title: When running sonarqube java dockerised app it get error sonarqube url not reachable
body: <p>I am running sonarqube from docker and it's working great for local projects, but when running it manually on a dockerized app it gives </p>
  
  <pre><code>[ERROR] SonarQube server [http://my-external-server-url:9000] can not be reached.
  </code></pre>
  
  <p>I ran it with maven in DEBUG mode and I got that </p>
  
  <pre><code>[ERROR] Failed to execute goal org.sonarsource.scanner.maven:sonar-maven-plugin:3.6.0.1398:sonar (default-cli) on project MY-PROJECT: Unable to execute SonarQube: Fail to get bootstrap index from server: No route to host (Host unreachable) -&gt; [Help 1]
  org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.sonarsource.scanner.maven:sonar-maven-plugin:3.6.0.1398:sonar (default-cli) on project MY-PROJECT: Unable to execute SonarQube
  </code></pre>
  
  <p>Am I missing something here ??
  P.S. It's a dockerized java project so I'm running from inside the docker, unlike other php projects</p>