Log4j2: FailoverAppender

By using FailoverAppender, you can achieve failover mechanism, The FailoverAppender wraps a set of appenders, if the primary appender failed, then the secondary will be tried and so on.

Following table shows parameters of FailoverAppender.

Parameter	Type	Description
filter	Filter	Filters are used to filter the log events. Filters take the decision, whether to log the event (or) not. More than one Filter may be used by using a CompositeFilter.
primary	String	Name of the primary appender to use.
failovers	String[]	Names of the secondary appenders to use.
name	String	Name of the appender
retryIntervalSeconds	integer	The number of seconds that should pass before retrying the primary Appender. The default is 60 seconds.
ignoreExceptions	boolean	If ignoreExceptions set to false exceptions will be propagated to the caller. If ignoreExceptions is set to true, exceptions encountered while appending events to be internally logged and then ignored. Default value is true.
target	String	Either "SYSTEM_OUT" or "SYSTEM_ERR". Default value is SYSTEM_ERR.

log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="DEBUG" monitorInterval="30">
 <Appenders>
  <Console name="my_console_appender" target="SYSTEM_OUT">
   <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
  </Console>
  <File name="my_file_appender" fileName="/Users/harikrishna_gurram/application.log">
   <PatternLayout>
    <Pattern>%d %p %c{1.} [%t] %m%n</Pattern>
   </PatternLayout>
  </File>

  <Failover name="failover_appender" primary="my_file_appender">
   <Failovers>
    <AppenderRef ref="my_console_appender" />
   </Failovers>
  </Failover>
 </Appenders>
 <Loggers>
  <Root level="info">
   <AppenderRef ref="failover_appender" />
  </Root>
 </Loggers>
</Configuration>

package log4j_tutorial;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class HelloWorld {
 private static final Logger logger = LogManager.getLogger();

 public static void main(String args[]) throws InterruptedException {
  logger.trace("Trace Message!");
  Thread.sleep(20000);
  logger.debug("Debug Message!");
  logger.info("Info Message!");
  logger.warn("Warn Message!");
  logger.error("Error Message!");
  logger.fatal("Fatal Message!");
 }
}

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