From the syslog.socket unit file of newer systemd versions:
The default syslog implementation should make syslog.service a
symlink to itself, so that this socket activates the right actual
syslog service.
Examples:
/etc/systemd/system/syslog.service ->
/lib/systemd/system/rsyslog.service
/etc/systemd/system/syslog.service ->
/lib/systemd/system/syslog-ng.service
Best way to achieve that is by adding this to your unit file
(i.e. to rsyslog.service or syslog-ng.service):
[Install]
Alias=syslog.service
http://cgit.freedesktop.org/systemd/systemd/tree/units/syslog.socket#n26
This allows systemd upstream to set stdout/stderr of all spawned
services by default to 'syslog'. In order to avoid log loops rsyslog
itself must be have its stdout/stderr connected to 'null' in that case,
however.
rsyslog doesn't actually do a configuration reload on SIGHUP, hence
let's not pretend it does and drop the ExecReload= line, so that the
clients will rather restart than reload the service.
In systemd we now have a standard socket unit for /dev/log called
syslog.socket. This unit can be shared between an early boot mini syslog
and the full syslog implementation started later on. The mini syslog is
shipped along systemd and does nothing but simply forward the data
received through /dev/log to the kernel log buffer (i.e. kmsg, as
visible by dmesg). It is run during early boot, and then as soon as
rsyslog starts up it is terminated, so that rsyslog can take over the
/dev/log socket. Since one of the first things rsyslog does after
starting up is flushing the kernel log buffer to disk we end up with all
data from early boot up in syslog.
This patch changes two things: removes rsyslog.socket and instead
configures rsyslog.service to take possession of syslock.socket. And
secondly includes a PreStart line to terminate the running syslog bridge
instance.
This adds a systemd socket and service unit file to the default install
if systemd is found or explicitly enabled in ./configure.
Patch is against current git v5-devel.
