def verify_host(self, name, required):
    """Verify value of variable |name| is a valid hostname.

    Args:
      name [string]: variable name.
      required [bool]: If True, the value of variable |name| cannot be empty.
    """
    try:
      value = self.__bindings.get(name)
    except __HOLE__:
      if not required:
        return True
      self.__errors.append('Missing "{name}".'.format(name=name))
      return False
      
    if self.is_reference(value):
      if not required:
        return True
      self.__errors.append('Missing "{name}".'.format(name=name))
      return False

    host_token = _host_regex_token()
    host_regex = '^({host})$'.format(host=host_token)

    if not value:
      if not required:
        return True
      else:
        self.__errors.append(
            'No host provided for "{name}".'.format(name=name))
        return False

    if re.match(host_regex, value):
      return True

    self.__errors.append(
       'name="{value}" does not look like {regex}'.format(
         value=value, regex=host_regex))
    return False
dataset/ETHPy150Open spinnaker/spinnaker/pylib/spinnaker/validate_configuration.py/ValidateConfig.verify_host