Skip to content

how to log only one level with log4j2?

I’m using log4j2 in my application.

What I want is everything up to ‘debug’ to go to console, everything up to ‘info’ to go to myapp.log, and ONLY ‘info’ to go to ‘myapp-audit.log’.

The reason is, INFO mostly consists of successful modifications to data (ex. ‘user created’, ‘user updated’, ‘user deleted’, and so on). If is effectively an audit log of data modifications.

But I can’t get figure out how to do it.

How do I get ONLY ‘info’ to get logged to ‘myapp-audit.log’? Here’s my current configuration …

<?xml version="1.0" encoding="UTF-8"?>
<configuration status="WARN">
    <appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
        </Console>

        <File name="LogFile" fileName="myapp.log">
            <PatternLayout
                pattern="%d{yyyy-mm-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
        </File>

        <File name="AuditFile" fileName="myapp-audit.log">
            <PatternLayout
                pattern="%d{yyyy-mm-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
        </File>
    </appenders>

    <loggers>
        <root level="debug">
            <appender-ref ref="Console" level="debug" />
            <appender-ref ref="LogFile" level="info" />
            <appender-ref ref="AuditFile" level="info" /> <!-- I want ONLY 'info' here -->
        </root>
    </loggers>
</configuration>

Answer

If you specify INFO in the appender-ref, the appender will receive INFO, WARN, ERROR and FATAL events. You can further restrict to only INFO by filtering out WARN, ERROR and FATAL level events:

<File name="AuditFile" fileName="myapp-audit.log">
    <PatternLayout 
       pattern="%d{yyyy-mm-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%nZ" />
    <Filters>

        <!-- First deny warn, error and fatal messages -->
        <ThresholdFilter level="warn"  onMatch="DENY" onMismatch="NEUTRAL"/>
        <ThresholdFilter level="error" onMatch="DENY" onMismatch="NEUTRAL"/>
        <ThresholdFilter level="fatal" onMatch="DENY" onMismatch="NEUTRAL"/>

        <!-- Then accept info, warn, error, fatal and deny debug/trace -->
        <ThresholdFilter level="info"  onMatch="ACCEPT" onMismatch="DENY"/>
    </Filters>
</File>