[systemd-devel] [RFC] runtime configurable timer

[Zbigniew Jędrzejewski-Szmek]

On Wed, Sep 17, 2014 at 04:20:14PM +0900, WaLyong Cho wrote:
> Before start working it, we need some of discussion about how make the
> transient unit. I think we have two options.
> One is, as you said, make systemd-at and the other is add option to
> systemd-run. (e.g. --OnCalendar=, --OnActiveSec= or so)
> If we choose the former, then we should consider how load the relate
> unit(service). Because, the timer unit is not working alone. It related
> with service unit. So, if the transient timer unit related with already
> existing service then it will not much complicate. But if we want to add
> both transient timer and transient service then it will more complicate.
> In latter case, I think, it is more easier. Because, we can get a all of
> information to make two transient service transient timer.
Agreed, doing it all from a single systemd-run invocation seems the way
to go. It should be both easier to implement and also nicer to use. 

> But
> internally we should call StartTransientUnit method call to start the
> timer unit and AddTransientUnit(or LoadTransientUnit(?)) to add service
> unit what will be started by the timer unit.
Something like that... but there are some corner cases. StartTransientUnit
is fairly limited now in what can be set, and I think behaviour should be
retained when the unit is started by transient timers. So maybe the best
option is simply to extend StartTransientUnit (add a new call
StartTransientUnitDelayed or something like that) with a parameter
for timer specification. Then have systemd internally created both the
transient service unit and a transient timer unit.

Zbyszek