Synchronised issue for log file between system and docker container

Question

I've added fileAppender for sending logs to file and mounted log file to docker container with docker-compose. The issue which I faced is logs between file from system and docker container are not synchronised before I manually change the system file(adding something and save).

Appender

<property name="LOGS_HOME" value="./docker-compose/logs" />
<appender name="FILE" class="ch.qos.logback.core.FileAppender">
        <file>${LOGS_HOME}/logs.log</file>
        <append>true</append>
        <immediateFlush>true</immediateFlush>
        <encoder charset="UTF-8" class="net.logstash.logback.encoder.LogstashEncoder"/>
    </appender>

Docker-compose mounting:

  promtail:
    image: grafana/promtail:2.2.1
    volumes:
      - type: bind
        source: ./docker-compose/logs/logs.log
        target: /var/logs/logs.log