protected function getTagName($options) {
    if ($options['tag']) {
      $tag_name = $options['tag'];
    }
    else {
      $tag_name = $this->ask('Enter the tag name for the deployment artifact, e.g., 1.0.0-build');
    }

    if (empty($tag_name)) {
      // @todo Validate tag name is valid, e.g., no spaces or special characters.
      throw new BltException("You must enter a valid tag name.");
    }
    else {
      $this->say("Tag is set to <comment>$tag_name</comment>.");
    }

    return $tag_name;
  }