Instrumenting Log4j

The metrics-log4j module provides InstrumentedAppender, a Log4j Appender implementation which records the rate of logged events by their logging level.

You can either add it to the root logger programmatically:

LogManager.getRootLogger().addAppender(new InstrumentedAppender());

Or you can add it via Log4j’s XML configuration:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    <appender name="console" class="org.apache.log4j.ConsoleAppender">
        <param name="Target" value="System.out"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%-5p %c{1} - %m%n"/>
        </layout>
    </appender>

    <appender name="metrics" class="com.yammer.metrics.log4j.InstrumentedAppender"/>

    <root>
        <priority value="debug"/>
        <appender-ref ref="console"/>
        <appender-ref ref="metrics"/>
    </root>
</log4j:configuration>