For anyone ending up here after a google search: Log currently is broken in jmxtrans because of conflicting dependencies of slf4j,log4j and logback in jmxtrans.
https://github.com/jmxtrans/jmxtrans/issues/215
One way to fix this is to insert a logback.xml file into the root of the jmxtrans jar file:
<property name="logs-folder" value="${catalina.base}/logs"/>
<appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>${jmxtrans.log.dir}/jmxtrans.log</file>
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<!-- daily rollover -->
<fileNamePattern>${jmxtrans.log.dir}/jmxtrans_%d{yyyy-MM-dd}.%i.log</fileNamePattern>
<timeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
<!-- or whenever the file size reaches 300MB -->
<maxFileSize>300MB</maxFileSize>
</timeBasedFileNamingAndTriggeringPolicy>
<!-- keep 30 days' worth of history -->
<maxHistory>30</maxHistory>
</rollingPolicy>
<encoder>
<pattern>%date %level [%thread] %logger{36} [%file:%line] %msg%n</pattern>
</encoder>
</appender>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<layout class="ch.qos.logback.classic.PatternLayout">
<Pattern>%date %-5level [%thread] %-36logger{36} [%file:%line][%method] %msg%n</Pattern>
</layout>
</appender>
<logger name="com.googlecode.jmxtrans" level="${jmxtrans.log.level}"/>
<logger name="org.quartz" level="WARN"/>
<root level="DEBUG">
<appender-ref ref="FILE"/>
<appender-ref ref="STDOUT"/>
</root>
Note that I added a rolling policy to the log (You can remove it and use the Linux logrotate utility instead).