Log Message Normalization Module (mmnormalize)ΒΆ

Module Name:    mmnormalize

Available since: 6.1.2+

Author: Rainer Gerhards <rgerhards@adiscon.com>


This module provides the capability to normalize log messages via liblognorm. Thanks to liblognorm, unstructured text, like usually found in log messages, can very quickly be parsed and put into a normal form. This is done so quickly, that it should be possible to normalize events in realtime.

This module is implemented via the output module interface. This means that mmnormalize should be called just like an action. After it has been called, the normalized message properties are available and can be accessed. These properties are called the “CEE/lumberjack” properties, because liblognorm creates a format that is inspired by the CEE/lumberjack approach.

Please note: CEE/lumberjack properties are different from regular properties. They have always “$!” prepended to the property name given in the rulebase. Such a property needs to be called with %$!propertyname%.

Note that mmnormalize should only be called once on each message. Behaviour is undefined if multiple calls to mmnormalize happen for the same message.

Module Parameters

  • allow_regex [boolean] defaults to “off” Specifies if regex field-type should be allowed. Regex field-type has significantly higher computational overhead compared to other fields, so it should be avoided when another field-type can achieve the desired effect. Needs to be “on” for regex field-type to work.

Action Parameters:

  • ruleBase [word] Specifies which rulebase file is to use. If there are multiple mmnormalize instances, each one can use a different file. However, a single instance can use only a single file. This parameter MUST be given, because normalization can only happen based on a rulebase. It is recommended that an absolute path name is given. Information on how to create the rulebase can be found in the liblognorm manual.
  • useRawMsg [boolean] Specifies if the raw message should be used for normalization (on) or just the MSG part of the message (off). Default is “off”.
  • path [word], defaults to “$!” Specifies the JSON path under which parsed elements should be placed. By default, all parsed properties are merged into root of message properties. You can place them under a subtree, instead. You can place them in local variables, also, by setting path=”$.”.
  • variable [word] (Available since: 8.5.1) Specifies if a variable insteed of property ‘msg’ should be used for normalization. A varible can be property, local variable, json-path etc. Please note that useRawMsg overrides this parameter, so if useRawMsg is set, variable will be ignored and raw message will be used.

Legacy Configuration Directives:

  • $mmnormalizeRuleBase <rulebase-file> - equivalent to the “ruleBase” parameter.
  • $mmnormalizeUseRawMsg <on/off> - equivalent to the “useRawMsg” parameter.

See Also

Caveats/Known Bugs:

None known at this time.


This activates the module and applies normalization to all messages:

action(type="mmnormalize" ruleBase="/path/to/rulebase.rb")

The same in legacy format:

$ModLoad mmnormalize
$mmnormalizeRuleBase /path/to/rulebase.rb
*.* :mmnormalize: