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

       The 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. When multiple files specify the same option, for options which accept just
       a single value, the entry in the file with the lexicographically latest name takes
       precedence. For options which accept a list of values, entries are collected as they occur
       in files sorted lexicographically. 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, 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 will each get their own journal files, and
           system users will log to the system journal. 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 1000 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.

       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.

           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=, 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.

           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 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". 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.

       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=. 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 (the default), journal reads /dev/kmsg messages
           generated by the kernel.

       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