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

[Mikko.Rapeli at bmw.de]

Hi,

On Mon, Nov 25, 2019 at 02:07:23PM +0100, Jörg Weinhardt wrote:
> Hi,
> 
> the behavior of systemd is not quite clear to me:
> I have a service which requires another service to be started and running,
> so I use a Requires= dependency to the required service.
> But if the required service does not exist at all, there is no error message from systemd.
> e.g. 
> 
> 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?
> 
> If I write
> "Requires=xyz"
> 
> there will be a message: Failed to add dependency on xyz, ignoring: Invalid argument
> Does that error mean that "xyz" is not a valid unit name?

I guess all these are by design. Maybe you need Wants instead of Requires in the service file.
See:

https://www.freedesktop.org/software/systemd/man/systemd.unit.html#Requires=
and
https://www.freedesktop.org/software/systemd/man/systemd.unit.html#Wants=
and possibly even
https://www.freedesktop.org/software/systemd/man/systemd.unit.html#Before=

Cheers,

-Mikko

> 
> Thank you,
> Joerg
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