Class InstanceMetadataRegionFetcher

awscli/utils.py:165–209

class InstanceMetadataRegionFetcher(IMDSFetcher):
    _URL_PATH = 'latest/meta-data/placement/availability-zone/'

    def retrieve_region(self):
        """Get the current region from the instance metadata service.

        :rvalue: str
        :returns: The region the current instance is running in or None
            if the instance metadata service cannot be contacted or does not
            give a valid response.

        :rtype: None or str
        :returns: Returns the region as a string if it is configured to use
            IMDS as a region source. Otherwise returns ``None``. It will also
            return ``None`` if it fails to get the region from IMDS due to
            exhausting its retries or not being able to connect.
        """
        try:
            region = self._get_region()
            return region
        except self._RETRIES_EXCEEDED_ERROR_CLS:
            logger.debug(
                "Max number of attempts exceeded (%s) when "
                "attempting to retrieve data from metadata service.",
                self._num_attempts,
            )
        except BadIMDSRequestError as e:
            logger.debug(
                "Failed to retrieve a region from IMDS. "
                "Region detection may not be supported from this endpoint: "
                "%s",
                e.request.url,
            )
        return None

    def _get_region(self):
        token = self._fetch_metadata_token()
        response = self._get_request(
            url_path=self._URL_PATH,
            retry_func=self._default_retry,
            token=token,
        )
        availability_zone = response.text
        region = availability_zone[:-1]
        return region


def split_on_commas(value):