[Logback SiftingAppender with Marker] #logback #spring

Demo.java

// Will be written to `log/yyyy-MM-dd/demo.log`
Marker marker = MarkerFactory.getMarker("demo");
log.info(marker, "hello world");

logback-spring.xml

<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 class="com.example.discriminator.MarkerDiscriminator">
        </discriminator>
        <sift>
            <appender name="FILE-${filename}" class="ch.qos.logback.core.FileAppender">
                <file>log/${filename}.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>

MarkerDiscriminator.java

public class MarkerDiscriminator extends AbstractDiscriminator<ILoggingEvent> {

    @Override
    public String getDiscriminatingValue(ILoggingEvent iLoggingEvent) {
        final Marker marker = iLoggingEvent.getMarker();
        return marker == null ? "spring" : (LocalDate.now().format(DateTimeFormatter.ISO_DATE) + "/" + marker);
    }

    @Override
    public String getKey() {
        return "filename";
    }

}