How can I configure Logback to log different levels for a logger to different destinations?

Question

How can I configure Logback to log different levels for a logger to different destinations?

For example, given the following Logback configuration, will Logback reco

Answer 1

No programming needed. configuration make your life easy.

Below is the configuration which logs different level of logs to different files

<property name="DEV_HOME" value="./logs" />

<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
        <level>INFO</level>
    </filter>
    <layout class="ch.qos.logback.classic.PatternLayout">
        <Pattern>
            %d{yyyy-MM-dd HH:mm:ss} %-5level - %msg%n
        </Pattern>
    </layout>
</appender>

<appender name="FILE-ERROR"
    class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>${DEV_HOME}/app-error.log</file>
    <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
        <Pattern>
            %d{yyyy-MM-dd HH:mm:ss} %-5level - %msg%n
        </Pattern>
    </encoder>

    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
        <!-- rollover daily -->
        <fileNamePattern>${DEV_HOME}/archived/app-error.%d{yyyy-MM-dd}.%i.log
        </fileNamePattern>
        <timeBasedFileNamingAndTriggeringPolicy
            class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
            <maxFileSize>10MB</maxFileSize>
        </timeBasedFileNamingAndTriggeringPolicy>
    </rollingPolicy>

    <filter class="ch.qos.logback.classic.filter.LevelFilter">
        <level>ERROR</level>
        <!--output messages of exact level only -->
        <onMatch>ACCEPT</onMatch>
        <onMismatch>DENY</onMismatch>
    </filter>
</appender>
<appender name="FILE-INFO"
    class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>${DEV_HOME}/app-info.log</file>
    <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
        <Pattern>
            %d{yyyy-MM-dd HH:mm:ss} %-5level - %msg%n
        </Pattern>
    </encoder>

    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
        <!-- rollover daily -->
        <fileNamePattern>${DEV_HOME}/archived/app-info.%d{yyyy-MM-dd}.%i.log
        </fileNamePattern>
        <timeBasedFileNamingAndTriggeringPolicy
            class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
            <maxFileSize>10MB</maxFileSize>
        </timeBasedFileNamingAndTriggeringPolicy>
    </rollingPolicy>


    <filter class="ch.qos.logback.classic.filter.LevelFilter">
        <level>INFO</level>
        <!--output messages of exact level only -->
        <onMatch>ACCEPT</onMatch>
        <onMismatch>DENY</onMismatch>
    </filter>
</appender>


<appender name="FILE-DEBUG"
    class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>${DEV_HOME}/app-debug.log</file>
    <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
        <Pattern>
            %d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n
        </Pattern>
    </encoder>

    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
        <!-- rollover daily -->
        <fileNamePattern>${DEV_HOME}/archived/app-debug.%d{yyyy-MM-dd}.%i.log
        </fileNamePattern>
        <timeBasedFileNamingAndTriggeringPolicy
            class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
            <maxFileSize>10MB</maxFileSize>
        </timeBasedFileNamingAndTriggeringPolicy>
    </rollingPolicy>

    <filter class="ch.qos.logback.classic.filter.LevelFilter">
        <level>DEBUG</level>
        <!--output messages of exact level only -->
        <onMatch>ACCEPT</onMatch>
        <onMismatch>DENY</onMismatch>
    </filter>
</appender>

<appender name="FILE-ALL"
    class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>${DEV_HOME}/app.log</file>
    <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
        <Pattern>
            %d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n
        </Pattern>
    </encoder>

    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
        <!-- rollover daily -->
        <fileNamePattern>${DEV_HOME}/archived/app.%d{yyyy-MM-dd}.%i.log
        </fileNamePattern>
        <timeBasedFileNamingAndTriggeringPolicy
            class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
            <maxFileSize>10MB</maxFileSize>
        </timeBasedFileNamingAndTriggeringPolicy>
    </rollingPolicy>
</appender>

<logger name="com.abc.xyz" level="DEBUG" additivity="true">
    <appender-ref ref="FILE-DEBUG" />
    <appender-ref ref="FILE-INFO" />
    <appender-ref ref="FILE-ERROR" />
    <appender-ref ref="FILE-ALL" />
</logger>

<root level="INFO">
    <appender-ref ref="STDOUT" />
</root>

Answer 2

I believe this would be the simplest solution:

<configuration>
    <contextName>selenium-plugin</contextName>
    <!-- Logging configuration -->  
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <Target>System.out</Target>
        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <level>INFO</level>
            <onMatch>ACCEPT</onMatch>
            <onMismatch>DENY</onMismatch>
        </filter>
        <encoder>
            <pattern>[%d{yyyy-MM-dd HH:mm:ss.SSS}] [%level] %msg%n</pattern>
        </encoder>
    </appender>
    <appender name="STDERR" class="ch.qos.logback.core.ConsoleAppender">
            <Target>System.err</Target>
        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <level>ERROR</level>
            <onMatch>ACCEPT</onMatch>
            <onMismatch>DENY</onMismatch>
        </filter>
        <encoder> 
            <pattern>[%d{yyyy-MM-dd HH:mm:ss.SSS}] [%level] [%thread] %logger{10} [%file:%line] %msg%n</pattern> 
        </encoder> 
    </appender>
    <root level="INFO">
        <appender-ref ref="STDOUT"/>
        <appender-ref ref="STDERR" />
    </root>
</configuration>

Answer 3

Update: For an all configuration based approach using Groovy see Dean Hiller's answer.

--

You can do some interesting things with Logback filters. The below configuration will only print warn and error messages to stderr, and everything else to stdout.

logback.xml

<appender name="stdout" class="ch.qos.logback.core.ConsoleAppender">
  <target>System.out</target>
  <filter class="com.foo.StdOutFilter" />
   ...
</appender>

<appender name="stderr" class="ch.qos.logback.core.ConsoleAppender">
  <target>System.err</target>
  <filter class="com.foo.ErrOutFilter" />
   ...
</appender>

<logger name="mylogger" level="debug">
    <appender-ref ref="stdout" />
    <appender-ref ref="stderr" />
</logger>

com.foo.StdOutFilter

public class StdOutFilter extends ch.qos.logback.core.filter.AbstractMatcherFilter
{

    @Override
    public FilterReply decide(Object event)
    {
        if (!isStarted())
        {
            return FilterReply.NEUTRAL;
        }

        LoggingEvent loggingEvent = (LoggingEvent) event;

        List<Level> eventsToKeep = Arrays.asList(Level.TRACE, Level.DEBUG, Level.INFO);
        if (eventsToKeep.contains(loggingEvent.getLevel()))
        {
            return FilterReply.NEUTRAL;
        }
        else
        {
            return FilterReply.DENY;
        }
    }

}

com.foo.ErrOutFilter

public class ErrOutFilter extends ch.qos.logback.core.filter.AbstractMatcherFilter
{

    @Override
    public FilterReply decide(Object event)
    {
        if (!isStarted())
        {
            return FilterReply.NEUTRAL;
        }

        LoggingEvent loggingEvent = (LoggingEvent) event;

        List<Level> eventsToKeep = Arrays.asList(Level.WARN, Level.ERROR);
        if (eventsToKeep.contains(loggingEvent.getLevel()))
        {
            return FilterReply.NEUTRAL;
        }
        else
        {
            return FilterReply.DENY;
        }
    }

}

Answer 4

I take no credit for this answer, as it's merely a combination of the best two answers above: that of X. Wo Satuk and that of Sébastien Helbert: ThresholdFilter is lovely but you can't configure it to have an upper level as well as a lower level*, but combining it with two LevelFilters set to "DENY" WARN and ERROR works a treat.

Very important: do not forget the <target>System.err</target> tag in the STDERR appender: my omission of it had me frustrated for a few minutes.

<configuration>
    <timestamp key="byDay" datePattern="yyyyMMdd'T'HHmmss" />
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
            <level>INFO</level>
        </filter>
        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <level>WARN</level>
            <onMatch>DENY</onMatch>
        </filter>
        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <level>ERROR</level>
            <onMatch>DENY</onMatch>
        </filter>
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36}.%M\(%line\)
                - %msg%n
            </pattern>
        </encoder>
    </appender>

    <appender name="STDERR" class="ch.qos.logback.core.ConsoleAppender">
        <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
            <level>WARN</level>
        </filter>
        <target>System.err</target>
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36}.%M\(%line\)
                - %msg%n
            </pattern>
        </encoder>
    </appender>

    <root level="debug">
        <appender-ref ref="STDOUT" />
        <appender-ref ref="STDERR" />
    </root>
</configuration>

* it does however have a method decide in the API but I haven't a clue how you'd use it in this context.

Answer 5

<configuration scan="true" scanPeriod="60 seconds">
 <appender name="A1" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>${storm.log.dir}/${logfile.name}</file>
    <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
      <fileNamePattern>${storm.log.dir}/${logfile.name}.%i</fileNamePattern>
      <minIndex>1</minIndex>
      <maxIndex>9</maxIndex>
    </rollingPolicy>

    <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
      <maxFileSize>100MB</maxFileSize>
    </triggeringPolicy>

    <encoder>
      <pattern>%d{yyyy-MM-dd'T'HH:mm:ss.SSSZZ} %c{1} [%p] %m%n</pattern>
    </encoder>
 </appender>

 <appender name="ACCESS" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>${storm.log.dir}/access.log</file>
    <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
      <fileNamePattern>${storm.log.dir}/access.log.%i</fileNamePattern>
      <minIndex>1</minIndex>
      <maxIndex>9</maxIndex>
    </rollingPolicy>

    <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
      <maxFileSize>100MB</maxFileSize>
    </triggeringPolicy>

    <encoder>
      <pattern>%d{yyyy-MM-dd'T'HH:mm:ss.SSSZZ} %c{1} [%p] %m%n</pattern>
    </encoder>
  </appender>

  <appender name="METRICS" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>${storm.log.dir}/metrics.log</file>
    <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
      <fileNamePattern>${storm.log.dir}/logs/metrics.log.%i</fileNamePattern>
      <minIndex>1</minIndex>
      <maxIndex>9</maxIndex>
    </rollingPolicy>

    <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
      <maxFileSize>2MB</maxFileSize>
    </triggeringPolicy>

    <encoder>
      <pattern>%d %-8r %m%n</pattern>
    </encoder>
  </appender>

  <root level="INFO">
    <appender-ref ref="A1"/>
  </root>

  <logger name="backtype.storm.security.auth.authorizer" additivity="false">
    <level value="INFO" />
    <appender-ref ref="ACCESS" />
  </logger>

  <logger name="backtype.storm.metric.LoggingMetricsConsumer" additivity="false" >
    <level value="INFO"/>
    <appender-ref ref="METRICS"/>
  </logger>

</configuration>

So here is the logback file in which I am not printing backtype.storm.metric.LoggingMetricsConsumer info level if i say additivity = "true" then for for all classes in backtype.* this rule will be applied

Answer 6

Try this. You can just use built-in ThresholdFilter and LevelFilter. No need to create your own filters programmically. In this example WARN and ERROR levels are logged to System.err and rest to System.out:

<appender name="stdout" class="ch.qos.logback.core.ConsoleAppender">
    <!-- deny ERROR level -->
    <filter class="ch.qos.logback.classic.filter.LevelFilter">
        <level>ERROR</level>
        <onMatch>DENY</onMatch>
    </filter>
    <!-- deny WARN level -->
    <filter class="ch.qos.logback.classic.filter.LevelFilter">
        <level>WARN</level>
        <onMatch>DENY</onMatch>
    </filter>
    <target>System.out</target>
    <immediateFlush>true</immediateFlush>
    <encoder>
        <charset>utf-8</charset>
        <pattern>${msg_pattern}</pattern>
    </encoder>
</appender>

<appender name="stderr" class="ch.qos.logback.core.ConsoleAppender">
    <!-- deny all events with a level below WARN, that is INFO, DEBUG and TRACE -->
    <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
        <level>WARN</level>
    </filter>
    <target>System.err</target>
    <immediateFlush>true</immediateFlush>
    <encoder>
        <charset>utf-8</charset>
        <pattern>${msg_pattern}</pattern>
    </encoder>
</appender>   

<root level="WARN">
    <appender-ref ref="stderr"/>
</root>

<root level="TRACE">
    <appender-ref ref="stdout"/>
</root>