Timer guidelines
Main page
Add in 'Cron Files' section:
This would go on the cron-specific page as well.
Additions/rework of systemd guildelines:
Systemd guidelines
For https://fedoraproject.org/wiki/Packaging:Systemd:
Systemd allows for multiple forms of activated services. This document discusses #Hardware activation, #Socket activation, and #DBus activation, and #Timer activation.
...
Timer activation
Timer activation is used for tasks that run at a specified calendar time, a
specified repeating interval, or at a specifed interval relative to system
boot or other actions. A timer unit file ends in .timer, and contains a
[Timer]
section that describes when the timer unit performs an action.
A timer unit does not itself run a command. Instead it starts a service unit when it
triggers. By default, it starts a service unit of the same name.
[Install]
section for timer units
A timer unit that is tied to a specific service and should only run if that service is enabled running should include:
[Install] WantedBy=<dependent service>.service
If it also should only run if that service is running, it should include:
[Unit] BindsTo=<dependent service>.service
On the other hand, a timer unit that is independent of other services should include:
[Install] WantedBy=timers.target
Examples
Bound to another service
A periodic service to be run while a service is running consists of three units - the main service unit, the timer unit, and a service unit for the scheduled task.
acme.service
:
[Unit] Description=ACME Sample Service Documentation=man:acme(1) [Service] ExecStart=/usr/bin/acmed [Install] WantedBy=multi-user.target
acme-job.timer
:
[Unit] Description=ACME Sample Timer Trigger Documentation=man:acme(1) BindTo=acme.service [Timer] OnCalendar=daily [Install] WantedBy=acme.service
acme-job.service
:
[Unit] Description=ACME post-boot service Documentation=man:acme(1) [Service] User=acme ExecStart=/usr/bin/acme-job
After Boot Time Trigger
A one-shot timer that runs after boot. Not tied to any service.
acme-job.timer
:
[Unit] Description=ACME Sample Timer Trigger 5 Minutes After Boot Documentation=man:acme(1) [Timer] OnBootSec=5m [Install] WantedBy=timers.target
acme-job.service
:
[Unit] Description=ACME post-boot service Documentation=man:acme(1) [Service] User=acme ExecStart=/usr/bin/acme-job
Post-boot and Hourly timer
Differnt methods of scheduling the timer can be combined with the use of multiple directives under [Timer].
acme.service
:
[Unit] Description=ACME Sample Service Documentation=man:acme(1) [Service] ExecStart=/usr/bin/acmed [Install] WantedBy=multi-user.target
acme-job.timer
:
[Unit] Description=ACME Sample Timer Trigger 5 Minutes After Boot And Hourly After That Documentation=man:acme(1) BindTo=acme.service [Timer] OnBootSec=5m OnUnitActiveSec=1h [Install] WantedBy=timers.target
acme-job.service
::
[Unit] Description=Daily ACME Job Documentation=man:acme(1) [Service] User=acme ExecStart=/usr/bin/acme-job
Traditional Hourly/Daily/etc timer
A timer that runs on an interval, much like a 'normal' cron task.
acme.timer
[Unit] Description=ACME Sample Timer Unit Documentation=man:acme(1) [Timer] OnCalendar=daily|hourly|monthly [Install] WantedBy=timers.target
acme.service
[Unit] Description=Periodic ACME task Documentation=man:acme(1) [Service] User=acme ExecStart=/usr/bin/acme