Services which are not crucial to system bootup, and have Type=oneshot
can effectively "hang" the system if they fail to complete for whatever
reason. To allow the boot to continue, kill them after a timeout.
In case of systemd-journal-flush the flush will continue in the background,
and in the other two cases the job will be aborted, but this should not
result in any permanent problem.
Otherwise we could attempt to flush the journal while /var/log/ was
still ro, and silently skip journal flushing.
The way that errors in flushing are handled should still be changed to
be more transparent and robust.
This new command will ask the journal daemon to flush all log data
stored in /run to /var, and wait for it to complete. This is useful, so
that in case of Storage=persistent we can order systemd-tmpfiles-setup
afterwards, to ensure any possibly newly created directory in /var/log
gets proper access mode and owners.
The old automatism that the flushing of the journal from /run to /var
was triggered by the appearance of /var/log/journal is broken if that
directory is mounted from another host and hence always available to be
useful as mount point. To avoid probelsm with this, introduce a new unit
that is explicitly orderer after all mounte files systems and triggers
the flushing.
Zbigniew Jędrzejewski-Szmek