skywalking-java/docs/en/Application-toolkit-logback-1.x.md

• Dependency the toolkit, such as using maven or gradle

   <dependency>
      <groupId>org.apache.skywalking</groupId>
      <artifactId>skywalking-toolkit-logback-1.x</artifactId>
      <version>{project.release.version}</version>
   </dependency>

• set %tid in Pattern section of logback.xml

    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.TraceIdPatternLogbackLayout">
                <Pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%tid] [%thread] %-5level %logger{36} -%msg%n</Pattern>
            </layout>
        </encoder>
    </appender>

• When you use -javaagent to active the sky-walking tracer, logback will output traceId, if it existed. If the tracer is inactive, the output will be TID: N/A.