man/journald.conf.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="journald.conf"
   7     xmlns:xi="http://www.w3.org/2001/XInclude">
   8   <refentryinfo>
   9     <title>journald.conf</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>journald.conf</refentrytitle>
  15     <manvolnum>5</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>journald.conf</refname>
  20     <refname>journald.conf.d</refname>
  21     <refpurpose>Journal service configuration files</refpurpose>
  22   </refnamediv>
  23
  24   <refsynopsisdiv>
  25     <para><filename>/etc/systemd/journald.conf</filename></para>
  26     <para><filename>/etc/systemd/journald.conf.d/*.conf</filename></para>
  27     <para><filename>/run/systemd/journald.conf.d/*.conf</filename></para>
  28     <para><filename>/usr/lib/systemd/journald.conf.d/*.conf</filename></para>
  29   </refsynopsisdiv>
  30
  31   <refsect1>
  32     <title>Description</title>
  33
  34     <para>These files configure various parameters of the systemd journal service,
  35     <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  36     See
  37     <citerefentry><refentrytitle>systemd.syntax</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  38     for a general description of the syntax.</para>
  39
  40   </refsect1>
  41
  42   <xi:include href="standard-conf.xml" xpointer="main-conf" />
  43
  44   <refsect1>
  45     <title>Options</title>
  46
  47     <para>All options are configured in the
  48     <literal>[Journal]</literal> section:</para>
  49
  50     <variablelist class='config-directives'>
  51
  52       <varlistentry>
  53         <term><varname>Storage=</varname></term>
  54
  55         <listitem><para>Controls where to store journal data. One of
  56         <literal>volatile</literal>,
  57         <literal>persistent</literal>,
  58         <literal>auto</literal> and
  59         <literal>none</literal>. If
  60         <literal>volatile</literal>, journal
  61         log data will be stored only in memory, i.e. below the
  62         <filename>/run/log/journal</filename> hierarchy (which is
  63         created if needed). If <literal>persistent</literal>, data
  64         will be stored preferably on disk, i.e. below the
  65         <filename>/var/log/journal</filename> hierarchy (which is
  66         created if needed), with a fallback to
  67         <filename>/run/log/journal</filename> (which is created if
  68         needed), during early boot and if the disk is not writable.
  69         <literal>auto</literal> is similar to
  70         <literal>persistent</literal> but the directory
  71         <filename>/var/log/journal</filename> is not created if
  72         needed, so that its existence controls where log data goes.
  73         <literal>none</literal> turns off all storage, all log data
  74         received will be dropped. Forwarding to other targets, such as
  75         the console, the kernel log buffer, or a syslog socket will
  76         still work however. Defaults to
  77         <literal>auto</literal>.</para></listitem>
  78       </varlistentry>
  79
  80       <varlistentry>
  81         <term><varname>Compress=</varname></term>
  82
  83         <listitem><para>Can take a boolean value. If enabled (the
  84         default), data objects that shall be stored in the journal
  85         and are larger than the default threshold of 512 bytes are
  86         compressed before they are written to the file system. It
  87         can also be set to a number of bytes to specify the
  88         compression threshold directly. Suffixes like K, M, and G
  89         can be used to specify larger units.</para></listitem>
  90       </varlistentry>
  91
  92       <varlistentry>
  93         <term><varname>Seal=</varname></term>
  94
  95         <listitem><para>Takes a boolean value. If enabled (the
  96         default), and a sealing key is available (as created by
  97         <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
  98         <option>--setup-keys</option> command), Forward Secure Sealing
  99         (FSS) for all persistent journal files is enabled. FSS is
 100         based on <ulink
 101         url="https://eprint.iacr.org/2013/397">Seekable Sequential Key
 102         Generators</ulink> by G. A. Marson and B. Poettering
 103         (doi:10.1007/978-3-642-40203-6_7) and may be used to protect
 104         journal files from unnoticed alteration.</para></listitem>
 105       </varlistentry>
 106
 107       <varlistentry>
 108         <term><varname>SplitMode=</varname></term>
 109
 110         <listitem><para>Controls whether to split up journal files per user, either <literal>uid</literal> or
 111         <literal>none</literal>. Split journal files are primarily useful for access control: on UNIX/Linux access
 112         control is managed per file, and the journal daemon will assign users read access to their journal files. If
 113         <literal>uid</literal>, all regular users will each get their own journal files, and system users will log to
 114         the system journal. If <literal>none</literal>, journal files are not split up by user and all messages are
 115         instead stored in the single system journal. In this mode unprivileged users generally do not have access to
 116         their own log data. Note that splitting up journal files by user is only available for journals stored
 117         persistently. If journals are stored on volatile storage (see <varname>Storage=</varname> above), only a single
 118         journal file is used. Defaults to <literal>uid</literal>.</para></listitem>
 119       </varlistentry>
 120
 121       <varlistentry>
 122         <term><varname>RateLimitIntervalSec=</varname></term>
 123         <term><varname>RateLimitBurst=</varname></term>
 124
 125         <listitem><para>Configures the rate limiting that is applied
 126         to all messages generated on the system. If, in the time
 127         interval defined by <varname>RateLimitIntervalSec=</varname>,
 128         more messages than specified in
 129         <varname>RateLimitBurst=</varname> are logged by a service,
 130         all further messages within the interval are dropped until the
 131         interval is over. A message about the number of dropped
 132         messages is generated. This rate limiting is applied
 133         per-service, so that two services which log do not interfere
 134         with each other's limits. Defaults to 10000 messages in 30s.
 135         The time specification for
 136         <varname>RateLimitIntervalSec=</varname> may be specified in the
 137         following units: <literal>s</literal>, <literal>min</literal>,
 138         <literal>h</literal>, <literal>ms</literal>,
 139         <literal>us</literal>. To turn off any kind of rate limiting,
 140         set either value to 0.</para>
 141
 142         <para>If a service provides rate limits for itself through
 143         <varname>LogRateLimitIntervalSec=</varname> and/or <varname>LogRateLimitBurst=</varname>
 144         in <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 145         those values will override the settings specified here.</para>
 146         </listitem>
 147       </varlistentry>
 148
 149       <varlistentry>
 150         <term><varname>SystemMaxUse=</varname></term>
 151         <term><varname>SystemKeepFree=</varname></term>
 152         <term><varname>SystemMaxFileSize=</varname></term>
 153         <term><varname>SystemMaxFiles=</varname></term>
 154         <term><varname>RuntimeMaxUse=</varname></term>
 155         <term><varname>RuntimeKeepFree=</varname></term>
 156         <term><varname>RuntimeMaxFileSize=</varname></term>
 157         <term><varname>RuntimeMaxFiles=</varname></term>
 158
 159         <listitem><para>Enforce size limits on the journal files
 160         stored. The options prefixed with <literal>System</literal>
 161         apply to the journal files when stored on a persistent file
 162         system, more specifically
 163         <filename>/var/log/journal</filename>. The options prefixed
 164         with <literal>Runtime</literal> apply to the journal files
 165         when stored on a volatile in-memory file system, more
 166         specifically <filename>/run/log/journal</filename>. The former
 167         is used only when <filename>/var</filename> is mounted,
 168         writable, and the directory
 169         <filename>/var/log/journal</filename> exists. Otherwise, only
 170         the latter applies. Note that this means that during early
 171         boot and if the administrator disabled persistent logging,
 172         only the latter options apply, while the former apply if
 173         persistent logging is enabled and the system is fully booted
 174         up. <command>journalctl</command> and
 175         <command>systemd-journald</command> ignore all files with
 176         names not ending with <literal>.journal</literal> or
 177         <literal>.journal~</literal>, so only such files, located in
 178         the appropriate directories, are taken into account when
 179         calculating current disk usage.</para>
 180
 181         <para><varname>SystemMaxUse=</varname> and
 182         <varname>RuntimeMaxUse=</varname> control how much disk space
 183         the journal may use up at most.
 184         <varname>SystemKeepFree=</varname> and
 185         <varname>RuntimeKeepFree=</varname> control how much disk
 186         space systemd-journald shall leave free for other uses.
 187         <command>systemd-journald</command> will respect both limits
 188         and use the smaller of the two values.</para>
 189
 190         <para>The first pair defaults to 10% and the second to 15% of
 191         the size of the respective file system, but each value is
 192         capped to 4G. If the file system is nearly full and either
 193         <varname>SystemKeepFree=</varname> or
 194         <varname>RuntimeKeepFree=</varname> are violated when
 195         systemd-journald is started, the limit will be raised to the
 196         percentage that is actually free. This means that if there was
 197         enough free space before and journal files were created, and
 198         subsequently something else causes the file system to fill up,
 199         journald will stop using more space, but it will not be
 200         removing existing files to reduce the footprint again,
 201         either. Also note that only archived files are deleted to reduce the
 202         space occupied by journal files. This means that, in effect, there might
 203         still be more space used than <varname>SystemMaxUse=</varname> or
 204         <varname>RuntimeMaxUse=</varname> limit after a vacuuming operation is
 205         complete.</para>
 206
 207         <para><varname>SystemMaxFileSize=</varname> and
 208         <varname>RuntimeMaxFileSize=</varname> control how large
 209         individual journal files may grow at most. This influences
 210         the granularity in which disk space is made available through
 211         rotation, i.e. deletion of historic data. Defaults to one
 212         eighth of the values configured with
 213         <varname>SystemMaxUse=</varname> and
 214         <varname>RuntimeMaxUse=</varname>, so that usually seven
 215         rotated journal files are kept as history.</para>
 216
 217         <para>Specify values in bytes or use K, M, G, T, P, E as
 218         units for the specified sizes (equal to 1024, 1024², … bytes).
 219         Note that size limits are enforced synchronously when journal
 220         files are extended, and no explicit rotation step triggered by
 221         time is needed.</para>
 222
 223         <para><varname>SystemMaxFiles=</varname> and
 224         <varname>RuntimeMaxFiles=</varname> control how many
 225         individual journal files to keep at most. Note that only
 226         archived files are deleted to reduce the number of files until
 227         this limit is reached; active files will stay around. This
 228         means that, in effect, there might still be more journal files
 229         around in total than this limit after a vacuuming operation is
 230         complete. This setting defaults to 100.</para></listitem>
 231       </varlistentry>
 232
 233       <varlistentry>
 234         <term><varname>MaxFileSec=</varname></term>
 235
 236         <listitem><para>The maximum time to store entries in a single
 237         journal file before rotating to the next one. Normally,
 238         time-based rotation should not be required as size-based
 239         rotation with options such as
 240         <varname>SystemMaxFileSize=</varname> should be sufficient to
 241         ensure that journal files do not grow without bounds. However,
 242         to ensure that not too much data is lost at once when old
 243         journal files are deleted, it might make sense to change this
 244         value from the default of one month. Set to 0 to turn off this
 245         feature. This setting takes time values which may be suffixed
 246         with the units <literal>year</literal>,
 247         <literal>month</literal>, <literal>week</literal>,
 248         <literal>day</literal>, <literal>h</literal> or
 249         <literal>m</literal> to override the default time unit of
 250         seconds.</para></listitem>
 251       </varlistentry>
 252
 253       <varlistentry>
 254         <term><varname>MaxRetentionSec=</varname></term>
 255
 256         <listitem><para>The maximum time to store journal entries.
 257         This controls whether journal files containing entries older
 258         than the specified time span are deleted. Normally, time-based
 259         deletion of old journal files should not be required as
 260         size-based deletion with options such as
 261         <varname>SystemMaxUse=</varname> should be sufficient to
 262         ensure that journal files do not grow without bounds. However,
 263         to enforce data retention policies, it might make sense to
 264         change this value from the default of 0 (which turns off this
 265         feature). This setting also takes time values which may be
 266         suffixed with the units <literal>year</literal>,
 267         <literal>month</literal>, <literal>week</literal>,
 268         <literal>day</literal>, <literal>h</literal> or <literal>
 269         m</literal> to override the default time unit of
 270         seconds.</para></listitem>
 271       </varlistentry>
 272
 273       <varlistentry>
 274         <term><varname>SyncIntervalSec=</varname></term>
 275
 276         <listitem><para>The timeout before synchronizing journal files
 277         to disk. After syncing, journal files are placed in the
 278         OFFLINE state. Note that syncing is unconditionally done
 279         immediately after a log message of priority CRIT, ALERT or
 280         EMERG has been logged. This setting hence applies only to
 281         messages of the levels ERR, WARNING, NOTICE, INFO, DEBUG. The
 282         default timeout is 5 minutes. </para></listitem>
 283       </varlistentry>
 284
 285       <varlistentry>
 286         <term><varname>ForwardToSyslog=</varname></term>
 287         <term><varname>ForwardToKMsg=</varname></term>
 288         <term><varname>ForwardToConsole=</varname></term>
 289         <term><varname>ForwardToWall=</varname></term>
 290
 291         <listitem><para>Control whether log messages received by the journal daemon shall be forwarded to a
 292         traditional syslog daemon, to the kernel log buffer (kmsg), to the system console, or sent as wall
 293         messages to all logged-in users.  These options take boolean arguments. If forwarding to syslog is
 294         enabled but nothing reads messages from the socket, forwarding to syslog has no effect. By default,
 295         only forwarding to wall is enabled. These settings may be overridden at boot time with the kernel
 296         command line options <literal>systemd.journald.forward_to_syslog</literal>,
 297         <literal>systemd.journald.forward_to_kmsg</literal>,
 298         <literal>systemd.journald.forward_to_console</literal>, and
 299         <literal>systemd.journald.forward_to_wall</literal>. If the option name is specified without
 300         <literal>=</literal> and the following argument, true is assumed. Otherwise, the argument is parsed
 301         as a boolean.</para>
 302
 303         <para>When forwarding to the console, the TTY to log to can be changed with
 304         <varname>TTYPath=</varname>, described below.</para>
 305
 306         <para>When forwarding to the kernel log buffer (kmsg), make sure to select a suitably large size for
 307         the log buffer, and ensure the kernel's rate-limiting applied to userspace processes is turned
 308         off. Specifically, add <literal>log_buf_len=8M</literal> and <literal>printk.devkmsg=on</literal> (or
 309         similar) to the kernel command line.</para></listitem>
 310       </varlistentry>
 311
 312       <varlistentry>
 313         <term><varname>MaxLevelStore=</varname></term>
 314         <term><varname>MaxLevelSyslog=</varname></term>
 315         <term><varname>MaxLevelKMsg=</varname></term>
 316         <term><varname>MaxLevelConsole=</varname></term>
 317         <term><varname>MaxLevelWall=</varname></term>
 318
 319         <listitem><para>Controls the maximum log level of messages
 320         that are stored on disk, forwarded to syslog, kmsg, the
 321         console or wall (if that is enabled, see above). As argument,
 322         takes one of
 323         <literal>emerg</literal>,
 324         <literal>alert</literal>,
 325         <literal>crit</literal>,
 326         <literal>err</literal>,
 327         <literal>warning</literal>,
 328         <literal>notice</literal>,
 329         <literal>info</literal>,
 330         <literal>debug</literal>,
 331         or integer values in the range of 0–7 (corresponding to the
 332         same levels). Messages equal or below the log level specified
 333         are stored/forwarded, messages above are dropped. Defaults to
 334         <literal>debug</literal> for <varname>MaxLevelStore=</varname>
 335         and <varname>MaxLevelSyslog=</varname>, to ensure that the all
 336         messages are written to disk and forwarded to syslog. Defaults
 337         to
 338         <literal>notice</literal> for <varname>MaxLevelKMsg=</varname>,
 339         <literal>info</literal> for <varname>MaxLevelConsole=</varname>,
 340         and <literal>emerg</literal> for
 341         <varname>MaxLevelWall=</varname>. These settings may be
 342         overridden at boot time with the kernel command line options
 343         <literal>systemd.journald.max_level_store=</literal>,
 344         <literal>systemd.journald.max_level_syslog=</literal>,
 345         <literal>systemd.journald.max_level_kmsg=</literal>,
 346         <literal>systemd.journald.max_level_console=</literal>,
 347         <literal>systemd.journald.max_level_wall=</literal>.</para>
 348         </listitem>
 349       </varlistentry>
 350
 351       <varlistentry>
 352         <term><varname>ReadKMsg=</varname></term>
 353
 354         <listitem><para>Takes a boolean value. If enabled (the
 355         default), journal reads <filename>/dev/kmsg</filename>
 356         messages generated by the kernel.</para></listitem>
 357       </varlistentry>
 358
 359       <varlistentry>
 360         <term><varname>TTYPath=</varname></term>
 361
 362         <listitem><para>Change the console TTY to use if
 363         <varname>ForwardToConsole=yes</varname> is used. Defaults to
 364         <filename>/dev/console</filename>.</para></listitem>
 365       </varlistentry>
 366
 367       <varlistentry>
 368         <term><varname>LineMax=</varname></term>
 369
 370         <listitem><para>The maximum line length to permit when converting stream logs into record logs. When a systemd
 371         unit's standard output/error are connected to the journal via a stream socket, the data read is split into
 372         individual log records at newline (<literal>\n</literal>, ASCII 10) and NUL characters. If no such delimiter is
 373         read for the specified number of bytes a hard log record boundary is artificially inserted, breaking up overly
 374         long lines into multiple log records. Selecting overly large values increases the possible memory usage of the
 375         Journal daemon for each stream client, as in the worst case the journal daemon needs to buffer the specified
 376         number of bytes in memory before it can flush a new log record to disk. Also note that permitting overly large
 377         line maximum line lengths affects compatibility with traditional log protocols as log records might not fit
 378         anymore into a single <constant>AF_UNIX</constant> or <constant>AF_INET</constant> datagram. Takes a size in
 379         bytes. If the value is suffixed with K, M, G or T, the specified size is parsed as Kilobytes, Megabytes,
 380         Gigabytes, or Terabytes (with the base 1024), respectively. Defaults to 48K, which is relatively large but
 381         still small enough so that log records likely fit into network datagrams along with extra room for
 382         metadata. Note that values below 79 are not accepted and will be bumped to 79.</para></listitem>
 383       </varlistentry>
 384
 385     </variablelist>
 386
 387   </refsect1>
 388
 389   <refsect1>
 390     <title>Forwarding to traditional syslog daemons</title>
 391
 392     <para>
 393       Journal events can be transferred to a different logging daemon
 394       in two different ways. With the first method, messages are
 395       immediately forwarded to a socket
 396       (<filename>/run/systemd/journal/syslog</filename>), where the
 397       traditional syslog daemon can read them. This method is
 398       controlled by the <varname>ForwardToSyslog=</varname> option. With a
 399       second method, a syslog daemon behaves like a normal journal
 400       client, and reads messages from the journal files, similarly to
 401       <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
 402       With this, messages do not have to be read immediately,
 403       which allows a logging daemon which is only started late in boot
 404       to access all messages since the start of the system. In
 405       addition, full structured meta-data is available to it. This
 406       method of course is available only if the messages are stored in
 407       a journal file at all. So it will not work if
 408       <varname>Storage=none</varname> is set. It should be noted that
 409       usually the <emphasis>second</emphasis> method is used by syslog
 410       daemons, so the <varname>Storage=</varname> option, and not the
 411       <varname>ForwardToSyslog=</varname> option, is relevant for them.
 412     </para>
 413   </refsect1>
 414
 415   <refsect1>
 416       <title>See Also</title>
 417       <para>
 418         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 419         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 420         <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 421         <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 422         <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 423       </para>
 424   </refsect1>
 425
 426 </refentry>