nixpkgs/nixos/lib/systemd-unit-options.nix
r-vdp 9258f57625
systemd: add a name option to all systemd units
This allows us to set things like dependencies in a way that we can
catch typos at eval time.
So instead of
```nix
systemd.services.foo.wants = [ "bar.service" ];
```
we can write
```nix
systemd.services.foo.wants = [ config.systemd.services.bar.name ];
```
which will throw an error if no such service has been defined.

Not all cases can be done like this (eg template services), but in a lot
of cases this will allow to avoid typos.

There is a matching option on the unit option
(`systemd.units."foo.service".name`) as well.
2024-04-15 11:32:45 +02:00

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{ lib, systemdUtils }:
let
inherit (systemdUtils.lib)
assertValueOneOf
automountConfig
checkUnitConfig
makeJobScript
mountConfig
serviceConfig
unitConfig
unitNameType
;
inherit (lib)
any
concatMap
filterOverrides
isList
mergeEqualOption
mkIf
mkMerge
mkOption
mkOptionType
singleton
toList
types
;
checkService = checkUnitConfig "Service" [
(assertValueOneOf "Type" [
"exec" "simple" "forking" "oneshot" "dbus" "notify" "notify-reload" "idle"
])
(assertValueOneOf "Restart" [
"no" "on-success" "on-failure" "on-abnormal" "on-abort" "always"
])
];
in rec {
unitOption = mkOptionType {
name = "systemd option";
merge = loc: defs:
let
defs' = filterOverrides defs;
in
if any (def: isList def.value) defs'
then concatMap (def: toList def.value) defs'
else mergeEqualOption loc defs';
};
sharedOptions = {
enable = mkOption {
default = true;
type = types.bool;
description = ''
If set to false, this unit will be a symlink to
/dev/null. This is primarily useful to prevent specific
template instances
(e.g. `serial-getty@ttyS0`) from being
started. Note that `enable=true` does not
make a unit start by default at boot; if you want that, see
`wantedBy`.
'';
};
name = lib.mkOption {
type = lib.types.str;
description = ''
The name of this systemd unit, including its extension.
This can be used to refer to this unit from other systemd units.
'';
};
overrideStrategy = mkOption {
default = "asDropinIfExists";
type = types.enum [ "asDropinIfExists" "asDropin" ];
description = ''
Defines how unit configuration is provided for systemd:
`asDropinIfExists` creates a unit file when no unit file is provided by the package
otherwise a drop-in file name `overrides.conf`.
`asDropin` creates a drop-in file named `overrides.conf`.
Mainly needed to define instances for systemd template units (e.g. `systemd-nspawn@mycontainer.service`).
See also {manpage}`systemd.unit(5)`.
'';
};
requiredBy = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
Units that require (i.e. depend on and need to go down with) this unit.
As discussed in the `wantedBy` option description this also creates
`.requires` symlinks automatically.
'';
};
upheldBy = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
Keep this unit running as long as the listed units are running. This is a continuously
enforced version of wantedBy.
'';
};
wantedBy = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
Units that want (i.e. depend on) this unit. The default method for
starting a unit by default at boot time is to set this option to
`["multi-user.target"]` for system services. Likewise for user units
(`systemd.user.<name>.*`) set it to `["default.target"]` to make a unit
start by default when the user `<name>` logs on.
This option creates a `.wants` symlink in the given target that exists
statelessly without the need for running `systemctl enable`.
The `[Install]` section described in {manpage}`systemd.unit(5)` however is
not supported because it is a stateful process that does not fit well
into the NixOS design.
'';
};
aliases = mkOption {
default = [];
type = types.listOf unitNameType;
description = "Aliases of that unit.";
};
};
concreteUnitOptions = sharedOptions // {
text = mkOption {
type = types.nullOr types.str;
default = null;
description = "Text of this systemd unit.";
};
unit = mkOption {
internal = true;
description = "The generated unit.";
};
};
commonUnitOptions = {
options = sharedOptions // {
description = mkOption {
default = "";
type = types.singleLineStr;
description = "Description of this unit used in systemd messages and progress indicators.";
};
documentation = mkOption {
default = [];
type = types.listOf types.str;
description = "A list of URIs referencing documentation for this unit or its configuration.";
};
requires = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
Start the specified units when this unit is started, and stop
this unit when the specified units are stopped or fail.
'';
};
wants = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
Start the specified units when this unit is started.
'';
};
upholds = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
Keeps the specified running while this unit is running. A continuous version of `wants`.
'';
};
after = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
If the specified units are started at the same time as
this unit, delay this unit until they have started.
'';
};
before = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
If the specified units are started at the same time as
this unit, delay them until this unit has started.
'';
};
bindsTo = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
Like requires, but in addition, if the specified units
unexpectedly disappear, this unit will be stopped as well.
'';
};
partOf = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
If the specified units are stopped or restarted, then this
unit is stopped or restarted as well.
'';
};
conflicts = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
If the specified units are started, then this unit is stopped
and vice versa.
'';
};
requisite = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
Similar to requires. However if the units listed are not started,
they will not be started and the transaction will fail.
'';
};
unitConfig = mkOption {
default = {};
example = { RequiresMountsFor = "/data"; };
type = types.attrsOf unitOption;
description = ''
Each attribute in this set specifies an option in the
`[Unit]` section of the unit. See
{manpage}`systemd.unit(5)` for details.
'';
};
onFailure = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
A list of one or more units that are activated when
this unit enters the "failed" state.
'';
};
onSuccess = mkOption {
default = [];
type = types.listOf unitNameType;
description = ''
A list of one or more units that are activated when
this unit enters the "inactive" state.
'';
};
startLimitBurst = mkOption {
type = types.int;
description = ''
Configure unit start rate limiting. Units which are started
more than startLimitBurst times within an interval time
interval are not permitted to start any more.
'';
};
startLimitIntervalSec = mkOption {
type = types.int;
description = ''
Configure unit start rate limiting. Units which are started
more than startLimitBurst times within an interval time
interval are not permitted to start any more.
'';
};
};
};
stage2CommonUnitOptions = {
imports = [
commonUnitOptions
];
options = {
restartTriggers = mkOption {
default = [];
type = types.listOf types.unspecified;
description = ''
An arbitrary list of items such as derivations. If any item
in the list changes between reconfigurations, the service will
be restarted.
'';
};
reloadTriggers = mkOption {
default = [];
type = types.listOf unitOption;
description = ''
An arbitrary list of items such as derivations. If any item
in the list changes between reconfigurations, the service will
be reloaded. If anything but a reload trigger changes in the
unit file, the unit will be restarted instead.
'';
};
};
};
stage1CommonUnitOptions = commonUnitOptions;
serviceOptions = { name, config, ... }: {
options = {
environment = mkOption {
default = {};
type = with types; attrsOf (nullOr (oneOf [ str path package ]));
example = { PATH = "/foo/bar/bin"; LANG = "nl_NL.UTF-8"; };
description = "Environment variables passed to the service's processes.";
};
path = mkOption {
default = [];
type = with types; listOf (oneOf [ package str ]);
description = ''
Packages added to the service's {env}`PATH`
environment variable. Both the {file}`bin`
and {file}`sbin` subdirectories of each
package are added.
'';
};
serviceConfig = mkOption {
default = {};
example =
{ RestartSec = 5;
};
type = types.addCheck (types.attrsOf unitOption) checkService;
description = ''
Each attribute in this set specifies an option in the
`[Service]` section of the unit. See
{manpage}`systemd.service(5)` for details.
'';
};
script = mkOption {
type = types.lines;
default = "";
description = "Shell commands executed as the service's main process.";
};
scriptArgs = mkOption {
type = types.str;
default = "";
example = "%i";
description = ''
Arguments passed to the main process script.
Can contain specifiers (`%` placeholders expanded by systemd, see {manpage}`systemd.unit(5)`).
'';
};
preStart = mkOption {
type = types.lines;
default = "";
description = ''
Shell commands executed before the service's main process
is started.
'';
};
postStart = mkOption {
type = types.lines;
default = "";
description = ''
Shell commands executed after the service's main process
is started.
'';
};
reload = mkOption {
type = types.lines;
default = "";
description = ''
Shell commands executed when the service's main process
is reloaded.
'';
};
preStop = mkOption {
type = types.lines;
default = "";
description = ''
Shell commands executed to stop the service.
'';
};
postStop = mkOption {
type = types.lines;
default = "";
description = ''
Shell commands executed after the service's main process
has exited.
'';
};
jobScripts = mkOption {
type = with types; coercedTo path singleton (listOf path);
internal = true;
description = "A list of all job script derivations of this unit.";
default = [];
};
};
config = mkMerge [
(mkIf (config.preStart != "") rec {
jobScripts = makeJobScript "${name}-pre-start" config.preStart;
serviceConfig.ExecStartPre = [ jobScripts ];
})
(mkIf (config.script != "") rec {
jobScripts = makeJobScript "${name}-start" config.script;
serviceConfig.ExecStart = jobScripts + " " + config.scriptArgs;
})
(mkIf (config.postStart != "") rec {
jobScripts = (makeJobScript "${name}-post-start" config.postStart);
serviceConfig.ExecStartPost = [ jobScripts ];
})
(mkIf (config.reload != "") rec {
jobScripts = makeJobScript "${name}-reload" config.reload;
serviceConfig.ExecReload = jobScripts;
})
(mkIf (config.preStop != "") rec {
jobScripts = makeJobScript "${name}-pre-stop" config.preStop;
serviceConfig.ExecStop = jobScripts;
})
(mkIf (config.postStop != "") rec {
jobScripts = makeJobScript "${name}-post-stop" config.postStop;
serviceConfig.ExecStopPost = jobScripts;
})
];
};
stage2ServiceOptions = {
imports = [
stage2CommonUnitOptions
serviceOptions
];
options = {
restartIfChanged = mkOption {
type = types.bool;
default = true;
description = ''
Whether the service should be restarted during a NixOS
configuration switch if its definition has changed.
'';
};
reloadIfChanged = mkOption {
type = types.bool;
default = false;
description = ''
Whether the service should be reloaded during a NixOS
configuration switch if its definition has changed. If
enabled, the value of {option}`restartIfChanged` is
ignored.
This option should not be used anymore in favor of
{option}`reloadTriggers` which allows more granular
control of when a service is reloaded and when a service
is restarted.
'';
};
stopIfChanged = mkOption {
type = types.bool;
default = true;
description = ''
If set, a changed unit is restarted by calling
{command}`systemctl stop` in the old configuration,
then {command}`systemctl start` in the new one.
Otherwise, it is restarted in a single step using
{command}`systemctl restart` in the new configuration.
The latter is less correct because it runs the
`ExecStop` commands from the new
configuration.
'';
};
startAt = mkOption {
type = with types; either str (listOf str);
default = [];
example = "Sun 14:00:00";
description = ''
Automatically start this unit at the given date/time, which
must be in the format described in
{manpage}`systemd.time(7)`. This is equivalent
to adding a corresponding timer unit with
{option}`OnCalendar` set to the value given here.
'';
apply = v: if isList v then v else [ v ];
};
};
};
stage1ServiceOptions = {
imports = [
stage1CommonUnitOptions
serviceOptions
];
};
socketOptions = {
options = {
listenStreams = mkOption {
default = [];
type = types.listOf types.str;
example = [ "0.0.0.0:993" "/run/my-socket" ];
description = ''
For each item in this list, a `ListenStream`
option in the `[Socket]` section will be created.
'';
};
listenDatagrams = mkOption {
default = [];
type = types.listOf types.str;
example = [ "0.0.0.0:993" "/run/my-socket" ];
description = ''
For each item in this list, a `ListenDatagram`
option in the `[Socket]` section will be created.
'';
};
socketConfig = mkOption {
default = {};
example = { ListenStream = "/run/my-socket"; };
type = types.attrsOf unitOption;
description = ''
Each attribute in this set specifies an option in the
`[Socket]` section of the unit. See
{manpage}`systemd.socket(5)` for details.
'';
};
};
};
stage2SocketOptions = {
imports = [
stage2CommonUnitOptions
socketOptions
];
};
stage1SocketOptions = {
imports = [
stage1CommonUnitOptions
socketOptions
];
};
timerOptions = {
options = {
timerConfig = mkOption {
default = {};
example = { OnCalendar = "Sun 14:00:00"; Unit = "foo.service"; };
type = types.attrsOf unitOption;
description = ''
Each attribute in this set specifies an option in the
`[Timer]` section of the unit. See
{manpage}`systemd.timer(5)` and
{manpage}`systemd.time(7)` for details.
'';
};
};
};
stage2TimerOptions = {
imports = [
stage2CommonUnitOptions
timerOptions
];
};
stage1TimerOptions = {
imports = [
stage1CommonUnitOptions
timerOptions
];
};
pathOptions = {
options = {
pathConfig = mkOption {
default = {};
example = { PathChanged = "/some/path"; Unit = "changedpath.service"; };
type = types.attrsOf unitOption;
description = ''
Each attribute in this set specifies an option in the
`[Path]` section of the unit. See
{manpage}`systemd.path(5)` for details.
'';
};
};
};
stage2PathOptions = {
imports = [
stage2CommonUnitOptions
pathOptions
];
};
stage1PathOptions = {
imports = [
stage1CommonUnitOptions
pathOptions
];
};
mountOptions = {
options = {
what = mkOption {
example = "/dev/sda1";
type = types.str;
description = "Absolute path of device node, file or other resource. (Mandatory)";
};
where = mkOption {
example = "/mnt";
type = types.str;
description = ''
Absolute path of a directory of the mount point.
Will be created if it doesn't exist. (Mandatory)
'';
};
type = mkOption {
default = "";
example = "ext4";
type = types.str;
description = "File system type.";
};
options = mkOption {
default = "";
example = "noatime";
type = types.commas;
description = "Options used to mount the file system.";
};
mountConfig = mkOption {
default = {};
example = { DirectoryMode = "0775"; };
type = types.attrsOf unitOption;
description = ''
Each attribute in this set specifies an option in the
`[Mount]` section of the unit. See
{manpage}`systemd.mount(5)` for details.
'';
};
};
};
stage2MountOptions = {
imports = [
stage2CommonUnitOptions
mountOptions
];
};
stage1MountOptions = {
imports = [
stage1CommonUnitOptions
mountOptions
];
};
automountOptions = {
options = {
where = mkOption {
example = "/mnt";
type = types.str;
description = ''
Absolute path of a directory of the mount point.
Will be created if it doesn't exist. (Mandatory)
'';
};
automountConfig = mkOption {
default = {};
example = { DirectoryMode = "0775"; };
type = types.attrsOf unitOption;
description = ''
Each attribute in this set specifies an option in the
`[Automount]` section of the unit. See
{manpage}`systemd.automount(5)` for details.
'';
};
};
};
stage2AutomountOptions = {
imports = [
stage2CommonUnitOptions
automountOptions
];
};
stage1AutomountOptions = {
imports = [
stage1CommonUnitOptions
automountOptions
];
};
sliceOptions = {
options = {
sliceConfig = mkOption {
default = {};
example = { MemoryMax = "2G"; };
type = types.attrsOf unitOption;
description = ''
Each attribute in this set specifies an option in the
`[Slice]` section of the unit. See
{manpage}`systemd.slice(5)` for details.
'';
};
};
};
stage2SliceOptions = {
imports = [
stage2CommonUnitOptions
sliceOptions
];
};
stage1SliceOptions = {
imports = [
stage1CommonUnitOptions
sliceOptions
];
};
}