Logstash json_event pattern for log4j - groovy edition

What is it?

The original library has a few drawbacks when used in grails/groovy projects:

• file name, line number, class name & method name are wrong. This is a known issue in log4j appenders.
• external json library is obsolete due to groovy JsonBuilder.

Main differences compared to the original code are:

• outputs correct location information (thanks to this post)
• renamed the appender to JSONGroovyEventLayout to avoid any conflicts
• MDC key/value pairs are added directly to @fields
• v1 version removed

Implementation changes:

• switched from an external json library to JsonBuilder
• made the code more groovy...
• gradle instead of maven

Grails Usage

Complete documentation is provided by original library To use this library inside a grails project:

1. Build this library (gradle build) and move the produced jar file to the lib folder

2. Define the appender inside Config.groovy:

   log4j = {
   	appenders {
   		...
   		rollingFile name: "logstash", maxFileSize: '100MB', file: "logstash.log", layout: (new net.logstash.log4j.JSONGroovyEventLayout())
   		...
   	}
   	//don't forget to use the new appender
   

Sample logstash config:

input {
  file {
    path => ["C:/workspace/planG/logstash.log" ]
	codec =>   json {
	}
  }
}