title: How to combine Dockerfiles in gitlab ci?
body: <p>I have this gitlab-ci.yml to build my SpringBoot app:</p>
  
  <pre><code>image: maven:latest
  
  variables:
    MAVEN_CLI_OPTS: "-s .m2/settings.xml --batch-mode"
    MAVEN_OPTS: "-Dmaven.repo.local=.m2/repository"
  
  cache:
    paths:
      - .m2/repository/
      - target/
  
  build:
    stage: build
    script:
      - mvn $MAVEN_CLI_OPTS clean compile
    only:
      - /^release.*/
  
  test:
    stage: test
    script:
      - mvn $MAVEN_CLI_OPTS test
      - "cat target/site/coverage/jacoco-ut/index.html"
    only:
      - /^release.*/
  </code></pre>
  
  <p>Now, i need to run another JOB on the Test Stage: Integration Tests. My app runs the integration tests on Headless Chrome with an in memory database, all i need to do on windows is: <code>mvn integration-test</code></p>
  
  <p>I've found a Dockerfile that has the Headless Chrome ready, so i need to combine the maven:latest image with this new image <a href="https://hub.docker.com/r/justinribeiro/chrome-headless/" rel="nofollow noreferrer">https://hub.docker.com/r/justinribeiro/chrome-headless/</a></p>
  
  <p>How can i do that?</p>