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"""This module contains Google Cloud Storage sensors."""
import os
from datetime import datetime
from typing import Callable, List, Optional, Sequence, Set, Union
from airflow.exceptions import AirflowException
from airflow.providers.google.cloud.hooks.gcs import GCSHook
from airflow.sensors.base import BaseSensorOperator, poke_mode_only
from airflow.utils.decorators import apply_defaults
[docs]class GCSObjectExistenceSensor(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 using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:type delegate_to: str
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
:type impersonation_chain: Union[str, Sequence[str]]
"""
[docs] template_fields = (
'bucket',
'object',
'impersonation_chain',
)
@apply_defaults
def __init__(
self,
*,
bucket: str,
object: str, # pylint: disable=redefined-builtin
google_cloud_conn_id: str = 'google_cloud_default',
delegate_to: Optional[str] = None,
impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.bucket = bucket
self.object = object
self.google_cloud_conn_id = google_cloud_conn_id
self.delegate_to = delegate_to
self.impersonation_chain = impersonation_chain
[docs] def poke(self, context: dict) -> bool:
self.log.info('Sensor checks existence of : %s, %s', self.bucket, self.object)
hook = GCSHook(
google_cloud_storage_conn_id=self.google_cloud_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
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 GCSObjectUpdateSensor(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 using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:type delegate_to: str
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
:type impersonation_chain: Union[str, Sequence[str]]
"""
[docs] template_fields = (
'bucket',
'object',
'impersonation_chain',
)
@apply_defaults
def __init__(
self,
bucket: str,
object: str, # pylint: disable=redefined-builtin
ts_func: Callable = ts_function,
google_cloud_conn_id: str = 'google_cloud_default',
delegate_to: Optional[str] = None,
impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
**kwargs,
) -> None:
super().__init__(**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
self.impersonation_chain = impersonation_chain
[docs] def poke(self, context: dict) -> bool:
self.log.info('Sensor checks existence of : %s, %s', self.bucket, self.object)
hook = GCSHook(
google_cloud_storage_conn_id=self.google_cloud_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
return hook.is_updated_after(self.bucket, self.object, self.ts_func(context))
[docs]class GCSObjectsWtihPrefixExistenceSensor(BaseSensorOperator):
"""
Checks for the existence of GCS objects at a given prefix, passing matches via XCom.
When files matching the given prefix are found, the poke method's criteria will be
fulfilled and the matching objects will be returned from the operator and passed
through XCom for downstream tasks.
: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 using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:type delegate_to: str
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
:type impersonation_chain: Union[str, Sequence[str]]
"""
[docs] template_fields = (
'bucket',
'prefix',
'impersonation_chain',
)
@apply_defaults
def __init__(
self,
bucket: str,
prefix: str,
google_cloud_conn_id: str = 'google_cloud_default',
delegate_to: Optional[str] = None,
impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.bucket = bucket
self.prefix = prefix
self.google_cloud_conn_id = google_cloud_conn_id
self.delegate_to = delegate_to
self._matches: List[str] = []
self.impersonation_chain = impersonation_chain
[docs] def poke(self, context: dict) -> bool:
self.log.info('Sensor checks existence of objects: %s, %s', self.bucket, self.prefix)
hook = GCSHook(
google_cloud_storage_conn_id=self.google_cloud_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
self._matches = hook.list(self.bucket, prefix=self.prefix)
return bool(self._matches)
[docs] def execute(self, context: dict) -> List[str]:
"""Overridden to allow matches to be passed"""
super().execute(context)
return self._matches
[docs]def get_time():
"""
This is just a wrapper of datetime.datetime.now to simplify mocking in the
unittests.
"""
return datetime.now()
[docs]@poke_mode_only
class GCSUploadSessionCompleteSensor(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, this sensor will no behave correctly
in reschedule mode, as the state of the listed objects in the GCS bucket will
be lost between rescheduled invocations.
: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: float
:param min_objects: The minimum number of objects needed for upload session
to be considered valid.
:type min_objects: int
:param previous_objects: The set of object ids found during the last poke.
:type previous_objects: set[str]
: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 using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:type delegate_to: str
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
:type impersonation_chain: Union[str, Sequence[str]]
"""
[docs] template_fields = (
'bucket',
'prefix',
'impersonation_chain',
)
@apply_defaults
def __init__(
self,
bucket: str,
prefix: str,
inactivity_period: float = 60 * 60,
min_objects: int = 1,
previous_objects: Optional[Set[str]] = None,
allow_delete: bool = True,
google_cloud_conn_id: str = 'google_cloud_default',
delegate_to: Optional[str] = None,
impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.bucket = bucket
self.prefix = prefix
if inactivity_period < 0:
raise ValueError("inactivity_period must be non-negative")
self.inactivity_period = inactivity_period
self.min_objects = min_objects
self.previous_objects = previous_objects if previous_objects else set()
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
self.impersonation_chain = impersonation_chain
self.hook: Optional[GCSHook] = None
[docs] def _get_gcs_hook(self) -> Optional[GCSHook]:
if not self.hook:
self.hook = GCSHook(
gcp_conn_id=self.google_cloud_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
return self.hook
[docs] def is_bucket_updated(self, current_objects: Set[str]) -> bool:
"""
Checks whether new objects have been uploaded and the inactivity_period
has passed and updates the state of the sensor accordingly.
:param current_objects: set of object ids in bucket during last poke.
:type current_objects: set[str]
"""
current_num_objects = len(current_objects)
if current_objects > self.previous_objects:
# When new objects arrived, reset the inactivity_seconds
# and update previous_objects for the next poke.
self.log.info(
"New objects found at %s resetting last_activity_time.",
os.path.join(self.bucket, self.prefix),
)
self.log.debug("New objects: %s", "\n".join(current_objects - self.previous_objects))
self.last_activity_time = get_time()
self.inactivity_seconds = 0
self.previous_objects = current_objects
return False
if self.previous_objects - current_objects:
# During the last poke interval objects were deleted.
if self.allow_delete:
self.previous_objects = current_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.
%s
""",
self.previous_objects - current_objects,
)
return False
raise AirflowException(
"""
Illegal behavior: objects were deleted in {} between pokes.
""".format(
os.path.join(self.bucket, self.prefix)
)
)
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:
path = os.path.join(self.bucket, self.prefix)
if current_num_objects >= self.min_objects:
self.log.info(
"""SUCCESS:
Sensor found %s objects at %s.
Waited at least %s seconds, with no new objects dropped.
""",
current_num_objects,
path,
self.inactivity_period,
)
return True
self.log.error("FAILURE: Inactivity Period passed, not enough objects found in %s", path)
return False
return False
[docs] def poke(self, context: dict) -> bool:
return self.is_bucket_updated(
set(self._get_gcs_hook().list(self.bucket, prefix=self.prefix)) # type: ignore[union-attr]
)