我正在尝试使用springcloudsleuth在我的kotlin应用程序中实现分布式跟踪。我要把这些数据发给数据狗。现在我可以跟踪我的日志，但我想添加一些额外的数据跨度。假设我想添加有关用户的信息，并能够在datadog中看到它。span标签对它有好处吗？我正在将json格式的日志发送到datadog，但是我不能在这里添加标记(traceid和spanid被注入）。logback配置：

<encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder">
            <providers>
                <timestamp/>
                <version/>
                <message/>
                <loggerName/>
                <threadName/>
                <logLevel/>
                <logLevelValue/>
                <callerData/>
                <stackTrace/>
                <rootStackTraceElement/>
                <context/>
                <mdc/>
                <tags/>
                <logstashMarkers/>
                <arguments/>
            </providers>
        </encoder>

grad尔：

implementation("org.jetbrains.kotlin:kotlin-reflect")
implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
implementation("org.springframework.cloud:spring-cloud-starter-netflix-eureka-server")
implementation("org.springframework.cloud:spring-cloud-starter-vault-config")
implementation("org.springframework.cloud:spring-cloud-starter-sleuth")
implementation("org.springframework.boot:spring-boot-starter-actuator")
implementation("ch.qos.logback:logback-classic:1.2.3")
implementation("net.logstash.logback:logstash-logback-encoder:6.6")
implementation("org.zalando:logbook-spring-boot-starter:2.4.2")
developmentOnly("org.springframework.boot:spring-boot-devtools")
runtimeOnly("io.micrometer:micrometer-registry-datadog")
testImplementation("org.springframework.boot:spring-boot-starter-test")

加上标签我正在努力

@NewSpan
fun newSpanTest() {
    tracer.currentSpan()!!.tag("user", "123")
    log.info("other span")
    otherTestService.sameSpanTest()
}

日志示例：

{"@timestamp":"2021-03-09T21:04:46.953+01:00","@version":"1","message":"other span","logger_name":"com.microservices.text.rpg.servicediscovery.TestService","thread_name":"http-nio-8761-exec-3","level":"INFO","level_value":20000,"caller_class_name":"com.microservices.text.rpg.servicediscovery.TestService","caller_method_name":"newSpanTest","caller_file_name":"TestService.kt","caller_line_number":25,"traceId":"e61fd165d7c84776","spanId":"5e61f9b51b51619b"}

那个“用户”不应该先注入mdc，然后再注入日志吗？