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JOURNALD.CONF(5) journald.conf JOURNALD.CONF(5)
NAME
journald.conf, journald.conf.d - 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
DESCRIPTION
These files configure various parameters of the systemd journal service, systemd-
journald.service(8).
CONFIGURATION DIRECTORIES AND PRECEDENCE
Default configuration is defined during compilation, so a configuration file is only
needed when it is necessary to deviate from those defaults. By default the configuration
file in /etc/systemd/ contains commented out entries showing the defaults as a guide to
the administrator. This file can be edited to create local overrides.
When packages need to customize the configuration, they can install configuration snippets
in /usr/lib/systemd/*.conf.d/. Files in /etc/ are reserved for the local administrator,
who may use this logic to override the configuration files installed by vendor packages.
The main configuration file is read before any of the configuration directories, and has
the lowest precedence; entries in a file in any configuration directory override entries
in the single configuration file. Files in the *.conf.d/ configuration subdirectories are
sorted by their filename in lexicographic order, regardless of which of the subdirectories
they reside in. If multiple files specify the same option, the entry in the file with the
lexicographically latest name takes 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" is similar to "persistent" but the
directory /var/log/journal is not created if needed, so that its existence controls
where log data goes. "none" turns off all storage, all log data received will be
dropped. Forwarding to other targets, such as the console, the kernel log buffer, or a
syslog socket will still work however. Defaults to "auto".
Compress=
Takes a boolean value. If enabled (the default), data objects that shall be stored in
the journal and are larger than a certain threshold are compressed before they are
written to the file system.
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. One of "uid", "login" and "none".
If "uid", all users will get each their own journal files regardless of whether they
possess a login session or not, however system users will log into the system journal.
If "login", actually logged-in users will get each their own journal files, but users
without login session and system users will log into the system journal. If "none",
journal files are not split up by user and all messages are instead stored in the
single system journal. Note that splitting up journal files by user is only available
for journals stored persistently. If journals are stored on volatile storage (see
above), only a single journal file for all user IDs is kept. Defaults to "uid".
RateLimitInterval=, RateLimitBurst=
Configures the rate limiting that is applied to all messages generated on the system.
If, in the time interval defined by RateLimitInterval=, 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 1000 messages in 30s. The
time specification for RateLimitInterval= 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.
SystemMaxUse=, SystemKeepFree=, SystemMaxFileSize=, RuntimeMaxUse=, RuntimeKeepFree=,
RuntimeMaxFileSize=
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
maximum. 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= is violated when systemd-journald is
started, the value will be raised to 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 go reduce footprint either.
SystemMaxFileSize= and RuntimeMaxFileSize= control how large individual journal files
may grow at maximum. 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=, so that usually seven
rotated journal files are kept as history. 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.
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 then 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=". When
forwarding to the console, the TTY to log to can be changed with TTYPath=, described
below.
MaxLevelStore=, MaxLevelSyslog=, MaxLevelKMsg=, MaxLevelConsole=, MaxLevelWall=
Controls the maximum log level of messages that are stored on disk, 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 written to disk and forwarded to syslog. Defaults to "notice" for
MaxLevelKMsg=, "info" for MaxLevelConsole=, and "emerg" for MaxLevelWall=.
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 artifically 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. In
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 ForwardToSyslog= option. In a second method, a syslog daemon
behaves like a normal journal client, and reads messages from the journal files, similarly
to journalctl(1). In this method, 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
systemd 219 JOURNALD.CONF(5)
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