Log4j2: Property substitution works incorrectly for filePattern in RollingFile appender

Question

I am trying to configure RollingFile appender in tomcat 7.0.23 with log4j2(2.0.2) with 10 log files.

I am using in the filePattern the ${sys:catalina.base}, it doesn't work and log files are placed in tomcat/bin/${sys:catalina.base}/ directory.

The interesting part is that the first log file (without a number) is created ok, under tomcat/logs - which means it succeeds to map the filename attribute to a real path.

When I replace ${sys:catalina.base} with filePattern="C:/apache-tomcat-7.0.23/logs/app.%i.log" it works.

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
    <Appenders>
        <Console name="CONSOLE" target="SYSTEM_OUT">
            <PatternLayout pattern="%d %-5p [%X{REQ_ID}] [%c{1}] %m%n"/>
        </Console>
        <RollingFile name="FILE" fileName="${sys:catalina.base}/logs/app.log"
                     filePattern="${sys:catalina.base}/logs/app.%i.log">
            <PatternLayout pattern="%d %-5p [%X{REQ_ID}] [%c{1}] %m%n"/>
            <Policies>
                <SizeBasedTriggeringPolicy size="10 MB" />
            </Policies>
            <DefaultRolloverStrategy max="10"/>
        </RollingFile>
    </Appenders>
    <Loggers>
        <Root level="info">
            <appender-ref ref="CONSOLE" />
            <appender-ref ref="FILE" />
        </Root>
    </Loggers>
</Configuration>

Meaning that the filePattern is not interpreted properly.

How do I overcome this without having to specify the log directory statically?

Thanks for the help

Answer 1

What you describe looks very much like the issue reported in LOG4J2-829. This is a bug that was introduced in the 2.0-RC2 release. It was recently fixed in master and the fix will be included in the upcoming 2.1 release. (I hope 2.1 will be released some time next week - but no promises...)

If you are in a hurry, you can check out the code from the Log4j2 GIT repository and build the 2.1-SNAPSHOT locally.