[systemd-devel] No error even a Required= service does not exist

[Zbigniew Jędrzejewski-Szmek]

On Mon, Nov 25, 2019 at 06:13:17PM +0200, Uoti Urpala wrote:
> On Mon, 2019-11-25 at 15:19 +0200, Mantas Mikulėnas wrote:
> > > Requires=xyz.service 
> > > 
> > > produces no complaint and starts the service even if there is no xyz.service
> > > Is this the normal behavior or can I configure systemd to throw an error in this case?
> > 
> > The docs say you can get this behavior if you also have After=xyz.service. (Not entirely sure why.)
> 
> No when there IS NOT an "After=xyz.service".
> 
> Without "After=", there is no ordering dependency - it just tells that
> anything starting this unit will effectively order the start of the
> other as well. Without ordering, this unit can be the one to start
> first. If the other one fails to actually start later, that doesn't
> make systemd go back to stop this one (note that this is consistent
> with ordering dependencies - if a depended-on service fails later
> during runtime, that does not automatically force a stop of already
> running depending services). I guess this logic extends to failures of
> the "does not exist at all" type where there was never a chance of
> successfully starting the unit.

Sounds like a bug. I'd expect the transaction to fail if the Required
unit cannot be found.

Zbyszek