nixpkgs/modules/system/boot/systemd-unit-options.nix
Eelco Dolstra 96ba0ca283 For some units, use "systemctl restart" rather than "systemctl stop/start"
During a configuration switch, changed units are stopped in the old
configuration, then started in the new configuration (i.e. after
running the activation script and running "systemctl daemon-reload").
This ensures that services are stopped using the ExecStop/ExecStopPost
commands from the old configuration.

However, for some services it's undesirable to stop them; in
particular dhcpcd, which deconfigures its network interfaces when it
stops.  This is dangerous when doing remote upgrades - usually things
go right (especially because the switch script ignores SIGHUP), but
not always (see 9aa69885f0).  Likewise,
sshd should be kept running for as long as possible to prevent a
lock-out if the switch fails.

So the new option ‘stopIfChanged = false’ causes "systemctl restart"
to be used instead of "systemctl stop" followed by "systemctl start".
This is only proper for services that don't have stop commands.  (And
it might not handle dependencies properly in some cases, but I'm not
sure.)
2013-01-05 01:05:25 +01:00

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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.
'';
};
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 services'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.
'';
};
script = mkOption {
type = types.uniq types.string;
default = "";
description = "Shell commands executed as the service's main process.";
};
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 // {
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.
'';
};
};
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.
'';
};
};
}