code: public static String getImageIdFromAgent(Launcher launcher, final String imageTag, final String host) throws IOException, InterruptedException {
          return launcher.getChannel().call(new MasterToSlaveCallable<String, IOException>() {
              public String call() throws IOException {
                  return DockerUtils.getImageIdFromTag(imageTag, host);
              }
          });
      }
docs: Get image ID from imageTag on the current agent.
  
  @param imageTag
  @return