SpringBoot项目使用logback自定义配置后，会在/tmp/ 目录下生成 spring.log的文件(如下图所示)。
解决方案
通过各种资料的搜索，最终发现问题的所在(logback配置如下)。
<?xml version="1.0" encoding="UTF-8"?>
<configuration scan="true">
<include resource="org/springframework/boot/logging/logback/base.xml"/>
<springProperty scope="context" source="spring.application.name"/>
<property value="logs/${springAppName}"/>
<appender>
<layout>
<pattern>
%black(%d{ISO8601}) %highlight(%-5level) [%blue(%t)] %yellow(%C{1.}): %msg%n%throwable
</pattern>
</layout>
</appender>
<appender>
<rollingPolicy>
<fileNamePattern>${LOG_FILE}.%d{yyyy-MM-dd}.%i.log</fileNamePattern>
<maxHistory>90</maxHistory>
<timeBasedFileNamingAndTriggeringPolicy>
<maxFileSize>200MB</maxFileSize>
</timeBasedFileNamingAndTriggeringPolicy>
</rollingPolicy>
<encoder>
<charset>utf-8</charset>
<pattern>%d %-5level [%thread] %logger{0}: %msg%n</pattern>
</encoder>
</appender>
<appender>
<queueSize>512</queueSize>
<appender-ref ref="FILE"/>
</appender>
<root level="DEBUG">
<appender-ref ref="CONSOLE"/>
<appender-ref ref="ASYNC"/>
</root>
<!-- https://logback.qos.ch/manual/configuration.html#shutdownHook and https://jira.qos.ch/browse/LOGBACK-1090 -->
<shutdownHook/>
<contextListener>
<resetJUL>true</resetJUL>
</contextListener>
</configuration>
通过分析上面配置发现base.xml中包含了以下内容:
<?xml version="1.0" encoding="UTF-8"?>
<!--
Base logback configuration provided for compatibility with Spring Boot 1.1
-->
<included>
<include resource="org/springframework/boot/logging/logback/defaults.xml" />
<property value="${LOG_FILE:-${LOG_PATH:-${LOG_TEMP:-${java.io.tmpdir:-/tmp}}/}spring.log}"/>
<include resource="org/springframework/boot/logging/logback/console-appender.xml" />
<include resource="org/springframework/boot/logging/logback/file-appender.xml" />
<root level="INFO">
<appender-ref ref="CONSOLE" />
<appender-ref ref="FILE" />
</root>
</included>
从base.xml中可以看出来，会在/tmp/目录下默认生成一个spring.log，问题已经发现了，那就说明这里的配置需要更改，改成什么呢？
通过在github上查询，只需要将
<include resource="org/springframework/boot/logging/logback/base.xml"/>
替换成
<include resource="org/springframework/boot/logging/logback/defaults.xml" />
即可。
