After soft-reboot, /var/log/journal may be initially read-only,
and becomes writable a bit later. In such case, runtime journal is
initially opened by journald. Hence, we need to flush to /var when it is
ready.
No functional change, just a cleanup to make the subsequent changes easier to
see. This is a continuation of 9810e41942
> The block is reordered and split to have:
> 1. description + documentation
> 2. (optionally) conditions
> 3. all the dependencies
The dependencies for shutdown.target are listed separately because they are the
other deps are for startup, and shutdown.target only matter much later.
This is a follow-up for d5ee050ffc, and
reintroduces a requirement dep from systemd-journal-flush.service onto
systemd-journald.service, but a weaker one than originally: a Wants= one
instead of a Requires= one.
Why? Simply because the service issues an IPC call to the journald,
hence it should pull it in. (Note that socket activation doesn't happen
for the Varlink socket it uses, hence we should pull in the service
itself.)
Due to the fact that systemd-journal-flush.service has
"Requires=systemd-journald.service", this service is stopped too when journald
is requested to do so.
However stopping systemd-journal-flush.service implies that journald
relinquishes /var hence implicitly switching back to the volatile storage
mode and removing /run/systemd/journal/flushed.
If journald is started afterwards, it will run in volatile storage mode
regardless of the value of 'Storage=' as it believes now that /var is not yet
ready (because the flushed flag is missing).
Because this flag is mainly an indication for journald that the initialization
of /var/log/journal (during the boot process) has been done,
systemd-journal-flush.service shouldn't be tied to the state of journald itself
but to the state of /var/log/journal, hence to the state of the system.
I'm working on building initramfs images directly from normal packages, and it
doesn't make sense for those units to be started. Pristine system rpms need to
behave correctly as much as possible also in the initrd, and those units are
enabled by the rpms. There usually isn't enough time for the timer to actually
fire, but starting it gives a line on the console and generally looks confusing
and sloppy. Flushing the journal means that its actually lost, since the real
/var is not available yet.
Another approach would be not enable those units, but right now they are
statically enabled, and changing that would be more work, and doesn't really
seem necessary, since the condition checks are very quick.
Checking for /etc/initrd-release is the standard condition that the initrd
units use, so let's do the same here.
This makes things a bit simpler and the build a bit faster, because we don't
have to rewrite files to do the trivial substitution. @rootbindir@ is always in
our internal $PATH that we use for non-absolute paths, so there should be no
functional change.
