log4j2 RollingFile Appender requires date pattern - log4j2

Question

I have defined a RollingFile Appender in log4j2
<RollingFile name="Locserver" append="true" fileName="locserver.log" filePattern="locserver-%i.log">
<PatternLayout>
<pattern>%d{ISO8601} [%t] %p %c %L - %m%n</pattern>
</PatternLayout>
<Policies>
<SizeBasedTriggeringPolicy size="50 MB"></SizeBasedTriggeringPolicy>
<DefaultRolloverStrategy>10</DefaultRolloverStrategy>
</Policies>
</RollingFile>
However when I try to run this I get an error
IllegalStateException : Pattern does not contain a date at
org.apache.logging.log4j.core.appender.rolling.PatternProcessor.getNExtTime(PatternProcessor.java:91)
This goes away as soon as I put a date pattern in filePattern for example, locserver-%d{MM-dd-yyyy}-%i.log. But I dont want the date in the log names. Is a bug or something wrong with my config?

Answer 1

In RollingFile appender,TimeBasedTrigerringPolicy checks for datepattern in filepattern attribute of tag. Specifing datepattern is then mandatory when using TimeBasedTrigerringPolicy.
Place %d{...} containing a SimpleDate Pattern in filePattern, e.g.:
<Appenders>
<RollingFile name="RollingFile" fileName="logs/rpi_gpio_latest.log"
filePattern="logs/**%d{yyyy-MM-dd_HH}**_rpi_gpio_%i.log">
<PatternLayout>
<Pattern>%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n</Pattern>
</PatternLayout>
<Policies>
<TimeBasedTriggeringPolicy />
<SizeBasedTriggeringPolicy size="4 MB"/>
</Policies>
<DefaultRolloverStrategy fileIndex="max"/>
</RollingFile>
</Appenders>

Answer 2

Thanks Joe.
I finally figured it out.
I had an empty TimeBasedTriggeringPolicy tag within my Policies list which was forcing the date check in the filePattern. Once I removed it, it started working fine.

Answer 3

For me, that works like described here (using log4j 2.0-beta9 & Java 1.7).
My log4j.xml (size-policy set to 1kB just for testing):
<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
<Appenders>
<Console name="STDOUT" target="SYSTEM_OUT">
<PatternLayout pattern="%d %-5p [%t] %C{2} (%F:%L) - %m%n"/>
</Console>
<RollingFile name="Logfile"
fileName="Log/App.log"
filePattern="Log/App-%i.log">
<PatternLayout pattern="%d %-5p [%t] %C{2} (%F:%L) - %m%n"/>
<Policies>
<SizeBasedTriggeringPolicy size="1 KB"/>
</Policies>
<DefaultRolloverStrategy max="4"/>
</RollingFile>
</Appenders>
<Loggers>
<Root level="info">
<AppenderRef ref="STDOUT"/>
<AppenderRef ref="Logfile"/>
</Root>
</Loggers>
</Configuration>
And it also works when using your config fragment (I'd just corrected the DefaultRolloverStrategy-setting):
<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
<Appenders>
<Console name="STDOUT" target="SYSTEM_OUT">
<PatternLayout pattern="%d %-5p [%t] %C{2} (%F:%L) - %m%n"/>
</Console>
<RollingFile name="Locserver"
append="true"
fileName="locserver.log"
filePattern="locserver-%i.log">
<PatternLayout>
<pattern>%d{ISO8601} [%t] %p %c %L - %m%n</pattern>
</PatternLayout>
<Policies>
<SizeBasedTriggeringPolicy size="50 MB"></SizeBasedTriggeringPolicy>
</Policies>
<DefaultRolloverStrategy max="4"/>
</RollingFile>
</Appenders>
<Loggers>
<Logger name="eeo.tts" level="debug"/>
<Root level="info">
<AppenderRef ref="STDOUT"/>
<AppenderRef ref="Locserver"/>
</Root>
</Loggers>
</Configuration>
Which Version of log4j2 are you using?