Multiline codec plugin

• Plugin version: v3.1.2
• Released on: 2024-04-25
• Changelog

For other versions, see the Versioned plugin docs.

For questions about the plugin, open a topic in the Discuss forums. For bugs or feature requests, open an issue in Github. For the list of Elastic supported plugins, please consult the Elastic Support Matrix.

The multiline codec will collapse multiline messages and merge them into a single event.

The original goal of this codec was to allow joining of multiline messages from files into a single event. For example, joining Java exception and stacktrace messages into a single event.

The config looks like this:

input {
  stdin {
    codec => multiline {
      pattern => "pattern, a regexp"
      negate => "true" or "false"
      what => "previous" or "next"
    }
  }
}

The pattern should match what you believe to be an indicator that the field is part of a multi-line event.

The what must be previous or next and indicates the relation to the multi-line event.

The negate can be true or false (defaults to false). If true, a message not matching the pattern will constitute a match of the multiline filter and the what will be applied. (vice-versa is also true)

For example, Java stack traces are multiline and usually have the message starting at the far-left, with each subsequent line indented. Do this:

input {
  stdin {
    codec => multiline {
      pattern => "^\s"
      what => "previous"
    }
  }
}

This says that any line starting with whitespace belongs to the previous line.

Another example is to merge lines not starting with a date up to the previous line..

input {
  file {
    path => "/var/log/someapp.log"
    codec => multiline {
      # Grok pattern names are valid! :)
      pattern => "^%{TIMESTAMP_ISO8601} "
      negate => true
      what => "previous"
    }
  }
}

This says that any line not starting with a timestamp should be merged with the previous line.

One more common example is C line continuations (backslash). Here’s how to do that:

input {
  stdin {
    codec => multiline {
      pattern => "\\$"
      what => "next"
    }
  }
}

This says that any line ending with a backslash should be combined with the following line.

• Value type is number
• There is no default value for this setting.

The accumulation of multiple lines will be converted to an event when either a matching new line is seen or there has been no new data appended for this many seconds. No default. If unset, no auto_flush. Units: seconds

• Value can be any of: ASCII-8BIT, UTF-8, US-ASCII, Big5, Big5-HKSCS, Big5-UAO, CP949, Emacs-Mule, EUC-JP, EUC-KR, EUC-TW, GB2312, GB18030, GBK, ISO-8859-1, ISO-8859-2, ISO-8859-3, ISO-8859-4, ISO-8859-5, ISO-8859-6, ISO-8859-7, ISO-8859-8, ISO-8859-9, ISO-8859-10, ISO-8859-11, ISO-8859-13, ISO-8859-14, ISO-8859-15, ISO-8859-16, KOI8-R, KOI8-U, Shift_JIS, UTF-16BE, UTF-16LE, UTF-32BE, UTF-32LE, Windows-31J, Windows-1250, Windows-1251, Windows-1252, IBM437, IBM737, IBM775, CP850, IBM852, CP852, IBM855, CP855, IBM857, IBM860, IBM861, IBM862, IBM863, IBM864, IBM865, IBM866, IBM869, Windows-1258, GB1988, macCentEuro, macCroatian, macCyrillic, macGreek, macIceland, macRoman, macRomania, macThai, macTurkish, macUkraine, CP950, CP951, IBM037, stateless-ISO-2022-JP, eucJP-ms, CP51932, EUC-JIS-2004, GB12345, ISO-2022-JP, ISO-2022-JP-2, CP50220, CP50221, Windows-1256, Windows-1253, Windows-1255, Windows-1254, TIS-620, Windows-874, Windows-1257, MacJapanese, UTF-7, UTF8-MAC, UTF-16, UTF-32, UTF8-DoCoMo, SJIS-DoCoMo, UTF8-KDDI, SJIS-KDDI, ISO-2022-JP-KDDI, stateless-ISO-2022-JP-KDDI, UTF8-SoftBank, SJIS-SoftBank, BINARY, CP437, CP737, CP775, IBM850, CP857, CP860, CP861, CP862, CP863, CP864, CP865, CP866, CP869, CP1258, Big5-HKSCS:2008, ebcdic-cp-us, eucJP, euc-jp-ms, EUC-JISX0213, eucKR, eucTW, EUC-CN, eucCN, CP936, ISO2022-JP, ISO2022-JP2, ISO8859-1, ISO8859-2, ISO8859-3, ISO8859-4, ISO8859-5, ISO8859-6, CP1256, ISO8859-7, CP1253, ISO8859-8, CP1255, ISO8859-9, CP1254, ISO8859-10, ISO8859-11, CP874, ISO8859-13, CP1257, ISO8859-14, ISO8859-15, ISO8859-16, CP878, MacJapan, ASCII, ANSI_X3.4-1968, 646, CP65000, CP65001, UTF-8-MAC, UTF-8-HFS, UCS-2BE, UCS-4BE, UCS-4LE, CP932, csWindows31J, SJIS, PCK, CP1250, CP1251, CP1252, external, locale
• Default value is "UTF-8"

The character encoding used in this input. Examples include UTF-8 and cp1252

This setting is useful if your log files are in Latin-1 (aka cp1252) or in another character set other than UTF-8.

This only affects "plain" format logs since JSON is UTF-8 already.

• Value type is string

• Supported values are:

  • disabled: plugin only sets the message field
  • v1,v8: Elastic Common Schema compliant behavior ([event][original] is also added)

• Default value depends on which version of Logstash is running:

  • When Logstash provides a pipeline.ecs_compatibility setting, its value is used as the default
  • Otherwise, the default value is disabled

Controls this plugin’s compatibility with the Elastic Common Schema (ECS).

• Value type is bytes
• Default value is "10 MiB"

The accumulation of events can make logstash exit with an out of memory error if event boundaries are not correctly defined. This settings make sure to flush multiline events after reaching a number of bytes, it is used in combination max_lines.

• Value type is number
• Default value is 500

The accumulation of events can make logstash exit with an out of memory error if event boundaries are not correctly defined. This settings make sure to flush multiline events after reaching a number of lines, it is used in combination max_bytes.

• Value type is string
• Default value is "multiline"

Tag multiline events with a given tag. This tag will only be added to events that actually have multiple lines in them.

• Value type is boolean
• Default value is false

Negate the regexp pattern (if not matched).

• This is a required setting.
• Value type is string
• There is no default value for this setting.

The regular expression to match.

• Value type is array
• Default value is []

Logstash ships by default with a bunch of patterns, so you don’t necessarily need to define this yourself unless you are adding additional patterns.

Pattern files are plain text with format:

NAME PATTERN

For example:

NUMBER \d+

• This is a required setting.
• Value can be any of: previous, next
• There is no default value for this setting.

If the pattern matched, does event belong to the next or previous event?