ansible-systemd-timer

About

This roles enables you to create systemd timers which call scripts or execute commands.

Usage

Define a variable timers. This variable is a dictionary. Every key is a new timer.

Example

Here is an example for my 1337 Telegram Bot. The Timer “calls” a script which sends the message “It’s now 13:37” in one of my Telegram chats every day at 13:37 GMT o’Clock.

timers:
   1337TelegramBot:
      timer_precommand: /bin/bash -c '! /usr/bin/systemctl is-active --quiet other-service.service'
      timer_command: /home/telegrambot/sendMessage.pl
      timer_user: telegrambot
      timer_OnCalendar: "*-*-* 13:37:00 CET"
      timer_AccuracySec: 5s

That’s all the magic.

Existing variables per timer

Variable	Required	Default value / Explanation
timer_precommand	no	Pre-command before command
timer_command	yes	Which command or script to execute
timer_envfile	no	Add environment file
timer_user	no	Under which users the timer_command is executed. Default: root
timer_persistent	no	Takes a boolean argument. If true, the time when the service unit was last triggered is stored on disk. When the timer is activated, the service unit is triggered immediately if it would have been triggered at least once during the time when the timer was inactive. This is useful to catch up on missed runs of the service when the machine was off. Note that this setting only has an effect on timers configured with OnCalendar=. Defaults to false. Source
timer_workingdir	no	Set WorkingDirectory= for the timer
timer_OnActiveSec	no	Relative time after the timer unit was last activated
timer_OnBootSec	no	Relative time after the computer was booted
timer_OnStartupSec	no	Relative time after systemd was started
timer_OnUnitActiveSec	no	Relative time after the service unit was last activated
timer_OnUnitInactiveSec	no	Relative time after the service unit was last deactivated
timer_OnCalendar	no	Absolute time when to call activate the unit
timer_AccuracySec	no	Timer have a default accuracy of round about one minute. You can set the accuracy with this var. Default: 15s

You can chain every timer_On* variable. Example:

timers:
   updateDNS:
      timer_command: /home/dnsupdate/updateMe.pl
      timer_user: dnsupdate
      timer_OnStartupSec: 20s
      timer_OnUnitActiveSec: 5m

The timer unit will be triggered 20 seconds after systemd was started and then every 5 minutes.

More about timers: https://www.freedesktop.org/software/systemd/man/systemd.timer.html

More about timespans: https://www.freedesktop.org/software/systemd/man/systemd.time.html

Existing variables globally, for the role

Variable	Required	Default value / Explanation
systemd_scope	no	Create system or user units. Default: `system`.
systemd_base_path	no	Where to generate the systemd unit files. Set this to e.g. `~/.config/systemd/user` when using systemd_scope=`user`. Default: `/etc/systemd/system`.

You can create user timers for non-root services in combination with become_user: '{{ my_user }}'. Example:

systemd_base_path: ~/.config/systemd/user
systemd_scope: user
timers:
  timer-one:
    timer_command: ...
    timer_OnCalendar: ...
    timer_user: '{{ my_user }}'
  ...

Working with shell redirection

Shell redirection does not work out of the box. You have to work around that by calling sh or bash.
This won’t work: echo hello > /var/log/hello.log
This will work: /usr/bin/bash -c \"echo hello > /var/log/hello.log\"

Tip: Always use full paths. To see where sh or bash is stored on your system you have to use which:

[root@pizza ~]# which bash
/usr/bin/bash