[systemd-devel] understanding systemd ordering vs dependencies

[Zbigniew Jędrzejewski-Szmek]

On Mon, Jul 25, 2016 at 10:59:00PM +0000, Patrick Schleizer wrote:
> Hi!
> 
> I am trying to understand systemd ordering vs dependencies.
> 
> When I am already using Wants=, why should I also add After=?
> 
> When I am already using After=, why should I also add Wants=?

Please see the description of Requires
(https://www.freedesktop.org/software/systemd/man/systemd.unit.html#Requires=)
It explains the relationship between Requires/Wants and After.

> Systemd ordering with Before= and After= is more about speed concerns?
No.

> Such as for example to express "i want the webserver running before the
> backup service" so I added for my custom backup systemd service
> After=apache2.service."
No really.

> Systemd ordering with Before= and After= is not "as strictly" adhered
> compared to Wants= and WantedBy=?
No.

> Before, I thought After= is effectively as good as Wants=, but this is
> apparently wrong?
Yes.

Zbyszek