How can I configure logback conf to send all messages to stderr?

Question

Recently added some println output to my program... and now dont want logback INFO messages merging with them. How can I get all messages to stderr ?

Answer 1

Create appender and attach all logs for it:

<appender name="STDERR" class="ch.qos.logback.core.ConsoleAppender">
    <target>System.err</target>
    <encoder>
        <pattern>%date [%thread] - 5level %logger{36} - %msg%n</pattern>
    </encoder>
</appender>

<logger name="org.apache" level="INFO ">
    <appender-ref ref="STDERR"/>
</logger>

All org.apache class logs(that uses slf4j) will be directed to System.err

Answer 2

Use a ConsoleAppender with the target attribute set to System.err. See http://logback.qos.ch/manual/appenders.html#ConsoleAppender for details.

Something like this in your logback.xml should work:

<configuration>
  <appender name="STDERR" class="ch.qos.logback.core.ConsoleAppender">
    <!-- encoders are assigned the type
         ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
    <target>System.err</target>
    <encoder>
      <pattern>%-4relative [%thread] %-5level %logger{35} - %msg %n</pattern>
    </encoder>
  </appender>

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