how to log only one level with log4j2?

Question

I\'m using log4j2 in my application.

What I want is everything up to \'debug\' to go to console, everything up to \'info\' to go to myapp.log, and ONLY \'info\' to g

Answer 1

If you specify INFO in the appender-ref, the appender will receive INFO, WARN, ERROR and FATAL events. You can further restrict to only INFO by filtering out WARN, ERROR and FATAL level events:

<File name="AuditFile" fileName="myapp-audit.log">
    <PatternLayout 
       pattern="%d{yyyy-mm-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%nZ" />
    <Filters>

        <!-- First deny warn, error and fatal messages -->
        <ThresholdFilter level="warn"  onMatch="DENY" onMismatch="NEUTRAL"/>
        <ThresholdFilter level="error" onMatch="DENY" onMismatch="NEUTRAL"/>
        <ThresholdFilter level="fatal" onMatch="DENY" onMismatch="NEUTRAL"/>

        <!-- Then accept info, warn, error, fatal and deny debug/trace -->
        <ThresholdFilter level="info"  onMatch="ACCEPT" onMismatch="DENY"/>
    </Filters>
</File>

Answer 2

You can't do that directly since the info level includes everything "above" - warn, error, fatal. What you can do is create a separate audit logger.

in the class:

Logger log = LogManager.getLogger("audit");

in the xml:

<Logger name="audit" level="info">
   <Appender-ref ref="AuditFile" level="info" />
</Logger>

Or you can use the RoutingAppender (you can use something other than ThreadContext):

ThreadContext.put("ROUTINGFLAG", "audit");
log.info("...");
ThreadContext.remove("ROUTINGFLAG");

in the xml:

...
    <Routing name="Routing">
        <Routes pattern="$${ctx:ROUTINGFLAG}">
            <Route AppenderRef="LogFile"/>              
            <Route AppenderRef="AuditFile" key="audit"/>                  
        </Routes>
    </Routing>
</Appenders>
<Loggers>
    <Root level="debug">
        <Appender-ref ref="Console" level="debug"/>
        <AppenderRef ref="Routing" level="info"/>
    </Root>
</Loggers>

Answer 3

You can use LevelRangeFilter. It has minLevel and maxLevel properties(and onMatch and onMismatch, ofcourse, too).

For example(in json) we need to print log in console only on info and warn levels:

"Appenders": {
  "Console": {
    "PatternLayout": {
      "pattern": "%d{yyyy-MMM-dd HH:mm:ss a} [%t] %-5level %logger{36} - %msg%n"
    },
    "name": "Console",
    "target": "SYSTEM_OUT",
    "LevelRangeFilter": {
      "minLevel": "warn",
      "maxLevel": "info",
      "onMatch": "ACCEPT",
      "onMismatch": "DENY"
    }
  }
}

And if you want only info level then write "info" to both properties min and max.