Get metrics for each application streaming statistics.

def _spark_streaming_statistics_metrics(self, instance, running_apps, addl_tags, requests_config):
        """
        Get metrics for each application streaming statistics.
        """
        for app_id, (app_name, tracking_url) in iteritems(running_apps):
            try:
                base_url = self._get_request_url(instance, tracking_url)
                response = self._rest_request_to_json(
                    base_url,
                    SPARK_APPS_PATH,
                    SPARK_SERVICE_CHECK,
                    requests_config,
                    addl_tags,
                    app_id,
                    'streaming/statistics',
                )
                self.log.debug('streaming/statistics: %s', response)
                tags = ['app_name:%s' % str(app_name)]
                tags.extend(addl_tags)

                # NOTE: response is a dict
                self._set_metrics_from_json(tags, response, SPARK_STREAMING_STATISTICS_METRICS)
            except HTTPError as e:
                # NOTE: If api call returns response 404
                # then it means that the application is not a streaming application, we should skip metric submission
                if e.response.status_code != 404:
                    raise