JarCastinglog4j2-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"
}