[systemd-devel] does "Before=network.target" really work

[Xin Long]

On Fri, Jun 24, 2016 at 6:22 PM, Michael Hirmke <mh at mike.franken.de> wrote:
> Hi Xin,
>
>>Hi,
>
>>I have a service, and want it to be stopped only after network is
>>stopped when system shutdown.
>
>>I checked "man systemd.special ", network is a special internal
>>service for systemd, , and I found "network.target":
>>"at shutdown, a unit that is ordered after network.target will be
>>stopped before the network -- to whatever  level it might be set up
>>then -- is shut down".
>>That means "After=network.target" can work well.
>
>>But my situation is opposite to that, I need "a unit that is ordered
>>before network.target will be stopped *after* the network so
>>shutdown".
>
>>So I added "Before=network.target" to .service file. can it really
>>work as I expect?
>
> it depends on what you're trying to do with this information.
> AFAIK network.target is related to the network stack as such. It does
> not apply to a certain interface is up, down, activated or deactivated.
> If you need the information for the network stack being up or down,
> the use of network.target is ok - and works for me.
>
my case only cares about shutdown time.
I do not know "Before=network.target" can make my service stop
after which phase of network is stopped.
and I also cannot find anything in man doc.

but I can find some services are truly using it now:
$ grep "Before=network.target" . -R
./wpa_supplicant.service:Before=network.target
./NetworkManager.service:Before=network.target
./NetworkManager-wait-online.service:Before=network.target network-online.target
./arp-ethers.service:Before=network.target
./firewalld.service:Before=network.target

what I need is just make sure my service will stop after we just can't
communicate with other host. (no need to after device down, or stack
is removed)