Rahman created LOG4J2-2772:
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Summary: KafkaAppender when used with FailoverAppender does not
work
Key: LOG4J2-2772
URL: https://issues.apache.org/jira/browse/LOG4J2-2772
Project: Log4j 2
Issue Type: Bug
Components: Appenders
Affects Versions: 2.12.1
Reporter: Rahman
I applied a KafkaAppender to the FailoverAppender and configured a
RollingFileAppender as one of the failoverAppenders. I used log4j 2.12.0
version. I deliberately switched off the kafka server and found that it does
not switch to the secondary RollingFileAppender. Below is the snapshot of the
configuration used.
{code:java}
// code placeholder
<Failover name="LOG_FAILOVER" primary="LOG_KAFKA">
<Failovers>
<AppenderRef ref="LOG_KAFKA_FAILOVER_APPENDER"/>
</Failovers>
</Failover>
<Kafka name="LOG_KAFKA" topic="${log.kafka.message.batch.cache.topic}"
ignoreExceptions="false">
<JsonLayout compact="false" eventEol="true" properties="true"/>
<Property name="bootstrap.servers" value="${log.kafka.bootstrap.servers}"/>
<Property name="zookeeper.connect" value="${log.kafka.zookeeper.connect}"/>
</KafkaFix>
<RollingFile name="LOG_KAFKA_FAILOVER_APPENDER"
fileName="${log.directory}/MessageBatchCacheKafkaFailOver.log"
filePattern="${log.directory}/MessageBatchCacheKafkaFailOver.log.%d{yyyy-MM-dd}.gz">
<JsonLayout compact="false" eventEol="true" properties="true"/>
<Policies>
<TimeBasedTriggeringPolicy interval="1" modulate="true" />
</Policies>
</RollingFile>
{code}
Upon looking for issues I found a fix for
https://issues.apache.org/jira/browse/LOG4J2-1103. But this issue did not
resolve the problem. Upon looking at the source code I modified the following
append method
{code:java}
// code placeholder
@Override
public void append(final LogEvent event) {
if (event.getLoggerName() != null &&
event.getLoggerName().startsWith("org.apache.kafka")) {
LOGGER.warn("Recursive logging from [{}] for appender [{}].",
event.getLoggerName(), getName());
} else {
try {
tryAppend(event);
} catch (final Exception e) {
if (ignoreExceptions()){
error("Unable to write to Kafka in appender [" + getName()
+ "]", event, e);
} else {
throw new AppenderLoggingException("Unable to write to
Kafka in appender [" + getName() + "]", e);
}
}
}
}
{code}
with the additions of the following lines in the catch statement.
{code:java}
// code placeholder
if (ignoreExceptions()){ error("Unable to write to Kafka in appender [" +
getName() + "]", event, e); } else { throw new AppenderLoggingException("Unable
to write to Kafka in appender [" + getName() + "]", e); }
{code}
As the FailoverAppender requires AppenderLoggingException for it to switch to
other secondary Appender, I found that in this method we were simply logging
the exception.
Kindly review the bug and let us know if there is an alternative solution than
the above.
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