mirror of
https://github.com/systemd/systemd-stable.git
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ec20fe5ffb
This adds a new setting LineMax= to journald.conf, and sets it by default to 48K. When we convert stream-based stdout/stderr logging into record-based log entries, read up to the specified amount of bytes before forcing a line-break. This also makes three related changes: - When a NUL byte is read we'll not recognize this as alternative line break, instead of silently dropping everything after it. (see #4863) - The reason for a line-break is now encoded in the log record, if it wasn't a plain newline. Specifically, we distuingish "nul", "line-max" and "eof", for line breaks due to NUL byte, due to the maximum line length as configured with LineMax= or due to end of stream. This data is stored in the new implicit _LINE_BREAK= field. It's not synthesized for plain \n line breaks. - A randomized 128bit ID is assigned to each log stream. With these three changes in place it's (mostly) possible to reconstruct the original byte streams from log data, as (most) of the context of the conversion from the byte stream to log records is saved now. (So, the only bits we still drop are empty lines. Which might be something to look into in a future change, and which is outside of the scope of this work) Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=86465 See: #4863 Replaces: #4875
560 lines
21 KiB
XML
560 lines
21 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd.journal-fields">
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<refentryinfo>
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<title>systemd.journal-fields</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.journal-fields</refentrytitle>
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<manvolnum>7</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.journal-fields</refname>
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<refpurpose>Special journal fields</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<para>Entries in the journal resemble an environment block in
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their syntax but with fields that can include binary data.
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Primarily, fields are formatted UTF-8 text strings, and binary
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formatting is used only where formatting as UTF-8 text strings
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makes little sense. New fields may freely be defined by
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applications, but a few fields have special meaning. All fields
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with special meanings are optional. In some cases, fields may
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appear more than once per entry.</para>
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</refsect1>
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<refsect1>
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<title>User Journal Fields</title>
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<para>User fields are fields that are directly passed from clients
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and stored in the journal.</para>
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<variablelist class='journal-directives'>
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<varlistentry>
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<term><varname>MESSAGE=</varname></term>
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<listitem>
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<para>The human-readable message string for this entry. This
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is supposed to be the primary text shown to the user. It is
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usually not translated (but might be in some cases), and is
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not supposed to be parsed for metadata.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>MESSAGE_ID=</varname></term>
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<listitem>
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<para>A 128-bit message identifier ID for recognizing
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certain message types, if this is desirable. This should
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contain a 128-bit ID formatted as a lower-case hexadecimal
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string, without any separating dashes or suchlike. This is
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recommended to be a UUID-compatible ID, but this is not
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enforced, and formatted differently. Developers can generate
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a new ID for this purpose with <command>journalctl
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<option>--new-id128</option></command>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>PRIORITY=</varname></term>
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<listitem>
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<para>A priority value between 0 (<literal>emerg</literal>)
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and 7 (<literal>debug</literal>) formatted as a decimal
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string. This field is compatible with syslog's priority
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concept.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>CODE_FILE=</varname></term>
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<term><varname>CODE_LINE=</varname></term>
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<term><varname>CODE_FUNC=</varname></term>
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<listitem>
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<para>The code location generating this message, if known.
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Contains the source filename, the line number and the
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function name.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>ERRNO=</varname></term>
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<listitem>
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<para>The low-level Unix error number causing this entry, if
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any. Contains the numeric value of
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<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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formatted as a decimal string.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>SYSLOG_FACILITY=</varname></term>
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<term><varname>SYSLOG_IDENTIFIER=</varname></term>
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<term><varname>SYSLOG_PID=</varname></term>
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<listitem>
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<para>Syslog compatibility fields containing the facility
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(formatted as decimal string), the identifier string (i.e.
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"tag"), and the client PID. (Note that the tag is usually
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derived from glibc's
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<varname>program_invocation_short_name</varname> variable,
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see
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<citerefentry project='die-net'><refentrytitle>program_invocation_short_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>.)</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Trusted Journal Fields</title>
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<para>Fields prefixed with an underscore are trusted fields, i.e.
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fields that are implicitly added by the journal and cannot be
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altered by client code.</para>
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<variablelist class='journal-directives'>
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<varlistentry>
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<term><varname>_PID=</varname></term>
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<term><varname>_UID=</varname></term>
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<term><varname>_GID=</varname></term>
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<listitem>
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<para>The process, user, and group ID of the process the
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journal entry originates from formatted as a decimal
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string. Note that entries obtained via <literal>stdout</literal> or
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<literal>stderr</literal> of forked processes will contain credentials valid for a parent
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process (that initiated the connection to <command>systemd-journald</command>).</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_COMM=</varname></term>
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<term><varname>_EXE=</varname></term>
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<term><varname>_CMDLINE=</varname></term>
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<listitem>
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<para>The name, the executable path, and the command line of
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the process the journal entry originates from.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_CAP_EFFECTIVE=</varname></term>
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<listitem>
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<para>The effective
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<citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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of the process the journal entry originates from.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_AUDIT_SESSION=</varname></term>
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<term><varname>_AUDIT_LOGINUID=</varname></term>
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<listitem>
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<para>The session and login UID of the process the journal
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entry originates from, as maintained by the kernel audit
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subsystem.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_SYSTEMD_CGROUP=</varname></term>
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<term><varname>_SYSTEMD_SESSION=</varname></term>
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<term><varname>_SYSTEMD_UNIT=</varname></term>
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<term><varname>_SYSTEMD_USER_UNIT=</varname></term>
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<term><varname>_SYSTEMD_OWNER_UID=</varname></term>
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<term><varname>_SYSTEMD_SLICE=</varname></term>
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<listitem>
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<para>The control group path in the systemd hierarchy, the
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systemd session ID (if any), the systemd unit name (if any),
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the systemd user session unit name (if any), the owner UID
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of the systemd session (if any) and the systemd slice unit
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of the process the journal entry originates from.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_SELINUX_CONTEXT=</varname></term>
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<listitem>
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<para>The SELinux security context (label) of the process
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the journal entry originates from.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_SOURCE_REALTIME_TIMESTAMP=</varname></term>
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<listitem>
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<para>The earliest trusted timestamp of the message, if any
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is known that is different from the reception time of the
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journal. This is the time in microseconds since the epoch
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UTC, formatted as a decimal string.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_BOOT_ID=</varname></term>
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<listitem>
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<para>The kernel boot ID for the boot the message was
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generated in, formatted as a 128-bit hexadecimal
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string.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_MACHINE_ID=</varname></term>
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<listitem>
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<para>The machine ID of the originating host, as available
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in
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<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_SYSTEMD_INVOCATION_ID=</varname></term>
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<listitem>
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<para>The invocation ID for the runtime cycle of the unit
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the message was generated in, as available to processes
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of the unit in <varname>$INVOCATION_ID</varname> (see
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<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>).</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_HOSTNAME=</varname></term>
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<listitem>
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<para>The name of the originating host.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_TRANSPORT=</varname></term>
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<listitem>
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<para>How the entry was received by the journal service.
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Valid transports are:
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</para>
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<variablelist>
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<varlistentry>
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<term>
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<option>audit</option>
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</term>
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<listitem>
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<para>for those read from the kernel audit subsystem
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<option>driver</option>
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</term>
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<listitem>
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<para>for internally generated messages
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<option>syslog</option>
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</term>
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<listitem>
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<para>for those received via the local syslog socket
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with the syslog protocol
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<option>journal</option>
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</term>
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<listitem>
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<para>for those received via the native journal
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protocol
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<option>stdout</option>
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</term>
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<listitem>
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<para>for those read from a service's standard output
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or error output
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<option>kernel</option>
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</term>
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<listitem>
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<para>for those read from the kernel
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_STREAM_ID=</varname></term>
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<listitem>
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<para>Only applies to <literal>_TRANSPORT=stream</literal> records: specifies a randomized 128bit ID assigned
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to the stream connection when it was first created. This ID is useful to reconstruct individual log streams
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from the log records: all log records carrying the same stream ID originate from the same stream.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_LINE_BREAK=</varname></term>
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<listitem>
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<para>Only applies to <literal>_TRANSPORT=stream</literal> records: indicates that the log message in the
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standard output/error stream was not terminated with a normal newline character (<literal>\n</literal>,
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i.e. ASCII 10). Specifically, when set this field is one of <option>nul</option> (in case the line was
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terminated by a NUL byte), <option>line-max</option> (in case the maximum log line length was reached, as
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configured with <varname>LineMax=</varname> in
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<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>) or
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<option>eof</option> (if this was the last log record of a stream and the stream ended without a final
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newline character). Note that this record is not generated when a normal newline character was used for
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marking the log line end.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Kernel Journal Fields</title>
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<para>Kernel fields are fields that are used by messages
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originating in the kernel and stored in the journal.</para>
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<variablelist class='journal-directives'>
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<varlistentry>
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<term><varname>_KERNEL_DEVICE=</varname></term>
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<listitem>
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<para>The kernel device name. If the entry is associated to
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a block device, the major and minor of the device node,
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separated by <literal>:</literal> and prefixed by
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<literal>b</literal>. Similar for character devices but
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prefixed by <literal>c</literal>. For network devices, this
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is the interface index prefixed by <literal>n</literal>. For
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all other devices, this is the subsystem name prefixed by
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<literal>+</literal>, followed by <literal>:</literal>,
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followed by the kernel device name.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_KERNEL_SUBSYSTEM=</varname></term>
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<listitem>
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<para>The kernel subsystem name.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_UDEV_SYSNAME=</varname></term>
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<listitem>
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<para>The kernel device name as it shows up in the device
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tree below <filename>/sys</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_UDEV_DEVNODE=</varname></term>
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<listitem>
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<para>The device node path of this device in
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<filename>/dev</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>_UDEV_DEVLINK=</varname></term>
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<listitem>
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<para>Additional symlink names pointing to the device node
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in <filename>/dev</filename>. This field is frequently set
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more than once per entry.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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|
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<refsect1>
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<title>Fields to log on behalf of a different program</title>
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|
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<para>Fields in this section are used by programs to specify that
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they are logging on behalf of another program or unit.
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</para>
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<para>Fields used by the <command>systemd-coredump</command>
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coredump kernel helper:
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</para>
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<variablelist class='journal-directives'>
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<varlistentry>
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<term><varname>COREDUMP_UNIT=</varname></term>
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<term><varname>COREDUMP_USER_UNIT=</varname></term>
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<listitem>
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<para>Used to annotate messages containing coredumps from
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system and session units. See
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<citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>Privileged programs (currently UID 0) may attach
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<varname>OBJECT_PID=</varname> to a message. This will instruct
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<command>systemd-journald</command> to attach additional fields on
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behalf of the caller:</para>
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<variablelist class='journal-directives'>
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<varlistentry>
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<term><varname>OBJECT_PID=<replaceable>PID</replaceable></varname></term>
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<listitem>
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<para>PID of the program that this message pertains to.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>OBJECT_UID=</varname></term>
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<term><varname>OBJECT_GID=</varname></term>
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<term><varname>OBJECT_COMM=</varname></term>
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<term><varname>OBJECT_EXE=</varname></term>
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<term><varname>OBJECT_CMDLINE=</varname></term>
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<term><varname>OBJECT_AUDIT_SESSION=</varname></term>
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<term><varname>OBJECT_AUDIT_LOGINUID=</varname></term>
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<term><varname>OBJECT_SYSTEMD_CGROUP=</varname></term>
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<term><varname>OBJECT_SYSTEMD_SESSION=</varname></term>
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<term><varname>OBJECT_SYSTEMD_OWNER_UID=</varname></term>
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<term><varname>OBJECT_SYSTEMD_UNIT=</varname></term>
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<term><varname>OBJECT_SYSTEMD_USER_UNIT=</varname></term>
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<listitem>
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<para>These are additional fields added automatically by
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<command>systemd-journald</command>. Their meaning is the
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same as
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<varname>_UID=</varname>,
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<varname>_GID=</varname>,
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<varname>_COMM=</varname>,
|
|
<varname>_EXE=</varname>,
|
|
<varname>_CMDLINE=</varname>,
|
|
<varname>_AUDIT_SESSION=</varname>,
|
|
<varname>_AUDIT_LOGINUID=</varname>,
|
|
<varname>_SYSTEMD_CGROUP=</varname>,
|
|
<varname>_SYSTEMD_SESSION=</varname>,
|
|
<varname>_SYSTEMD_UNIT=</varname>,
|
|
<varname>_SYSTEMD_USER_UNIT=</varname>, and
|
|
<varname>_SYSTEMD_OWNER_UID=</varname>
|
|
as described above, except that the process identified by
|
|
<replaceable>PID</replaceable> is described, instead of the
|
|
process which logged the message.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Address Fields</title>
|
|
|
|
<para>During serialization into external formats, such as the
|
|
<ulink
|
|
url="https://www.freedesktop.org/wiki/Software/systemd/export">Journal
|
|
Export Format</ulink> or the <ulink
|
|
url="https://www.freedesktop.org/wiki/Software/systemd/json">Journal
|
|
JSON Format</ulink>, the addresses of journal entries are
|
|
serialized into fields prefixed with double underscores. Note that
|
|
these are not proper fields when stored in the journal but for
|
|
addressing metadata of entries. They cannot be written as part of
|
|
structured log entries via calls such as
|
|
<citerefentry><refentrytitle>sd_journal_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
|
They may also not be used as matches for
|
|
<citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>
|
|
|
|
<variablelist class='journal-directives'>
|
|
<varlistentry>
|
|
<term><varname>__CURSOR=</varname></term>
|
|
<listitem>
|
|
<para>The cursor for the entry. A cursor is an opaque text
|
|
string that uniquely describes the position of an entry in
|
|
the journal and is portable across machines, platforms and
|
|
journal files.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>__REALTIME_TIMESTAMP=</varname></term>
|
|
<listitem>
|
|
<para>The wallclock time
|
|
(<constant>CLOCK_REALTIME</constant>) at the point in time
|
|
the entry was received by the journal, in microseconds since
|
|
the epoch UTC, formatted as a decimal string. This has
|
|
different properties from
|
|
<literal>_SOURCE_REALTIME_TIMESTAMP=</literal>, as it is
|
|
usually a bit later but more likely to be monotonic.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>__MONOTONIC_TIMESTAMP=</varname></term>
|
|
<listitem>
|
|
<para>The monotonic time
|
|
(<constant>CLOCK_MONOTONIC</constant>) at the point in time
|
|
the entry was received by the journal in microseconds,
|
|
formatted as a decimal string. To be useful as an address
|
|
for the entry, this should be combined with the boot ID in
|
|
<literal>_BOOT_ID=</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
<para>
|
|
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|