@Override
        public ConnectionParameter getConnectionParameter(String certPath) throws IOException {
            File unixSocket = new File("/var/run/docker.sock");
            if (unixSocket.exists() && unixSocket.canRead() && unixSocket.canWrite() && LocalSocketUtil.canConnectUnixSocket(unixSocket)) {
                return new ConnectionParameter("unix:///var/run/docker.sock", certPath);
            } else {
                return null;
            }
        }
Get the docker host url.
<ol>
  <li>From &lt;dockerHost&gt; configuration</li>
  <li>From &lt;machine&gt; configuration</li>
  <li>From DOCKER_HOST environment variable</li>
  <li>Default to /var/run/docker.sock</li>
</ol>
@param dockerHost The dockerHost configuration setting
@return The docker host url
@throws IOException when URL handling fails
src/main/java/io/fabric8/maven/docker/access/DockerConnectionDetector.java