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What is GELFJ

It's very simple GELF implementation in pure Java with the log4j appender. It supports chunked messages which allows you to send large log messages (stacktraces, environment variables, additional fields, etc.) to Graylog2 Server.

How to use GELFJ

Grab latest JAR from the downloads section and drop it into your classpath.

Examples

To send a GELF message:

GelfMessage message = new GelfMessage("Short message", "Long message", new Date().getTime()/1000L, "1");
GelfSender gelfSender = new GelfSender("localhost", 12201);
if (message.isValid()) {
   gelfSender.sendMessage(message)
}

To send a GELF message with additional fields:

GelfMessage message = new GelfMessage("Short message", "Long message", new Date().getTime()/1000L, "1");
Map<String,Object> additonalFields = message.getAdditonalFields();
additonalFields.put("cat", "LOLCAT");
additonalFields.put("quote", "Can I haz cheezburger?");
GelfSender gelfSender = new GelfSender("localhost", 12201);
if (message.isValid()) {
   gelfSender.sendMessage(message)
}

Log4j appender

GELF log for4j appender will use log message as a short message and a stacktrace (if exception available) as a long message.

To use GELF Facility as appender in Log4J (XML format):

<appender name="graylog" class="org.graylog2.log.GelfAppender">
    <param name="graylogHost" value="192.168.0.201"/>
    <param name="Threshold" value="INFO"/>
    <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="%d |%t|%c{2}| %-5p - %m%n"/>
    </layout>
</appender>

and then add it as a one of appenders:

<root>
    <priority value="INFO"/>
    <appender-ref ref="graylog"/>
</root>    

What is GELF

The Graylog Extended Log Format (GELF) avoids the shortcomings of classic plain syslog:

• Limited to length of 1024 byte
• Not much space for payloads like backtraces
• Unstructured. You can only build a long message string and define priority, severity etc.

You can get more information here: http://www.graylog2.org/about/gelf