log4j2-extended-jsonlayout

Customizable JSONLayout for Log4j2

• Fork of https://github.com/savantly-net/log4j2-extended-jsonlayout
• Since the original developer has not maintained the project (does not work with the current version of log4j2), I forked it and modified to serve me better.
• Additional json fields have access to original log message

Include the artifact

<dependency>
    <groupId>org.laurell.log4j2</groupId>
    <artifactId>extended-jsonlayout</artifactId>
    <version>1.0.4</version>
</dependency>

Example Usage

Inside your log4j2 configuration, you can configure the new pattern "ExtendedJsonLayout"

<Appenders>
    <Console name="STDOUT" target="SYSTEM_OUT">
        <ExtendedJsonLayout complete="false" properties="true"/>
    </Console>
</Appenders>
	

The default ExtendedJson implementation Produces output like below -

{
  "instant" : {
    "epochSecond" : 1556795579,
    "nanoOfSecond" : 277000000
  },
  "thread" : "main",
  "level" : "INFO",
  "loggerName" : "org.hibernate.validator.internal.xml.ValidationXmlParser",
  "message" : "HV000007: META-INF/validation.xml found. Parsing XML based configuration.",
  "endOfBatch" : false,
  "loggerFqcn" : "org.hibernate.validator.internal.util.logging.Log_$logger",
  "contextMap" : { },
  "threadId" : 1,
  "threadPriority" : 5,
  "hostname" : "MY-LAPTOP"
}

Add custom Json Fields

Implement the ExtendedJson interface
And configure the class name in your log configuration -

<ExtendedJsonLayout complete="false" properties="true" 
            jsonAdapterClassName="com.example.MyCustomJsonLogger">
</ExtendedJsonLayout>

Example Custom Implementation

package com.example;

import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.layout.ExtendedJson;

public class MyCustomJsonLogger implements ExtendedJson{
	
	HashMap<String, Object> mixedIn = new HashMap<>();
	Random r = new Random();
	
	public MyCustomJsonLogger() {
		mixedIn.put("myCustomKey", "myCustomValue");
		mixedIn.put("anotherKey", r.nextInt(200));
	}

	@Override
	public Map<String, Object> getMixedFields(LogEvent logEvent) {
		return mixedIn;
	}

}

Each item in the Map<String,Object> are added to the root logging message so that it appears like this -

{
  "instant" : {
      "epochSecond" : 1556795579,
      "nanoOfSecond" : 277000000
  },
  "thread" : "main",
  "level" : "INFO",
  "loggerName" : "org.springframework.data.repository.config.RepositoryConfigurationDelegate",
  "message" : "Multiple Spring Data modules found, entering strict repository configuration mode!",
  "endOfBatch" : false,
  "loggerFqcn" : "org.apache.logging.slf4j.Log4jLogger",
  "contextMap" : { },
  "threadId" : 1,
  "threadPriority" : 5,
  "anotherKey" : 36,
  "myCustomKey" : "myCustomValue"
}