<configuration>

    <appender name="SIFT" class="ch.qos.logback.classic.sift.SiftingAppender">
        <!-- in the absence of the class attribute, it is assumed that the
             desired discriminator type is
             ch.qos.logback.classic.sift.MDCBasedDiscriminator -->
        <discriminator>
            <key>taskId</key>
            <defaultValue>log</defaultValue>
        </discriminator>
        <sift>
            <appender name="FILE-${taskId}" class="ch.qos.logback.core.FileAppender">
                <file>log/${taskId}.log</file>
                <append>false</append>
                <layout class="ch.qos.logback.classic.PatternLayout">
                    <pattern>%d %marker [%thread] %level %mdc %logger{35} - %msg%n</pattern>
                </layout>
            </appender>
        </sift>
    </appender>

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