Can someone help me understand why Log4j messages meant to get logged in syslog sometimes won't appear until I restart the rsyslog daemon?
On Ubuntu I've got a Java project setup to use Log4j2. I am using Log4j's SyslogAppender to log messages to rsyslog.
When I reference the SyslogAppender in the Root logger inside the log4j2.xml file, my messages get logged to /var/log/syslog every time.
When I reference the SyslogAppender in a logger for a Java object that I created (and remove the reference from the root logger), I see the following behavior every time:
1. Start Java program (log messages)
2. Verify message gets logged to /var/log/syslog (this step is successful)
3. Stop Java program
4. Restart Java program (log messages)
5. Verify messages get logged to /var/log/syslog (step fails)
6. Restart rsyslog: sudo service rsyslog restart
7. The expected message from step-5 then appears in /var/log/syslog
At step 5, I've waited up to 10 minutes. These steps happen like this no matter how long I wait.
Here is my log4j2.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="INFO">
<Appenders>
<Syslog name="bsd" host="localhost" port="514" protocol="UDP" facility="SYSLOG"/>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
</Console>
</Appenders>
<Loggers>
<Logger name="com.test.SyslogMgr" level="all">
<AppenderRef ref="bsd"/>
</Logger>
<Root level="error">
<!--If I leave this ref to "bsd" in and remove the ref in SyslogMgr, logs always appear.-->
<!--If I remove this "bsd" ref and leave SyslogMgr's in, I get the behavior described above -->
<AppenderRef ref="bsd"/>
<AppenderRef ref="Console" />
</Root>
</Loggers>
</Configuration>
Here is my Java Class:
public class SyslogMgr {
private static final org.apache.logging.log4j.Logger logger = LogManager.getLogger(SyslogMgr.class);
public void addToSyslog(String msg) {
logger.info(msg);
}
}