Filebeat unable to monitor container custom log path

Looks like you may be missing several critical line from the reference here

In src/main/resources/logback-spring.xml:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <property name="LOG_FILE" value="${LOG_FILE:-${LOG_PATH:-${LOG_TEMP:-${java.io.tmpdir:-/tmp}}}/spring.log}"/>
    <include resource="org/springframework/boot/logging/logback/defaults.xml"/>
    <include resource="org/springframework/boot/logging/logback/console-appender.xml" />
    <include resource="org/springframework/boot/logging/logback/file-appender.xml" />
    <!---- MISSING --->
    <include resource="co/elastic/logging/logback/boot/ecs-console-appender.xml" />
    <include resource="co/elastic/logging/logback/boot/ecs-file-appender.xml" />
    <root level="INFO">
        <!--- MISSING -->
        <appender-ref ref="ECS_JSON_CONSOLE"/> 
        <appender-ref ref="CONSOLE"/>
        <appender-ref ref="ECS_JSON_FILE"/>
        <appender-ref ref="FILE"/>
    </root>
</configuration>