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from airflow.sensors.base_sensor_operator import BaseSensorOperator
from airflow.utils import apply_defaults
from airflow.exceptions import AirflowException
[docs]class EmrBaseSensor(BaseSensorOperator):
"""
Contains general sensor behavior for EMR.
Subclasses should implement get_emr_response() and state_from_response() methods.
Subclasses should also implement NON_TERMINAL_STATES and FAILED_STATE constants.
"""
@apply_defaults
def __init__(
self,
aws_conn_id='aws_default',
*args, **kwargs):
super(EmrBaseSensor, self).__init__(*args, **kwargs)
self.aws_conn_id = aws_conn_id
[docs] def poke(self, context):
response = self.get_emr_response()
if not response['ResponseMetadata']['HTTPStatusCode'] == 200:
self.log.info('Bad HTTP response: %s', response)
return False
state = self.state_from_response(response)
self.log.info('Job flow currently %s', state)
if state in self.NON_TERMINAL_STATES:
return False
if state in self.FAILED_STATE:
final_message = 'EMR job failed'
failure_message = self.failure_message_from_response(response)
if failure_message:
final_message += ' ' + failure_message
raise AirflowException(final_message)
return True