NAME
systemd.scope - Scope unit configurationSYNOPSIS
scope.scopeDESCRIPTION
Scope units are not configured via unit configuration files, but are only created programmatically using the bus interfaces of systemd. They are named similar to filenames. A unit whose name ends in ".scope" refers to a scope unit. Scopes units manage a set of system processes. Unlike service units, scope units manage externally created processes, and do not fork off processes on its own. The main purpose of scope units is grouping worker processes of a system service for organization and for managing resources. systemd-run --scope may be used to easily launch a command in a new scope unit from the command line. See the New Control Group Interfaces[1] for an introduction on how to make use of scope units from programs. Note that, unlike service units, scope units have no "main" process: all processes in the scope are equivalent. The lifecycle of the scope unit is thus not bound to the lifetime of one specific process, but to the existence of at least one process in the scope. This also means that the exit statuses of these processes are not relevant for the scope unit failure state. Scope units may still enter a failure state, for example due to resource exhaustion or stop timeouts being reached, but not due to programs inside of them terminating uncleanly. Since processes managed as scope units generally remain children of the original process that forked them off, it is also the job of that process to collect their exit statuses and act on them as needed.AUTOMATIC DEPENDENCIES
Implicit Dependencies
Implicit dependencies may be added as result of resource control parameters as documented in systemd.resource-control(5).Default Dependencies
The following dependencies are added unless DefaultDependencies=no is set:•Scope units will automatically have
dependencies of type Conflicts= and Before= on shutdown.target.
These ensure that scope units are removed prior to system shutdown. Only scope
units involved with early boot or late system shutdown should disable
DefaultDependencies= option.
OPTIONS
Scope files may include a [Unit] section, which is described in systemd.unit(5). Scope files may include a [Scope] section, which carries information about the scope and the units it contains. A number of options that may be used in this section are shared with other unit types. These options are documented in systemd.kill(5) and systemd.resource-control(5). The options specific to the [Scope] section of scope units are the following: OOMPolicy=Configure the out-of-memory (OOM) kernel
killer policy. Note that the userspace OOM killer
systemd-oomd.service(8) is a more flexible solution that aims to
prevent out-of-memory situations for the userspace, not just the kernel.
On Linux, when memory becomes scarce to the point that the kernel has trouble
allocating memory for itself, it might decide to kill a running process in
order to free up memory and reduce memory pressure. This setting takes one of
continue, stop or kill. If set to continue and a
process of the service is killed by the OOM killer, this is logged but the
unit continues running. If set to stop the event is logged but the unit
is terminated cleanly by the service manager. If set to kill and one of
the unit's processes is killed by the OOM killer the kernel is instructed to
kill all remaining processes of the unit too, by setting the memory.oom.group
attribute to 1; also see kernel documentation[2].
Defaults to the setting DefaultOOMPolicy= in
systemd-system.conf(5) is set to, except for units where
Delegate= is turned on, where it defaults to continue.
Use the OOMScoreAdjust= setting to configure whether processes of the
unit shall be considered preferred or less preferred candidates for process
termination by the Linux OOM killer logic. See systemd.exec(5) for
details.
This setting also applies to systemd-oomd. Similarly to the kernel OOM
kills, this setting determines the state of the unit after systemd-oomd
kills a cgroup associated with it.
RuntimeMaxSec=
Configures a maximum time for the scope to
run. If this is used and the scope has been active for longer than the
specified time it is terminated and put into a failure state. Pass
"infinity" (the default) to configure no runtime limit.
RuntimeRandomizedExtraSec=
This option modifies RuntimeMaxSec= by
increasing the maximum runtime by an evenly distributed duration between 0 and
the specified value (in seconds). If RuntimeMaxSec= is unspecified,
then this feature will be disabled.
Check systemd.unit(5), systemd.exec(5), and systemd.kill(5)
for more settings.
SEE ALSO
systemd(1), systemd-run(1), systemd.unit(5), systemd.resource-control(5), systemd.service(5), systemd.directives(7).NOTES
- 1.
- New Control Group Interfaces
- 2.
- kernel documentation
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