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import os
from datetime import datetime
from airflow.contrib.hooks.gcs_hook import GoogleCloudStorageHook
from airflow.sensors.base_sensor_operator import BaseSensorOperator
from airflow.utils.decorators import apply_defaults
[docs]class GoogleCloudStorageObjectSensor(BaseSensorOperator):
"""
Checks for the existence of a file in Google Cloud Storage.
:param bucket: The Google cloud storage bucket where the object is.
:type bucket: str
:param object: The name of the object to check in the Google cloud
storage bucket.
:type object: str
:param google_cloud_conn_id: The connection ID to use when
connecting to Google cloud storage.
:type google_cloud_conn_id: str
:param delegate_to: The account to impersonate, if any.
For this to work, the service account making the request must have
domain-wide delegation enabled.
:type delegate_to: str
"""
[docs] template_fields = ('bucket', 'object')
@apply_defaults
def __init__(self,
bucket,
object, # pylint:disable=redefined-builtin
google_cloud_conn_id='google_cloud_default',
delegate_to=None,
*args, **kwargs):
super(GoogleCloudStorageObjectSensor, self).__init__(*args, **kwargs)
self.bucket = bucket
self.object = object
self.google_cloud_conn_id = google_cloud_conn_id
self.delegate_to = delegate_to
[docs] def poke(self, context):
self.log.info('Sensor checks existence of : %s, %s', self.bucket, self.object)
hook = GoogleCloudStorageHook(
google_cloud_storage_conn_id=self.google_cloud_conn_id,
delegate_to=self.delegate_to)
return hook.exists(self.bucket, self.object)
[docs]def ts_function(context):
"""
Default callback for the GoogleCloudStorageObjectUpdatedSensor. The default
behaviour is check for the object being updated after execution_date +
schedule_interval.
"""
return context['dag'].following_schedule(context['execution_date'])
[docs]class GoogleCloudStorageObjectUpdatedSensor(BaseSensorOperator):
"""
Checks if an object is updated in Google Cloud Storage.
:param bucket: The Google cloud storage bucket where the object is.
:type bucket: str
:param object: The name of the object to download in the Google cloud
storage bucket.
:type object: str
:param ts_func: Callback for defining the update condition. The default callback
returns execution_date + schedule_interval. The callback takes the context
as parameter.
:type ts_func: function
:param google_cloud_conn_id: The connection ID to use when
connecting to Google cloud storage.
:type google_cloud_conn_id: str
:param delegate_to: The account to impersonate, if any.
For this to work, the service account making the request must have domain-wide
delegation enabled.
:type delegate_to: str
"""
[docs] template_fields = ('bucket', 'object')
@apply_defaults
def __init__(self,
bucket,
object, # pylint:disable=redefined-builtin
ts_func=ts_function,
google_cloud_conn_id='google_cloud_default',
delegate_to=None,
*args, **kwargs):
super(GoogleCloudStorageObjectUpdatedSensor, self).__init__(*args, **kwargs)
self.bucket = bucket
self.object = object
self.ts_func = ts_func
self.google_cloud_conn_id = google_cloud_conn_id
self.delegate_to = delegate_to
[docs] def poke(self, context):
self.log.info('Sensor checks existence of : %s, %s', self.bucket, self.object)
hook = GoogleCloudStorageHook(
google_cloud_storage_conn_id=self.google_cloud_conn_id,
delegate_to=self.delegate_to)
return hook.is_updated_after(self.bucket, self.object, self.ts_func(context))
[docs]class GoogleCloudStoragePrefixSensor(BaseSensorOperator):
"""
Checks for the existence of a objects at prefix in Google Cloud Storage bucket.
:param bucket: The Google cloud storage bucket where the object is.
:type bucket: str
:param prefix: The name of the prefix to check in the Google cloud
storage bucket.
:type prefix: str
:param google_cloud_conn_id: The connection ID to use when
connecting to Google cloud storage.
:type google_cloud_conn_id: str
:param delegate_to: The account to impersonate, if any.
For this to work, the service account making the request must have
domain-wide delegation enabled.
:type delegate_to: str
"""
[docs] template_fields = ('bucket', 'prefix')
@apply_defaults
def __init__(self,
bucket,
prefix,
google_cloud_conn_id='google_cloud_default',
delegate_to=None,
*args, **kwargs):
super(GoogleCloudStoragePrefixSensor, self).__init__(*args, **kwargs)
self.bucket = bucket
self.prefix = prefix
self.google_cloud_conn_id = google_cloud_conn_id
self.delegate_to = delegate_to
[docs] def poke(self, context):
self.log.info('Sensor checks existence of objects: %s, %s',
self.bucket, self.prefix)
hook = GoogleCloudStorageHook(
google_cloud_storage_conn_id=self.google_cloud_conn_id,
delegate_to=self.delegate_to)
return bool(hook.list(self.bucket, prefix=self.prefix))
[docs]def get_time():
"""
This is just a wrapper of datetime.datetime.now to simplify mocking in the
unittests.
"""
return datetime.now()
[docs]class GoogleCloudStorageUploadSessionCompleteSensor(BaseSensorOperator):
"""
Checks for changes in the number of objects at prefix in Google Cloud Storage
bucket and returns True if the inactivity period has passed with no
increase in the number of objects. Note, it is recommended to use reschedule
mode if you expect this sensor to run for hours.
:param bucket: The Google cloud storage bucket where the objects are.
expected.
:type bucket: str
:param prefix: The name of the prefix to check in the Google cloud
storage bucket.
:param inactivity_period: The total seconds of inactivity to designate
an upload session is over. Note, this mechanism is not real time and
this operator may not return until a poke_interval after this period
has passed with no additional objects sensed.
:type inactivity_period: int
:param min_objects: The minimum number of objects needed for upload session
to be considered valid.
:type min_objects: int
:param previous_num_objects: The number of objects found during the last poke.
:type previous_num_objects: int
:param inactivity_seconds: The current seconds of the inactivity period.
:type inactivity_seconds: int
:param allow_delete: Should this sensor consider objects being deleted
between pokes valid behavior. If true a warning message will be logged
when this happens. If false an error will be raised.
:type allow_delete: bool
:param google_cloud_conn_id: The connection ID to use when connecting
to Google cloud storage.
:type google_cloud_conn_id: str
:param delegate_to: The account to impersonate, if any. For this to work,
the service account making the request must have domain-wide
delegation enabled.
:type delegate_to: str
"""
[docs] template_fields = ('bucket', 'prefix')
@apply_defaults
def __init__(self,
bucket,
prefix,
inactivity_period=60 * 60,
min_objects=1,
previous_num_objects=0,
allow_delete=True,
google_cloud_conn_id='google_cloud_default',
delegate_to=None,
*args, **kwargs):
super(GoogleCloudStorageUploadSessionCompleteSensor, self).__init__(*args, **kwargs)
self.bucket = bucket
self.prefix = prefix
self.inactivity_period = inactivity_period
self.min_objects = min_objects
self.previous_num_objects = previous_num_objects
self.inactivity_seconds = 0
self.allow_delete = allow_delete
self.google_cloud_conn_id = google_cloud_conn_id
self.delegate_to = delegate_to
self.last_activity_time = None
[docs] def is_bucket_updated(self, current_num_objects):
"""
Checks whether new objects have been uploaded and the inactivity_period
has passed and updates the state of the sensor accordingly.
:param current_num_objects: number of objects in bucket during last poke.
:type current_num_objects: int
"""
if current_num_objects > self.previous_num_objects:
# When new objects arrived, reset the inactivity_seconds
# previous_num_objects for the next poke.
self.log.info(
'''
New objects found at {} resetting last_activity_time.
'''.format(os.path.join(self.bucket, self.prefix)))
self.last_activity_time = get_time()
self.inactivity_seconds = 0
self.previous_num_objects = current_num_objects
elif current_num_objects < self.previous_num_objects:
# During the last poke interval objects were deleted.
if self.allow_delete:
self.previous_num_objects = current_num_objects
self.last_activity_time = get_time()
self.log.warning(
'''
Objects were deleted during the last
poke interval. Updating the file counter and
resetting last_activity_time.
'''
)
else:
raise RuntimeError(
'''
Illegal behavior: objects were deleted in {} between pokes.
'''.format(os.path.join(self.bucket, self.prefix))
)
else:
if self.last_activity_time:
self.inactivity_seconds = (
get_time() - self.last_activity_time).total_seconds()
else:
# Handles the first poke where last inactivity time is None.
self.last_activity_time = get_time()
self.inactivity_seconds = 0
if self.inactivity_seconds >= self.inactivity_period:
if current_num_objects >= self.min_objects:
self.log.info(
'''
SUCCESS:
Sensor found {} objects at {}.
Waited at least {} seconds, with no new objects dropped.
'''.format(
current_num_objects,
os.path.join(self.bucket, self.prefix),
self.inactivity_period))
return True
warn_msg = \
'''
FAILURE:
Inactivity Period passed,
not enough objects found in {}
'''.format(
os.path.join(self.bucket, self.prefix))
self.log.warning(warn_msg)
return False
return False
[docs] def poke(self, context):
hook = GoogleCloudStorageHook()
return self.is_bucket_updated(len(hook.list(self.bucket, prefix=self.prefix)))