nixpkgs/modules/system/boot/systemd-unit-options.nix
Eelco Dolstra f19065c283 Fix broken systemd shutdown services
The services systemd-random-seed-save.service and
systemd-update-utmp-shutdown.service from systemd 203 don't work,
because they have a RequiresMountFor dependency on /var/lib and
/var/log.  Such a dependency produces a cycle, causing systemd to drop
those services:

  Fixing conflicting jobs by deleting job poweroff.target/stop
  Deleting job systemd-poweroff.service/stop as dependency of job poweroff.target/stop
  Deleting job umount.target/stop as dependency of job systemd-poweroff.service/stop
  Deleting job -.mount/start as dependency of job umount.target/stop
  Deleting job systemd-random-seed-save.service/start as dependency of job -.mount/start
  Deleting job systemd-update-utmp-shutdown.service/start as dependency of job -.mount/start

Dropping the RequiresMountFor doesn't work either, because then
/var/... may have meen unmounted or remounted read-only.

Upstream systemd fixes this by doing the actual work from an ExecStop
action in an already-running service than conflicts with
shutdown.target.  So I backported that here.  The main consequence is
that wtmp shutdown records now get written properly.

The main lesson: shutdown.target is useless for pulling in services
during shutdown if they need to write anywhere.
2013-09-22 21:39:05 +02:00

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{ config, pkgs }:
with pkgs.lib;
rec {
unitOptions = {
enable = mkOption {
default = true;
types = 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. <literal>serial-getty@ttyS0</literal>)
from being started.
'';
};
description = mkOption {
default = "";
types = types.uniq types.string;
description = "Description of this unit used in systemd messages and progress indicators.";
};
requires = mkOption {
default = [];
types = types.listOf types.string;
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 = [];
types = types.listOf types.string;
description = ''
Start the specified units when this unit is started.
'';
};
after = mkOption {
default = [];
types = types.listOf types.string;
description = ''
If the specified units are started at the same time as
this unit, delay this unit until they have started.
'';
};
before = mkOption {
default = [];
types = types.listOf types.string;
description = ''
If the specified units are started at the same time as
this unit, delay them until this unit has started.
'';
};
bindsTo = mkOption {
default = [];
types = types.listOf types.string;
description = ''
Like requires, but in addition, if the specified units
unexpectedly disappear, this unit will be stopped as well.
'';
};
partOf = mkOption {
default = [];
types = types.listOf types.string;
description = ''
If the specified units are stopped or restarted, then this
unit is stopped or restarted as well.
'';
};
conflicts = mkOption {
default = [];
types = types.listOf types.string;
description = ''
If the specified units are started, then this unit is stopped
and vice versa.
'';
};
requiredBy = mkOption {
default = [];
types = types.listOf types.string;
description = "Units that require (i.e. depend on and need to go down with) this unit.";
};
wantedBy = mkOption {
default = [];
types = types.listOf types.string;
description = "Units that want (i.e. depend on) this unit.";
};
unitConfig = mkOption {
default = {};
example = { RequiresMountsFor = "/data"; };
type = types.attrs;
description = ''
Each attribute in this set specifies an option in the
<literal>[Unit]</literal> section of the unit. See
<citerefentry><refentrytitle>systemd.unit</refentrytitle>
<manvolnum>5</manvolnum></citerefentry> for details.
'';
};
restartTriggers = mkOption {
default = [];
description = ''
An arbitrary list of items such as derivations. If any item
in the list changes between reconfigurations, the service will
be restarted.
'';
};
};
serviceOptions = unitOptions // {
environment = mkOption {
default = {};
type = types.attrs;
example = { PATH = "/foo/bar/bin"; LANG = "nl_NL.UTF-8"; };
description = "Environment variables passed to the service's processes.";
};
path = mkOption {
default = [];
apply = ps: "${makeSearchPath "bin" ps}:${makeSearchPath "sbin" ps}";
description = ''
Packages added to the service's <envar>PATH</envar>
environment variable. Both the <filename>bin</filename>
and <filename>sbin</filename> subdirectories of each
package are added.
'';
};
serviceConfig = mkOption {
default = {};
example =
{ StartLimitInterval = 10;
RestartSec = 5;
};
type = types.attrs;
description = ''
Each attribute in this set specifies an option in the
<literal>[Service]</literal> section of the unit. See
<citerefentry><refentrytitle>systemd.service</refentrytitle>
<manvolnum>5</manvolnum></citerefentry> for details.
'';
check = v:
let assertValueOneOf = name: values: attr:
let val = getAttr name attr;
in optional ( hasAttr name attr && !elem val values) "${name} ${val} not known to systemd";
checkType = assertValueOneOf "Type" ["simple" "forking" "oneshot" "dbus" "notify" "idle"];
checkRestart = assertValueOneOf "Restart" ["no" "on-success" "on-failure" "on-abort" "always"];
errors = concatMap (c: c v) [checkType checkRestart];
in if errors == [] then true
else builtins.trace (concatStringsSep "\n" errors) false;
};
script = mkOption {
type = types.uniq types.string;
default = "";
description = "Shell commands executed as the service's main process.";
};
scriptArgs = mkOption {
type = types.uniq types.string;
default = "";
description = "Arguments passed to the main process script.";
};
preStart = mkOption {
type = types.string;
default = "";
description = ''
Shell commands executed before the service's main process
is started.
'';
};
postStart = mkOption {
type = types.string;
default = "";
description = ''
Shell commands executed after the service's main process
is started.
'';
};
postStop = mkOption {
type = types.string;
default = "";
description = ''
Shell commands executed after the service's main process
has exited.
'';
};
restartIfChanged = mkOption {
type = types.bool;
default = true;
description = ''
Whether the service should be restarted during a NixOS
configuration switch if its definition has changed.
'';
};
stopIfChanged = mkOption {
type = types.bool;
default = true;
description = ''
If set, a changed unit is restarted by calling
<command>systemctl stop</command> in the old configuration,
then <command>systemctl start</command> in the new one.
Otherwise, it is restarted in a single step using
<command>systemctl restart</command> in the new configuration.
The latter is less correct because it runs the
<literal>ExecStop</literal> commands from the new
configuration.
'';
};
};
socketOptions = unitOptions // {
listenStreams = mkOption {
default = [];
types = types.listOf types.string;
example = [ "0.0.0.0:993" "/run/my-socket" ];
description = ''
For each item in this list, a <literal>ListenStream</literal>
option in the <literal>[Socket]</literal> section will be created.
'';
};
socketConfig = mkOption {
default = {};
example = { ListenStream = "/run/my-socket"; };
type = types.attrs;
description = ''
Each attribute in this set specifies an option in the
<literal>[Socket]</literal> section of the unit. See
<citerefentry><refentrytitle>systemd.socket</refentrytitle>
<manvolnum>5</manvolnum></citerefentry> for details.
'';
};
};
timerOptions = unitOptions // {
timerConfig = mkOption {
default = {};
example = { OnCalendar = "Sun 14:00:00"; Unit = "foo.service"; };
type = types.attrs;
description = ''
Each attribute in this set specifies an option in the
<literal>[Timer]</literal> section of the unit. See
<citerefentry><refentrytitle>systemd.timer</refentrytitle>
<manvolnum>5</manvolnum></citerefentry> and
<citerefentry><refentrytitle>systemd.time</refentrytitle>
<manvolnum>5</manvolnum></citerefentry> for details.
'';
};
};
mountOptions = unitOptions // {
what = mkOption {
example = "/dev/sda1";
type = types.uniq types.string;
description = "Absolute path of device node, file or other resource. (Mandatory)";
};
where = mkOption {
example = "/mnt";
type = types.uniq types.string;
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.uniq types.string;
description = "File system type.";
};
options = mkOption {
default = "";
example = "noatime";
type = types.string;
merge = concatStringsSep ",";
description = "Options used to mount the file system.";
};
mountConfig = mkOption {
default = {};
example = { DirectoryMode = "0775"; };
type = types.attrs;
description = ''
Each attribute in this set specifies an option in the
<literal>[Mount]</literal> section of the unit. See
<citerefentry><refentrytitle>systemd.mount</refentrytitle>
<manvolnum>5</manvolnum></citerefentry> for details.
'';
};
};
}