title: Using external config in spring boot application within docker-compose
body: <p>I've got a spring boot application which uses <code>com.spotify.dockerfile-maven-plugin</code> to build a docker image of my application org.rtu/some-importer</p>
  
  <p>My docker-compose.yml is:</p>
  
  <pre><code>version: '3'
  services:
    some-importer:
      image: org.rtu/some-importer
      build: .
    zookeeper:
      image: wurstmeister/zookeeper
      ports:
        - "2181:2181"
    kafka: 
      image: wurstmeister/kafka
      ports:
        - "9092:9092"
      environment:
        KAFKA_ADVERTISED_HOST_NAME: 172.17.0.1
        KAFKA_CREATE_TOPICS: "test:1:1"
        KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
      volumes:
        - /var/run/docker.sock:/var/run/docker.sock
  </code></pre>
  
  <p>How can I say the during <code>docker-compose up</code> that it should be used an external <code>config.properties</code> from <code>/data/some-importer/config</code> folder?</p>