spring-cloud-starter-gateway 使用中 KafkaAppender的问题

公司需要将应用日志上报到kafka，以供分析与查看。

结合logback可以完成此功能，大致配置如下：

<appender name="KafkaAppender" class="com.github.danielwegener.logback.kafka.KafkaAppender">
        <encoder class="com.github.danielwegener.logback.kafka.encoding.LayoutKafkaMessageEncoder">
            <layout class="net.logstash.logback.layout.LogstashLayout" >
                <includeContext>true</includeContext>
                <includeCallerData>true</includeCallerData>
                <fieldNames class="net.logstash.logback.fieldnames.ShortenedFieldNames"/>
            </layout>
            <charset>UTF-8</charset>
        </encoder>
        <!--kafka topic 需要与配置文件里面的topic一致 否则kafka会沉默并鄙视你-->
        <topic>${topic}</topic>
        <keyingStrategy class="com.github.danielwegener.logback.kafka.keying.HostNameKeyingStrategy" />
        <deliveryStrategy class="com.github.danielwegener.logback.kafka.delivery.AsynchronousDeliveryStrategy" />
        <producerConfig>bootstrap.servers=${BOOT_SERVER}</producerConfig>
    </appender>

上述配置有个问题：
当kafka服务异常时，会阻塞业务系统请求。

此时，引入AsyncAppender可以处理上面的问题，让日志系统异步执行，当kafka出现问题时，不阻塞业务系统，大致配置如下：

<appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
        <appender-ref ref="KafkaAppender"/>
        <queueSize>1000</queueSize>
        <discardingThreshold>0</discardingThreshold>
        <!--这里一定要配置-->
        <neverBlock>true</neverBlock>
    </appender>

实际使用时，本地启动，一切正常，当将jar放到服务器上时，日志系统无法启动，最终导致服务启动失败，部分堆栈如下：

Caused by: java.lang.IllegalStateException: Logback configuration error detected: 
ERROR in com.github.danielwegener.logback.kafka.KafkaAppender[KafkaAppender] - Appender [KafkaAppender] failed to append. org.apache.kafka.common.errors.InterruptException: java.lang.InterruptedException
ERROR in com.github.danielwegener.logback.kafka.KafkaAppender[KafkaAppender] - Appender [KafkaAppender] failed to append. org.apache.kafka.common.errors.InterruptException: java.lang.InterruptedException
ERROR in com.github.danielwegener.logback.kafka.KafkaAppender[KafkaAppender] - Appender [KafkaAppender] failed to append. org.apache.kafka.common.errors.InterruptException: java.lang.InterruptedException
	at org.springframework.boot.logging.logback.LogbackLoggingSystem.loadConfiguration(LogbackLoggingSystem.java:169)
	at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:80)
	at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:60)
	at org.springframework.boot.logging.logback.LogbackLoggingSystem.initialize(LogbackLoggingSystem.java:118)
	at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:313)
	at org.springframework.boot.context.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:288)
	at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:246)
	at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:223)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)
	at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:76)
	at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:53)
	at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:345)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
	at cn.com.bdo.gateway.BizBdoGatewayApplication.main(BizBdoGatewayApplication.java:16)

经过不断尝试，日志系统添加以下配置即可处理上述问题：

<logger name="org.springframework.boot.context.logging" level="DEBUG"/>

由于只有服务器上有问题，debug比较困难，所以没有继续分析原因。

特此记录。