And let's make use of it to implement two new unit settings with it:
1. LogLevelMax= is a new per-unit setting that may be used to configure
log priority filtering: set it to LogLevelMax=notice and only
messages of level "notice" and lower (i.e. more important) will be
processed, all others are dropped.
2. LogExtraFields= is a new per-unit setting for configuring per-unit
journal fields, that are implicitly included in every log record
generated by the unit's processes. It takes field/value pairs in the
form of FOO=BAR.
Also, related to this, one exisiting unit setting is ported to this new
facility:
3. The invocation ID is now pulled from /run/systemd/units/ instead of
cgroupfs xattrs. This substantially relaxes requirements of systemd
on the kernel version and the privileges it runs with (specifically,
cgroupfs xattrs are not available in containers, since they are
stored in kernel memory, and hence are unsafe to permit to lesser
privileged code).
/run/systemd/units/ is a new directory, which contains a number of files
and symlinks encoding the above information. PID 1 creates and manages
these files, and journald reads them from there.
Note that this is supposed to be a direct path between PID 1 and the
journal only, due to the special runtime environment the journal runs
in. Normally, today we shouldn't introduce new interfaces that (mis-)use
a file system as IPC framework, and instead just an IPC system, but this
is very hard to do between the journal and PID 1, as long as the IPC
system is a subject PID 1 manages, and itself a client to the journal.
This patch cleans up a couple of types used in journal code:
specifically we switch to size_t for a couple of memory-sizing values,
as size_t is the right choice for everything that is memory.
Fixes: #4089Fixes: #3041Fixes: #4441
Cache client metadata, in order to be improve runtime behaviour under
pressure.
This is inspired by @vcaputo's work, specifically:
https://github.com/systemd/systemd/pull/2280
That code implements related but different semantics.
For a longer explanation what this change implements please have a look
at the long source comment this patch adds to journald-context.c.
After this commit:
# time bash -c 'dd bs=$((1024*1024)) count=$((1*1024)) if=/dev/urandom | systemd-cat'
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 11.2783 s, 95.2 MB/s
real 0m11.283s
user 0m0.007s
sys 0m6.216s
Before this commit:
# time bash -c 'dd bs=$((1024*1024)) count=$((1*1024)) if=/dev/urandom | systemd-cat'
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 52.0788 s, 20.6 MB/s
real 0m52.099s
user 0m0.014s
sys 0m7.170s
As side effect, this corrects the journal's rate limiter feature: we now
always use the unit name as key for the ratelimiter.
