GSoC : Creating timers in Cockpit
In this blog, I will provide a description of how to create a (systemd) timer using Cockpit. Also I will mention about the proposed feature sets and what actually got merged in Cockpit.
How to create timers
- Repeat hourly timers
Hourly timers are used for repeating events on the mentioned minutes every hour.
Here we set up a timer that repeats at 5 min and 26 min past every hour.
This command creates a tmp/date file that contains the time when this timer runs.
The contents of hourly_timer.service file and hourly_timer.timer file are given below:
[Unit]
Description=Hourly timer
[Service]
ExecStart=/bin/sh -c '/bin/date >> /tmp/date'
[Install]
WantedBy=default.target[Unit]
Description=Hourly timer
[Timer]
OnCalendar=*-*-* *:5,26:00
2. Repeat daily timers
Daily timers are used to repeat events on the mentioned hours and minutes every day. Here we create a daily timer that repeats every day at 1:20, 2:40, 21:16. The daily_timer.service and daily_timer.timer file’s contents are as follows
[Unit]
Description=Daily Timer
[Service]
ExecStart=/bin/sh -c '/bin/date >> /tmp/date'
[Install]
WantedBy=default.target[Unit]
Description=Daily Timer
[Timer]
OnCalendar=*-*-* 1:20:00
OnCalendar=*-*-* 2:40:00
OnCalendar=*-*-* 21:16:00
3. Repeat weekly timers
Weekly timers are used to repeat events on the mentioned week-days every week. Here we create a weekly timer that repeats every week on Monday at 10:1, Thursday at 12:00, Friday at 01:10.
Contents of weekly.service[Unit]
Description=Weekly Timer
[Service]
ExecStart=/bin/sh -c '/bin/date >> /tmp/date'
[Install]
WantedBy=default.targetContents of weekly.timer[Unit]
Description=Weekly Timer
[Timer]
OnCalendar=Mon *-*-* 10:1:00
OnCalendar=Thu *-*-* 12:0:00
OnCalendar=Fri *-*-* 1:10:00
Repeat monthly timer
Monthly timers are used for repeat events on mentioned dates every month.
This timer runs on 21st and 24th of every month at 2 AM and 4 AM respectively. The contents of monthly.service and monthly.timer are
[Unit]
Description=Monthly
[Service]
ExecStart=/bin/sh -c '/bin/date >> /tmp/date'
[Install]
WantedBy=default.target[Unit]
Description=Monthly
[Timer]
OnCalendar=*-*-21 2:0:00
OnCalendar=*-*-24 4:0:00
Repeat yearly timer
Yearly timer repeats events on the specific days in every year. The contents of the yearly_timer.service and yearly_timer.timer are :
[Unit]
Description=Yearly Timer
[Service]
ExecStart=/bin/sh -c 'while true; do sleep 5; done'
[Install]
WantedBy=default.target[Unit]
Description=Yearly Timer
[Timer]
OnCalendar=*-08-15 15:0:00
OnCalendar=*-09-06 1:22:00
Boot timer
A boot timer is setup which starts 2 seconds after boot. The contents of boot.service and boot.timer are as follows:
[Unit]
Description=Boot Timer
[Service]
ExecStart=/usr/bin/sh -c 'echo hello >> /tmp/hello'
[Install]
WantedBy=default.target[Unit]
Description=Boot Timer
[Timer]
OnBootSec=2sec
Display of timers
The timer page in Cockpit displays the next run and last run time of the timers.
Proposed feature’s as part of GSoC were:
➔ A working systemd timer interface to schedule unit services in Cockpit web interface.
➔ Addition and modification of the timer properties to create, modify and schedule tasks.
➔ Implement a timer interface as described in https://trello.com/c/1B2lZViZ/74-timers-and-cron.
Proposed features that got merged as part of Cockpit includes:
- Creation of calendar and monotonic timers without using D-BUS.
- Display of next run and last run time of existing timers like in the mock-up.
Extra features that could be added include :
- Modification and deletion of timers.
- Creation of timers for already existing services.
