JOURNALD.CONF(5) journald.conf JOURNALD.CONF(5)
NAME
journald.conf, journald.conf.d, journald@.conf - Journal service
configuration files
SYNOPSIS
/etc/systemd/journald.conf
/etc/systemd/journald.conf.d/*.conf
/run/systemd/journald.conf.d/*.conf
/usr/lib/systemd/journald.conf.d/*.conf
/etc/systemd/journald@NAMESPACE.conf
/etc/systemd/journald@NAMESPACE.conf.d/*.conf
/run/systemd/journald@NAMESPACE.conf.d/*.conf
/usr/lib/systemd/journald@NAMESPACE.conf.d/*.conf
DESCRIPTION
These files configure various parameters of the systemd journal
service, systemd-journald.service(8). See systemd.syntax(7) for a
general description of the syntax.
The systemd-journald instance managing the default namespace is
configured by /etc/systemd/journald.conf and associated drop-ins.
Instances managing other namespaces read
/etc/systemd/journald@NAMESPACE.conf and associated drop-ins with the
namespace identifier filled in. This allows each namespace to carry a
distinct configuration. See systemd-journald.service(8) for details
about journal namespaces.
CONFIGURATION DIRECTORIES AND PRECEDENCE
The default configuration is set during compilation, so configuration
is only needed when it is necessary to deviate from those defaults.
Initially, the main configuration file in /etc/systemd/ contains
commented out entries showing the defaults as a guide to the
administrator. Local overrides can be created by editing this file or
by creating drop-ins, as described below. Using drop-ins for local
configuration is recommended over modifications to the main
configuration file.
In addition to the "main" configuration file, drop-in configuration
snippets are read from /usr/lib/systemd/*.conf.d/,
/usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/. Those
drop-ins have higher precedence and override the main configuration
file. Files in the *.conf.d/ configuration subdirectories are sorted by
their filename in lexicographic order, regardless of in which of the
subdirectories they reside. When multiple files specify the same
option, for options which accept just a single value, the entry in the
file sorted last takes precedence, and for options which accept a list
of values, entries are collected as they occur in the sorted files.
When packages need to customize the configuration, they can install
drop-ins under /usr/. Files in /etc/ are reserved for the local
administrator, who may use this logic to override the configuration
files installed by vendor packages. Drop-ins have to be used to
override package drop-ins, since the main configuration file has lower
precedence. It is recommended to prefix all filenames in those
subdirectories with a two-digit number and a dash, to simplify the
ordering of the files.
To disable a configuration file supplied by the vendor, the recommended
way is to place a symlink to /dev/null in the configuration directory
in /etc/, with the same filename as the vendor configuration file.
OPTIONS
All options are configured in the [Journal] section:
Storage=
Controls where to store journal data. One of "volatile",
"persistent", "auto" and "none". If "volatile", journal log data
will be stored only in memory, i.e. below the /run/log/journal
hierarchy (which is created if needed). If "persistent", data will
be stored preferably on disk, i.e. below the /var/log/journal
hierarchy (which is created if needed), with a fallback to
/run/log/journal (which is created if needed), during early boot
and if the disk is not writable. "auto" behaves like "persistent"
if the /var/log/journal directory exists, and "volatile" otherwise
(the existence of the directory controls the storage mode). "none"
turns off all storage, all log data received will be dropped (but
forwarding to other targets, such as the console, the kernel log
buffer, or a syslog socket will still work). Defaults to "auto" in
the default journal namespace, and "persistent" in all others.
Note that journald will initially use volatile storage, until a
call to journalctl --flush (or sending SIGUSR1 to journald) will
cause it to switch to persistent logging (under the conditions
mentioned above). This is done automatically on boot via
"systemd-journal-flush.service".
Note that when this option is changed to "volatile", existing
persistent data is not removed. In the other direction,
journalctl(1) with the --flush option may be used to move volatile
data to persistent storage.
When journal namespacing (see LogNamespace= in systemd.exec(5)) is
used, setting Storage= to "volatile" or "auto" will not have an
effect on the creation of the per-namespace logs directory in
/var/log/journal/, as the systemd-journald@.service service file by
default carries LogsDirectory=. To turn that off, add a unit file
drop-in file that sets LogsDirectory= to an empty string.
Compress=
Can take a boolean value. If enabled (the default), data objects
that shall be stored in the journal and are larger than the default
threshold of 512 bytes are compressed before they are written to
the file system. It can also be set to a number of bytes to specify
the compression threshold directly. Suffixes like K, M, and G can
be used to specify larger units.
Seal=
Takes a boolean value. If enabled (the default), and a sealing key
is available (as created by journalctl(1)'s --setup-keys command),
Forward Secure Sealing (FSS) for all persistent journal files is
enabled. FSS is based on Seekable Sequential Key Generators[1] by
G. A. Marson and B. Poettering (doi:10.1007/978-3-642-40203-6_7)
and may be used to protect journal files from unnoticed alteration.
SplitMode=
Controls whether to split up journal files per user, either "uid"
or "none". Split journal files are primarily useful for access
control: on UNIX/Linux access control is managed per file, and the
journal daemon will assign users read access to their journal
files. If "uid", all regular users (with UID outside the range of
system users, dynamic service users, and the nobody user) will each
get their own journal files, and system users will log to the
system journal. See Users, Groups, UIDs and GIDs on systemd
systems[2] for more details about UID ranges. If "none", journal
files are not split up by user and all messages are instead stored
in the single system journal. In this mode unprivileged users
generally do not have access to their own log data. Note that
splitting up journal files by user is only available for journals
stored persistently. If journals are stored on volatile storage
(see Storage= above), only a single journal file is used. Defaults
to "uid".
RateLimitIntervalSec=, RateLimitBurst=
Configures the rate limiting that is applied to all messages
generated on the system. If, in the time interval defined by
RateLimitIntervalSec=, more messages than specified in
RateLimitBurst= are logged by a service, all further messages
within the interval are dropped until the interval is over. A
message about the number of dropped messages is generated. This
rate limiting is applied per-service, so that two services which
log do not interfere with each other's limits. Defaults to 10000
messages in 30s. The time specification for RateLimitIntervalSec=
may be specified in the following units: "s", "min", "h", "ms",
"us". To turn off any kind of rate limiting, set either value to 0.
Note that the effective rate limit is multiplied by a factor
derived from the available free disk space for the journal.
Currently, this factor is calculated using the base 2 logarithm.
Table 1. Example RateLimitBurst= rate modifications by the
available disk space
┌─────────────────────┬──────────────────┐
│Available Disk Space │ Burst Multiplier │
├─────────────────────┼──────────────────┤
│<= 1MB │ 1 │
├─────────────────────┼──────────────────┤
│<= 16MB │ 2 │
├─────────────────────┼──────────────────┤
│<= 256MB │ 3 │
├─────────────────────┼──────────────────┤
│<= 4GB │ 4 │
├─────────────────────┼──────────────────┤
│<= 64GB │ 5 │
├─────────────────────┼──────────────────┤
│<= 1TB │ 6 │
└─────────────────────┴──────────────────┘
If a service provides rate limits for itself through
LogRateLimitIntervalSec= and/or LogRateLimitBurst= in
systemd.exec(5), those values will override the settings specified
here.
SystemMaxUse=, SystemKeepFree=, SystemMaxFileSize=, SystemMaxFiles=,
RuntimeMaxUse=, RuntimeKeepFree=, RuntimeMaxFileSize=, RuntimeMaxFiles=
Enforce size limits on the journal files stored. The options
prefixed with "System" apply to the journal files when stored on a
persistent file system, more specifically /var/log/journal. The
options prefixed with "Runtime" apply to the journal files when
stored on a volatile in-memory file system, more specifically
/run/log/journal. The former is used only when /var/ is mounted,
writable, and the directory /var/log/journal exists. Otherwise,
only the latter applies. Note that this means that during early
boot and if the administrator disabled persistent logging, only the
latter options apply, while the former apply if persistent logging
is enabled and the system is fully booted up. journalctl and
systemd-journald ignore all files with names not ending with
".journal" or ".journal~", so only such files, located in the
appropriate directories, are taken into account when calculating
current disk usage.
SystemMaxUse= and RuntimeMaxUse= control how much disk space the
journal may use up at most. SystemKeepFree= and RuntimeKeepFree=
control how much disk space systemd-journald shall leave free for
other uses. systemd-journald will respect both limits and use the
smaller of the two values.
The first pair defaults to 10% and the second to 15% of the size of
the respective file system, but each value is capped to 4G. If the
file system is nearly full and either SystemKeepFree= or
RuntimeKeepFree= are violated when systemd-journald is started, the
limit will be raised to the percentage that is actually free. This
means that if there was enough free space before and journal files
were created, and subsequently something else causes the file
system to fill up, journald will stop using more space, but it will
not be removing existing files to reduce the footprint again,
either. Also note that only archived files are deleted to reduce
the space occupied by journal files. This means that, in effect,
there might still be more space used than SystemMaxUse= or
RuntimeMaxUse= limit after a vacuuming operation is complete.
SystemMaxFileSize= and RuntimeMaxFileSize= control how large
individual journal files may grow at most. This influences the
granularity in which disk space is made available through rotation,
i.e. deletion of historic data. Defaults to one eighth of the
values configured with SystemMaxUse= and RuntimeMaxUse= capped to
128M, so that usually seven rotated journal files are kept as
history. If the journal compact mode is enabled (enabled by
default), the maximum file size is capped to 4G.
Specify values in bytes or use K, M, G, T, P, E as units for the
specified sizes (equal to 1024, 1024², ... bytes). Note that size
limits are enforced synchronously when journal files are extended,
and no explicit rotation step triggered by time is needed.
SystemMaxFiles= and RuntimeMaxFiles= control how many individual
journal files to keep at most. Note that only archived files are
deleted to reduce the number of files until this limit is reached;
active files will stay around. This means that, in effect, there
might still be more journal files around in total than this limit
after a vacuuming operation is complete. This setting defaults to
100.
MaxFileSec=
The maximum time to store entries in a single journal file before
rotating to the next one. Normally, time-based rotation should not
be required as size-based rotation with options such as
SystemMaxFileSize= should be sufficient to ensure that journal
files do not grow without bounds. However, to ensure that not too
much data is lost at once when old journal files are deleted, it
might make sense to change this value from the default of one
month. Set to 0 to turn off this feature. This setting takes time
values which may be suffixed with the units "year", "month",
"week", "day", "h" or "m" to override the default time unit of
seconds.
MaxRetentionSec=
The maximum time to store journal entries. This controls whether
journal files containing entries older than the specified time span
are deleted. Normally, time-based deletion of old journal files
should not be required as size-based deletion with options such as
SystemMaxUse= should be sufficient to ensure that journal files do
not grow without bounds. However, to enforce data retention
policies, it might make sense to change this value from the default
of 0 (which turns off this feature). This setting also takes time
values which may be suffixed with the units "year", "month",
"week", "day", "h" or " m" to override the default time unit of
seconds.
SyncIntervalSec=
The timeout before synchronizing journal files to disk. After
syncing, journal files are placed in the OFFLINE state. Note that
syncing is unconditionally done immediately after a log message of
priority CRIT, ALERT or EMERG has been logged. This setting hence
applies only to messages of the levels ERR, WARNING, NOTICE, INFO,
DEBUG. The default timeout is 5 minutes.
ForwardToSyslog=, ForwardToKMsg=, ForwardToConsole=, ForwardToWall=
Control whether log messages received by the journal daemon shall
be forwarded to a traditional syslog daemon, to the kernel log
buffer (kmsg), to the system console, or sent as wall messages to
all logged-in users. These options take boolean arguments. If
forwarding to syslog is enabled but nothing reads messages from the
socket, forwarding to syslog has no effect. By default, only
forwarding to syslog and wall is enabled. These settings may be
overridden at boot time with the kernel command line options
"systemd.journald.forward_to_syslog",
"systemd.journald.forward_to_kmsg",
"systemd.journald.forward_to_console", and
"systemd.journald.forward_to_wall". If the option name is specified
without "=" and the following argument, true is assumed. Otherwise,
the argument is parsed as a boolean.
When forwarding to the console, the TTY to log to can be changed
with TTYPath=, described below.
When forwarding to the kernel log buffer (kmsg), make sure to
select a suitably large size for the log buffer, for example by
adding "log_buf_len=8M" to the kernel command line. systemd will
automatically disable kernel's rate-limiting applied to userspace
processes (equivalent to setting "printk.devkmsg=on").
Note: Forwarding is performed synchronously within journald, and
may significantly affect its performance. This is particularly
relevant when using ForwardToConsole=yes in cloud environments,
where the console is often a slow, virtual serial port. Since
journald is implemented as a conventional single-process daemon,
forwarding to a completely hung console will block journald. This
can have a cascading effect resulting in any services synchronously
logging to the blocked journal also becoming blocked. Unless
actively debugging/developing something, it's generally preferable
to setup a journalctl --follow style service redirected to the
console, instead of ForwardToConsole=yes, for production use.
MaxLevelStore=, MaxLevelSyslog=, MaxLevelKMsg=, MaxLevelConsole=,
MaxLevelWall=
Controls the maximum log level of messages that are stored in the
journal, forwarded to syslog, kmsg, the console or wall (if that is
enabled, see above). As argument, takes one of "emerg", "alert",
"crit", "err", "warning", "notice", "info", "debug", or integer
values in the range of 0–7 (corresponding to the same levels).
Messages equal or below the log level specified are
stored/forwarded, messages above are dropped. Defaults to "debug"
for MaxLevelStore= and MaxLevelSyslog=, to ensure that the all
messages are stored in the journal and forwarded to syslog.
Defaults to "notice" for MaxLevelKMsg=, "info" for
MaxLevelConsole=, and "emerg" for MaxLevelWall=. These settings may
be overridden at boot time with the kernel command line options
"systemd.journald.max_level_store=",
"systemd.journald.max_level_syslog=",
"systemd.journald.max_level_kmsg=",
"systemd.journald.max_level_console=",
"systemd.journald.max_level_wall=".
ReadKMsg=
Takes a boolean value. If enabled systemd-journal processes
/dev/kmsg messages generated by the kernel. In the default journal
namespace this option is enabled by default, it is disabled in all
others.
Audit=
Takes a boolean value. If enabled systemd-journal will turn on
kernel auditing on start-up. If disabled it will turn it off. If
unset it will neither enable nor disable it, leaving the previous
state unchanged. Note that this option does not control whether
systemd-journald collects generated audit records, it just controls
whether it tells the kernel to generate them. This means if another
tool turns on auditing even if systemd-journald left it off, it
will still collect the generated messages. Defaults to off.
TTYPath=
Change the console TTY to use if ForwardToConsole=yes is used.
Defaults to /dev/console.
LineMax=
The maximum line length to permit when converting stream logs into
record logs. When a systemd unit's standard output/error are
connected to the journal via a stream socket, the data read is
split into individual log records at newline ("\n", ASCII 10) and
NUL characters. If no such delimiter is read for the specified
number of bytes a hard log record boundary is artificially
inserted, breaking up overly long lines into multiple log records.
Selecting overly large values increases the possible memory usage
of the Journal daemon for each stream client, as in the worst case
the journal daemon needs to buffer the specified number of bytes in
memory before it can flush a new log record to disk. Also note that
permitting overly large line maximum line lengths affects
compatibility with traditional log protocols as log records might
not fit anymore into a single AF_UNIX or AF_INET datagram. Takes a
size in bytes. If the value is suffixed with K, M, G or T, the
specified size is parsed as Kilobytes, Megabytes, Gigabytes, or
Terabytes (with the base 1024), respectively. Defaults to 48K,
which is relatively large but still small enough so that log
records likely fit into network datagrams along with extra room for
metadata. Note that values below 79 are not accepted and will be
bumped to 79.
FORWARDING TO TRADITIONAL SYSLOG DAEMONS
Journal events can be transferred to a different logging daemon in two
different ways. With the first method, messages are immediately
forwarded to a socket (/run/systemd/journal/syslog), where the
traditional syslog daemon can read them. This method is controlled by
the ForwardToSyslog= option. With a second method, a syslog daemon
behaves like a normal journal client, and reads messages from the
journal files, similarly to journalctl(1). With this, messages do not
have to be read immediately, which allows a logging daemon which is
only started late in boot to access all messages since the start of the
system. In addition, full structured meta-data is available to it. This
method of course is available only if the messages are stored in a
journal file at all. So it will not work if Storage=none is set. It
should be noted that usually the second method is used by syslog
daemons, so the Storage= option, and not the ForwardToSyslog= option,
is relevant for them.
SEE ALSO
systemd(1), systemd-journald.service(8), journalctl(1),
systemd.journal-fields(7), systemd-system.conf(5)
NOTES
1. Seekable Sequential Key Generators
https://eprint.iacr.org/2013/397
2. Users, Groups, UIDs and GIDs on systemd systems
https://systemd.io/UIDS-GIDS
systemd 252 JOURNALD.CONF(5)
Generated by dwww version 1.15 on Sun Jun 2 04:22:05 CEST 2024.