
can express dependencies on system features through the
`requiredSystemFeatures` attribute.
By default, pseudo-features `nixos-test`, `benchmark`,
and `big-parallel` used in Nixpkgs are set, `kvm`
is also included if it is available.
'';
};
allowed-users = mkOption {
type = types.listOf types.str;
default = [ "*" ];
example = [ "@wheel" "@builders" "alice" "bob" ];
description = lib.mdDoc ''
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;
system-features = [ "big-parallel" "kvm" "recursive-nix" ];
sandbox-paths = { "/bin/sh" = "''${pkgs.busybox-sandbox-shell.out}/bin/busybox"; };
}
'';
description = lib.mdDoc ''
Configuration for Nix, see
<https://nixos.org/manual/nix/stable/command-ref/conf-file.html> or
{manpage}`nix.conf(5)` for available options.
The value declared here will be translated directly to the key-value pairs Nix expects.
You can use {command}`nix-instantiate --eval --strict '<nixpkgs/nixos>' -A config.nix.settings`
to view the current value. By default it is empty.
Nix configurations defined under {option}`nix.*` will be translated and applied to this
option. In addition, configuration specified in {option}`nix.extraOptions` will be appended
verbatim to the resulting config file.
'';
};
};
};
config = mkIf cfg.enable {
environment.etc."nix/nix.conf".source = nixConf;
nix.settings = {
trusted-public-keys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
substituters = mkAfter [ "https://cache.nixos.org/" ];
system-features = mkDefault (
[ "nixos-test" "benchmark" "big-parallel" "kvm" ] ++
optionals (pkgs.stdenv.hostPlatform ? gcc.arch) (
# a builder can run code for `gcc.arch` and inferior architectures
[ "gccarch-${pkgs.stdenv.hostPlatform.gcc.arch}" ] ++
map (x: "gccarch-${x}") (systems.architectures.inferiors.${pkgs.stdenv.hostPlatform.gcc.arch} or [])
)
);
};
};
}

7
nixos/modules/misc/version.nix
View file

@ -140,13 +140,6 @@ in
'';
};
defaultChannel = mkOption {
internal = true;
type = types.str;
default = "https://nixos.org/channels/nixos-unstable";
description = lib.mdDoc "Default NixOS channel to which the root user is subscribed.";
};
configurationRevision = mkOption {
type = types.nullOr types.str;
default = null;

6
nixos/modules/module-list.nix
View file

@ -16,6 +16,10 @@
./config/malloc.nix
./config/mysql.nix
./config/networking.nix
./config/nix.nix
./config/nix-channel.nix
./config/nix-flakes.nix
./config/nix-remote-build.nix
./config/no-x-libs.nix
./config/nsswitch.nix
./config/power-management.nix
@ -661,7 +665,6 @@
./services/misc/moonraker.nix
./services/misc/n8n.nix
./services/misc/nitter.nix
./services/misc/nix-daemon.nix
./services/misc/nix-gc.nix
./services/misc/nix-optimise.nix
./services/misc/nix-ssh-serve.nix
@ -1143,6 +1146,7 @@
./services/system/earlyoom.nix
./services/system/kerberos/default.nix
./services/system/localtimed.nix
./services/system/nix-daemon.nix
./services/system/nscd.nix
./services/system/saslauthd.nix
./services/system/self-deploy.nix

844
nixos/modules/services/misc/nix-daemon.nix
View file

@ -1,844 +0,0 @@
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.nix;
nixPackage = cfg.package.out;
isNixAtLeast = versionAtLeast (getVersion nixPackage);
makeNixBuildUser = nr: {
name = "nixbld${toString nr}";
value = {
description = "Nix build user ${toString nr}";
/*
For consistency with the setgid(2), setuid(2), and setgroups(2)
calls in `libstore/build.cc', don't add any supplementary group
here except "nixbld".
*/
uid = builtins.add config.ids.uids.nixbld nr;
isSystemUser = true;
group = "nixbld";
extraGroups = [ "nixbld" ];
};
};
nixbldUsers = listToAttrs (map makeNixBuildUser (range 1 cfg.nrBuildUsers));
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);
in
pkgs.writeTextFile {
name = "nix.conf";
text = ''
# WARNING: this file is generated from the nix.* options in
# your NixOS configuration, typically
# /etc/nixos/configuration.nix. Do not edit it!
${mkKeyValuePairs cfg.settings}
${cfg.extraOptions}
'';
checkPhase = lib.optionalString cfg.checkConfig (
if pkgs.stdenv.hostPlatform != pkgs.stdenv.buildPlatform then ''
echo "Ignoring validation for cross-compilation"
''
else ''
echo "Validating generated nix.conf"
ln -s $out ./nix.conf
set -e
set +o pipefail
NIX_CONF_DIR=$PWD \
${cfg.package}/bin/nix show-config ${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
'');
};
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));
in
{
imports = [
(mkRenamedOptionModuleWith { sinceRelease = 2003; from = [ "nix" "useChroot" ]; to = [ "nix" "useSandbox" ]; })
(mkRenamedOptionModuleWith { sinceRelease = 2003; from = [ "nix" "chrootDirs" ]; to = [ "nix" "sandboxPaths" ]; })
(mkRenamedOptionModuleWith { sinceRelease = 2205; from = [ "nix" "daemonIONiceLevel" ]; to = [ "nix" "daemonIOSchedPriority" ]; })
(mkRenamedOptionModuleWith { sinceRelease = 2211; from = [ "nix" "readOnlyStore" ]; to = [ "boot" "readOnlyNixStore" ]; })
(mkRemovedOptionModule [ "nix" "daemonNiceLevel" ] "Consider nix.daemonCPUSchedPolicy instead.")
] ++ mapAttrsToList (oldConf: newConf: mkRenamedOptionModuleWith { sinceRelease = 2205; from = [ "nix" oldConf ]; to = [ "nix" "settings" newConf ]; }) legacyConfMappings;
###### interface
options = {
nix = {
enable = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Whether to enable Nix.
Disabling Nix makes the system hard to modify and the Nix programs and configuration will not be made available by NixOS itself.
'';
};
package = mkOption {
type = types.package;
default = pkgs.nix;
defaultText = literalExpression "pkgs.nix";
description = lib.mdDoc ''
This option specifies the Nix package instance to use throughout the system.
'';
};
distributedBuilds = mkOption {
type = types.bool;
default = false;
description = lib.mdDoc ''
Whether to distribute builds to the machines listed in
{option}`nix.buildMachines`.
'';
};
daemonCPUSchedPolicy = mkOption {
type = types.enum [ "other" "batch" "idle" ];
default = "other";
example = "batch";
description = lib.mdDoc ''
Nix daemon process CPU scheduling policy. This policy propagates to
build processes. `other` is the default scheduling
policy for regular tasks. The `batch` policy is
similar to `other`, but optimised for
non-interactive tasks. `idle` is for extremely
low-priority tasks that should only be run when no other task
requires CPU time.
Please note that while using the `idle` policy may
greatly improve responsiveness of a system performing expensive
builds, it may also slow down and potentially starve crucial
configuration updates during load.
`idle` may therefore be a sensible policy for
systems that experience only intermittent phases of high CPU load,
such as desktop or portable computers used interactively. Other
systems should use the `other` or
`batch` policy instead.
For more fine-grained resource control, please refer to
{manpage}`systemd.resource-control(5)` and adjust
{option}`systemd.services.nix-daemon` directly.
'';
};
daemonIOSchedClass = mkOption {
type = types.enum [ "best-effort" "idle" ];
default = "best-effort";
example = "idle";
description = lib.mdDoc ''
Nix daemon process I/O scheduling class. This class propagates to
build processes. `best-effort` is the default
class for regular tasks. The `idle` class is for
extremely low-priority tasks that should only perform I/O when no
other task does.
Please note that while using the `idle` scheduling
class can improve responsiveness of a system performing expensive
builds, it might also slow down or starve crucial configuration
updates during load.
`idle` may therefore be a sensible class for
systems that experience only intermittent phases of high I/O load,
such as desktop or portable computers used interactively. Other
systems should use the `best-effort` class.
'';
};
daemonIOSchedPriority = mkOption {
type = types.int;
default = 4;
example = 1;
description = lib.mdDoc ''
Nix daemon process I/O scheduling priority. This priority propagates
to build processes. The supported priorities depend on the
scheduling policy: With idle, priorities are not used in scheduling
decisions. best-effort supports values in the range 0 (high) to 7
(low).
'';
};
buildMachines = mkOption {
type = types.listOf (types.submodule {
options = {
hostName = mkOption {
type = types.str;
example = "nixbuilder.example.org";
description = lib.mdDoc ''
The hostname of the build machine.
'';
};
protocol = mkOption {
type = types.enum [ null "ssh" "ssh-ng" ];
default = "ssh";
example = "ssh-ng";
description = lib.mdDoc ''
The protocol used for communicating with the build machine.
Use `ssh-ng` if your remote builder and your
local Nix version support that improved protocol.
Use `null` when trying to change the special localhost builder
without a protocol which is for example used by hydra.
'';
};
system = mkOption {
type = types.nullOr types.str;
default = null;
example = "x86_64-linux";
description = lib.mdDoc ''
The system type the build machine can execute derivations on.
Either this attribute or {var}`systems` must be
present, where {var}`system` takes precedence if
both are set.
'';
};
systems = mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "x86_64-linux" "aarch64-linux" ];
description = lib.mdDoc ''
The system types the build machine can execute derivations on.
Either this attribute or {var}`system` must be
present, where {var}`system` takes precedence if
both are set.
'';
};
sshUser = mkOption {
type = types.nullOr types.str;
default = null;
example = "builder";
description = lib.mdDoc ''
The username to log in as on the remote host. This user must be
able to log in and run nix commands non-interactively. It must
also be privileged to build derivations, so must be included in
{option}`nix.settings.trusted-users`.
'';
};
sshKey = mkOption {
type = types.nullOr types.str;
default = null;
example = "/root/.ssh/id_buildhost_builduser";
description = lib.mdDoc ''
The path to the SSH private key with which to authenticate on
the build machine. The private key must not have a passphrase.
If null, the building user (root on NixOS machines) must have an
appropriate ssh configuration to log in non-interactively.
Note that for security reasons, this path must point to a file
in the local filesystem, *not* to the nix store.
'';
};
maxJobs = mkOption {
type = types.int;
default = 1;
description = lib.mdDoc ''
The number of concurrent jobs the build machine supports. The
build machine will enforce its own limits, but this allows hydra
to schedule better since there is no work-stealing between build
machines.
'';
};
speedFactor = mkOption {
type = types.int;
default = 1;
description = lib.mdDoc ''
The relative speed of this builder. This is an arbitrary integer
that indicates the speed of this builder, relative to other
builders. Higher is faster.
'';
};
mandatoryFeatures = mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "big-parallel" ];
description = lib.mdDoc ''
A list of features mandatory for this builder. The builder will
be ignored for derivations that don't require all features in
this list. All mandatory features are automatically included in
{var}`supportedFeatures`.
'';
};
supportedFeatures = mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "kvm" "big-parallel" ];
description = lib.mdDoc ''
A list of features supported by this builder. The builder will
be ignored for derivations that require features not in this
list.
'';
};
publicHostKey = mkOption {
type = types.nullOr types.str;
default = null;
description = lib.mdDoc ''
The (base64-encoded) public host key of this builder. The field
is calculated via {command}`base64 -w0 /etc/ssh/ssh_host_type_key.pub`.
If null, SSH will use its regular known-hosts file when connecting.
'';
};
};
});
default = [ ];
description = lib.mdDoc ''
This option lists the machines to be used if distributed builds are
enabled (see {option}`nix.distributedBuilds`).
Nix will perform derivations on those machines via SSH by copying the
inputs to the Nix store on the remote machine, starting the build,
then copying the output back to the local Nix store.
'';
};
# Environment variables for running Nix.
envVars = mkOption {
type = types.attrs;
internal = true;
default = { };
description = lib.mdDoc "Environment variables used by Nix.";
};
nrBuildUsers = mkOption {
type = types.int;
description = lib.mdDoc ''
Number of `nixbld` user accounts created to
perform secure concurrent builds. If you receive an error
message saying that “all build users are currently in use”,
you should increase this value.
'';
};
nixPath = mkOption {
type = types.listOf types.str;
default = [
"nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
"nixos-config=/etc/nixos/configuration.nix"
"/nix/var/nix/profiles/per-user/root/channels"
];
description = lib.mdDoc ''
The default Nix expression search path, used by the Nix
evaluator to look up paths enclosed in angle brackets
(e.g. `<nixpkgs>`).
'';
};
checkConfig = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
If enabled, checks that Nix can parse the generated nix.conf.
'';
};
checkAllErrors = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
If enabled, checks the nix.conf parsing for any kind of error. When disabled, checks only for unknown settings.
'';
};
registry = mkOption {
type = types.attrsOf (types.submodule (
let
referenceAttrs = with types; attrsOf (oneOf [
str
int
bool
path
package
]);
in
{ config, name, ... }:
{
options = {
from = mkOption {
type = referenceAttrs;
example = { type = "indirect"; id = "nixpkgs"; };
description = lib.mdDoc "The flake reference to be rewritten.";
};
to = mkOption {
type = referenceAttrs;
example = { type = "github"; owner = "my-org"; repo = "my-nixpkgs"; };
description = lib.mdDoc "The flake reference {option}`from` is rewritten to.";
};
flake = mkOption {
type = types.nullOr types.attrs;
default = null;
example = literalExpression "nixpkgs";
description = lib.mdDoc ''
The flake input {option}`from` is rewritten to.
'';
};
exact = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Whether the {option}`from` reference needs to match exactly. If set,
a {option}`from` reference like `nixpkgs` does not
match with a reference like `nixpkgs/nixos-20.03`.
'';
};
};
config = {
from = mkDefault { type = "indirect"; id = name; };
to = mkIf (config.flake != null) (mkDefault (
{
type = "path";
path = config.flake.outPath;
} // filterAttrs
(n: _: n == "lastModified" || n == "rev" || n == "revCount" || n == "narHash")
config.flake
));
};
}
));
default = { };
description = lib.mdDoc ''
A system-wide flake registry.
'';
};
extraOptions = mkOption {
type = types.lines;
default = "";
example = ''
keep-outputs = true
keep-derivations = true
'';
description = lib.mdDoc "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 = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
Directories from the host filesystem to be included
in the sandbox.
'';
};
substituters = mkOption {
type = types.listOf types.str;
description = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
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 = lib.mdDoc ''
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;
default = [ "root" ];
example = [ "root" "alice" "@wheel" ];
description = lib.mdDoc ''
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;
example = [ "kvm" "big-parallel" "gccarch-skylake" ];
description = lib.mdDoc ''
The set of features supported by the machine. Derivations
can express dependencies on system features through the
`requiredSystemFeatures` attribute.
By default, pseudo-features `nixos-test`, `benchmark`,
and `big-parallel` used in Nixpkgs are set, `kvm`
is also included if it is available.
'';
};
allowed-users = mkOption {
type = types.listOf types.str;
default = [ "*" ];
example = [ "@wheel" "@builders" "alice" "bob" ];
description = lib.mdDoc ''
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;
system-features = [ "big-parallel" "kvm" "recursive-nix" ];
sandbox-paths = { "/bin/sh" = "''${pkgs.busybox-sandbox-shell.out}/bin/busybox"; };
}
'';
description = lib.mdDoc ''
Configuration for Nix, see
<https://nixos.org/manual/nix/stable/command-ref/conf-file.html> or
{manpage}`nix.conf(5)` for available options.
The value declared here will be translated directly to the key-value pairs Nix expects.
You can use {command}`nix-instantiate --eval --strict '<nixpkgs/nixos>' -A config.nix.settings`
to view the current value. By default it is empty.
Nix configurations defined under {option}`nix.*` will be translated and applied to this
option. In addition, configuration specified in {option}`nix.extraOptions` will be appended
verbatim to the resulting config file.
'';
};
};
};
###### implementation
config = mkIf cfg.enable {
environment.systemPackages =
[
nixPackage
pkgs.nix-info
]
++ optional (config.programs.bash.enableCompletion) pkgs.nix-bash-completions;
environment.etc."nix/nix.conf".source = nixConf;
environment.etc."nix/registry.json".text = builtins.toJSON {
version = 2;
flakes = mapAttrsToList (n: v: { inherit (v) from to exact; }) cfg.registry;
};
# List of machines for distributed Nix builds in the format
# expected by build-remote.pl.
environment.etc."nix/machines" = mkIf (cfg.buildMachines != [ ]) {
text =
concatMapStrings
(machine:
(concatStringsSep " " ([
"${optionalString (machine.protocol != null) "${machine.protocol}://"}${optionalString (machine.sshUser != null) "${machine.sshUser}@"}${machine.hostName}"
(if machine.system != null then machine.system else if machine.systems != [ ] then concatStringsSep "," machine.systems else "-")
(if machine.sshKey != null then machine.sshKey else "-")
(toString machine.maxJobs)
(toString machine.speedFactor)
(let res = (machine.supportedFeatures ++ machine.mandatoryFeatures);
in if (res == []) then "-" else (concatStringsSep "," res))
(let res = machine.mandatoryFeatures;
in if (res == []) then "-" else (concatStringsSep "," machine.mandatoryFeatures))
]
++ optional (isNixAtLeast "2.4pre") (if machine.publicHostKey != null then machine.publicHostKey else "-")))
+ "\n"
)
cfg.buildMachines;
};
assertions =
let badMachine = m: m.system == null && m.systems == [ ];
in
[
{
assertion = !(any badMachine cfg.buildMachines);
message = ''
At least one system type (via <varname>system</varname> or
<varname>systems</varname>) must be set for every build machine.
Invalid machine specifications:
'' + " " +
(concatStringsSep "\n "
(map (m: m.hostName)
(filter (badMachine) cfg.buildMachines)));
}
];
systemd.packages = [ nixPackage ];
# Will only work once https://github.com/NixOS/nix/pull/6285 is merged
# systemd.tmpfiles.packages = [ nixPackage ];
# Can be dropped for Nix > https://github.com/NixOS/nix/pull/6285
systemd.tmpfiles.rules = [
"d /nix/var/nix/daemon-socket 0755 root root - -"
];
systemd.sockets.nix-daemon.wantedBy = [ "sockets.target" ];
systemd.services.nix-daemon =
{
path = [ nixPackage pkgs.util-linux config.programs.ssh.package ]
++ optionals cfg.distributedBuilds [ pkgs.gzip ];
environment = cfg.envVars
// { CURL_CA_BUNDLE = "/etc/ssl/certs/ca-certificates.crt"; }
// config.networking.proxy.envVars;
unitConfig.RequiresMountsFor = "/nix/store";
serviceConfig =
{
CPUSchedulingPolicy = cfg.daemonCPUSchedPolicy;
IOSchedulingClass = cfg.daemonIOSchedClass;
IOSchedulingPriority = cfg.daemonIOSchedPriority;
LimitNOFILE = 1048576;
};
restartTriggers = [ nixConf ];
# `stopIfChanged = false` changes to switch behavior
# from stop -> update units -> start
# to update units -> restart
#
# The `stopIfChanged` setting therefore controls a trade-off between a
# more predictable lifecycle, which runs the correct "version" of
# the `ExecStop` line, and on the other hand the availability of
# sockets during the switch, as the effectiveness of the stop operation
# depends on the socket being stopped as well.
#
# As `nix-daemon.service` does not make use of `ExecStop`, we prefer
# to keep the socket up and available. This is important for machines
# that run Nix-based services, such as automated build, test, and deploy
# services, that expect the daemon socket to be available at all times.
#
# Notably, the Nix client does not retry on failure to connect to the
# daemon socket, and the in-process RemoteStore instance will disable
# itself. This makes retries infeasible even for services that are
# aware of the issue. Failure to connect can affect not only new client
# processes, but also new RemoteStore instances in existing processes,
# as well as existing RemoteStore instances that have not saturated
# their connection pool.
#
# Also note that `stopIfChanged = true` does not kill existing
# connection handling daemons, as one might wish to happen before a
# breaking Nix upgrade (which is rare). The daemon forks that handle
# the individual connections split off into their own sessions, causing
# them not to be stopped by systemd.
# If a Nix upgrade does require all existing daemon processes to stop,
# nix-daemon must do so on its own accord, and only when the new version
# starts and detects that Nix's persistent state needs an upgrade.
stopIfChanged = false;
};
# Set up the environment variables for running Nix.
environment.sessionVariables = cfg.envVars // { NIX_PATH = cfg.nixPath; };
environment.extraInit =
''
if [ -e "$HOME/.nix-defexpr/channels" ]; then
export NIX_PATH="$HOME/.nix-defexpr/channels''${NIX_PATH:+:$NIX_PATH}"
fi
'';
nix.nrBuildUsers = mkDefault (
if cfg.settings.auto-allocate-uids or false then 0
else max 32 (if cfg.settings.max-jobs == "auto" then 0 else cfg.settings.max-jobs)
);
users.users = nixbldUsers;
services.xserver.displayManager.hiddenUsers = attrNames nixbldUsers;
system.activationScripts.nix = stringAfter [ "etc" "users" ]
''
install -m 0755 -d /nix/var/nix/{gcroots,profiles}/per-user
# Subscribe the root user to the NixOS channel by default.
if [ ! -e "/root/.nix-channels" ]; then
echo "${config.system.defaultChannel} nixos" > "/root/.nix-channels"
fi
'';
# Legacy configuration conversion.
nix.settings = mkMerge [
{
trusted-public-keys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
substituters = mkAfter [ "https://cache.nixos.org/" ];
system-features = mkDefault (
[ "nixos-test" "benchmark" "big-parallel" "kvm" ] ++
optionals (pkgs.stdenv.hostPlatform ? gcc.arch) (
# a builder can run code for `gcc.arch` and inferior architectures
[ "gccarch-${pkgs.stdenv.hostPlatform.gcc.arch}" ] ++
map (x: "gccarch-${x}") (systems.architectures.inferiors.${pkgs.stdenv.hostPlatform.gcc.arch} or [])
)
);
}
(mkIf (!cfg.distributedBuilds) { builders = null; })
(mkIf (isNixAtLeast "2.3pre") { sandbox-fallback = false; })
];
};
}

263
nixos/modules/services/system/nix-daemon.nix Normal file
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@ -0,0 +1,263 @@
/*
Declares what makes the nix-daemon work on systemd.
See also
- nixos/modules/config/nix.nix: the nix.conf
- nixos/modules/config/nix-remote-build.nix: the nix.conf
*/
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.nix;
nixPackage = cfg.package.out;
isNixAtLeast = versionAtLeast (getVersion nixPackage);
makeNixBuildUser = nr: {
name = "nixbld${toString nr}";
value = {
description = "Nix build user ${toString nr}";
/*
For consistency with the setgid(2), setuid(2), and setgroups(2)
calls in `libstore/build.cc', don't add any supplementary group
here except "nixbld".
*/
uid = builtins.add config.ids.uids.nixbld nr;
isSystemUser = true;
group = "nixbld";
extraGroups = [ "nixbld" ];
};
};
nixbldUsers = listToAttrs (map makeNixBuildUser (range 1 cfg.nrBuildUsers));
in
{
imports = [
../../config/nix.nix
(mkRenamedOptionModuleWith { sinceRelease = 2205; from = [ "nix" "daemonIONiceLevel" ]; to = [ "nix" "daemonIOSchedPriority" ]; })
(mkRenamedOptionModuleWith { sinceRelease = 2211; from = [ "nix" "readOnlyStore" ]; to = [ "boot" "readOnlyNixStore" ]; })
(mkRemovedOptionModule [ "nix" "daemonNiceLevel" ] "Consider nix.daemonCPUSchedPolicy instead.")
];
###### interface
options = {
nix = {
enable = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Whether to enable Nix.
Disabling Nix makes the system hard to modify and the Nix programs and configuration will not be made available by NixOS itself.
'';
};
package = mkOption {
type = types.package;
default = pkgs.nix;
defaultText = literalExpression "pkgs.nix";
description = lib.mdDoc ''
This option specifies the Nix package instance to use throughout the system.
'';
};
daemonCPUSchedPolicy = mkOption {
type = types.enum [ "other" "batch" "idle" ];
default = "other";
example = "batch";
description = lib.mdDoc ''
Nix daemon process CPU scheduling policy. This policy propagates to
build processes. `other` is the default scheduling
policy for regular tasks. The `batch` policy is
similar to `other`, but optimised for
non-interactive tasks. `idle` is for extremely
low-priority tasks that should only be run when no other task
requires CPU time.
Please note that while using the `idle` policy may
greatly improve responsiveness of a system performing expensive
builds, it may also slow down and potentially starve crucial
configuration updates during load.
`idle` may therefore be a sensible policy for
systems that experience only intermittent phases of high CPU load,
such as desktop or portable computers used interactively. Other
systems should use the `other` or
`batch` policy instead.
For more fine-grained resource control, please refer to
{manpage}`systemd.resource-control(5)` and adjust
{option}`systemd.services.nix-daemon` directly.
'';
};
daemonIOSchedClass = mkOption {
type = types.enum [ "best-effort" "idle" ];
default = "best-effort";
example = "idle";
description = lib.mdDoc ''
Nix daemon process I/O scheduling class. This class propagates to
build processes. `best-effort` is the default
class for regular tasks. The `idle` class is for
extremely low-priority tasks that should only perform I/O when no
other task does.
Please note that while using the `idle` scheduling
class can improve responsiveness of a system performing expensive
builds, it might also slow down or starve crucial configuration
updates during load.
`idle` may therefore be a sensible class for
systems that experience only intermittent phases of high I/O load,
such as desktop or portable computers used interactively. Other
systems should use the `best-effort` class.
'';
};
daemonIOSchedPriority = mkOption {
type = types.int;
default = 4;
example = 1;
description = lib.mdDoc ''
Nix daemon process I/O scheduling priority. This priority propagates
to build processes. The supported priorities depend on the
scheduling policy: With idle, priorities are not used in scheduling
decisions. best-effort supports values in the range 0 (high) to 7
(low).
'';
};
# Environment variables for running Nix.
envVars = mkOption {
type = types.attrs;
internal = true;
default = { };
description = lib.mdDoc "Environment variables used by Nix.";
};
nrBuildUsers = mkOption {
type = types.int;
description = lib.mdDoc ''
Number of `nixbld` user accounts created to
perform secure concurrent builds. If you receive an error
message saying that “all build users are currently in use”,
you should increase this value.
'';
};
};
};
###### implementation
config = mkIf cfg.enable {
environment.systemPackages =
[
nixPackage
pkgs.nix-info
]
++ optional (config.programs.bash.enableCompletion) pkgs.nix-bash-completions;
systemd.packages = [ nixPackage ];
# Will only work once https://github.com/NixOS/nix/pull/6285 is merged
# systemd.tmpfiles.packages = [ nixPackage ];
# Can be dropped for Nix > https://github.com/NixOS/nix/pull/6285
systemd.tmpfiles.rules = [
"d /nix/var/nix/daemon-socket 0755 root root - -"
];
systemd.sockets.nix-daemon.wantedBy = [ "sockets.target" ];
systemd.services.nix-daemon =
{
path = [ nixPackage pkgs.util-linux config.programs.ssh.package ]
++ optionals cfg.distributedBuilds [ pkgs.gzip ];
environment = cfg.envVars
// { CURL_CA_BUNDLE = "/etc/ssl/certs/ca-certificates.crt"; }
// config.networking.proxy.envVars;
unitConfig.RequiresMountsFor = "/nix/store";
serviceConfig =
{
CPUSchedulingPolicy = cfg.daemonCPUSchedPolicy;
IOSchedulingClass = cfg.daemonIOSchedClass;
IOSchedulingPriority = cfg.daemonIOSchedPriority;
LimitNOFILE = 1048576;
};
restartTriggers = [ config.environment.etc."nix/nix.conf".source ];
# `stopIfChanged = false` changes to switch behavior
# from stop -> update units -> start
# to update units -> restart
#
# The `stopIfChanged` setting therefore controls a trade-off between a
# more predictable lifecycle, which runs the correct "version" of
# the `ExecStop` line, and on the other hand the availability of
# sockets during the switch, as the effectiveness of the stop operation
# depends on the socket being stopped as well.
#
# As `nix-daemon.service` does not make use of `ExecStop`, we prefer
# to keep the socket up and available. This is important for machines
# that run Nix-based services, such as automated build, test, and deploy
# services, that expect the daemon socket to be available at all times.
#
# Notably, the Nix client does not retry on failure to connect to the
# daemon socket, and the in-process RemoteStore instance will disable
# itself. This makes retries infeasible even for services that are
# aware of the issue. Failure to connect can affect not only new client
# processes, but also new RemoteStore instances in existing processes,
# as well as existing RemoteStore instances that have not saturated
# their connection pool.
#
# Also note that `stopIfChanged = true` does not kill existing
# connection handling daemons, as one might wish to happen before a
# breaking Nix upgrade (which is rare). The daemon forks that handle
# the individual connections split off into their own sessions, causing
# them not to be stopped by systemd.
# If a Nix upgrade does require all existing daemon processes to stop,
# nix-daemon must do so on its own accord, and only when the new version
# starts and detects that Nix's persistent state needs an upgrade.
stopIfChanged = false;
};
# Set up the environment variables for running Nix.
environment.sessionVariables = cfg.envVars;
nix.nrBuildUsers = mkDefault (
if cfg.settings.auto-allocate-uids or false then 0
else max 32 (if cfg.settings.max-jobs == "auto" then 0 else cfg.settings.max-jobs)
);
users.users = nixbldUsers;
services.xserver.displayManager.hiddenUsers = attrNames nixbldUsers;
system.activationScripts.nix = stringAfter [ "etc" "users" ]
''
install -m 0755 -d /nix/var/nix/{gcroots,profiles}/per-user
'';
# Legacy configuration conversion.
nix.settings = mkMerge [
(mkIf (isNixAtLeast "2.3pre") { sandbox-fallback = false; })
];
};
}