[systemd-devel] Starting a service on shutdown

[David Strauss]

If unmounting happens, deterministically, before shutdown, why not
make your service WantedBy=umount.target (maybe still with
DefaultDependencies=no)?

On Mon, Jan 21, 2013 at 4:38 AM, Umut Tezduyar <umut at tezduyar.com> wrote:
> Hi
>
> How do I start a service on shutdown that will start and finish before any
> of the mount points being unmounted?
>
> As it is explained here
> (http://lists.freedesktop.org/archives/systemd-devel/2012-November/007558.html)
> the shutdown order is the reverse of startup order though it is not clear
> what is happening when a service that is not in the startup sequence is
> being started. Following is a sample unit file I have been working on.
>
> [Unit]
> Description=Taking Long Time
> DefaultDependencies=no
> Before=shutdown.target
>
> [Service]
> Type=oneshot
> ExecStart=/bin/sleep 60
>
> [Install]
> WantedBy=shutdown.target
>
> Before=shutdown.target ensures that shutdown.target is not reached before
> the service is finished since it's type is "oneshot". But if I add
> "Before=umount.target" or "Before=basic.target" to the service file, the
> requested shutdown order is not obeyed.
>
> Output snipped:
>
> [OK] Stopped target Local File Systems
>      Unmounting /usr/local...
>      Unmounting /lib/persistent...
>      Starting Taking Long Time
> [OK] Unmounted /usr/local
> [OK] Unmounted /lib/persistent
>
> What am I trying to achieve:
>
> I would like to start a service on shutdown/restart. This service accesses
> (read/write) to the file systems and for that reason I don't want any of the
> file systems unmounted by systemd before the service completes.
>
> Thank you,
> Umut
>
>
>
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David Strauss
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