Source code for airflow.contrib.operators.gcs_download_operator

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import sys

from airflow.contrib.hooks.gcs_hook import GoogleCloudStorageHook
from airflow.models import BaseOperator
from airflow.models.xcom import MAX_XCOM_SIZE
from airflow.utils.decorators import apply_defaults


[docs]class GoogleCloudStorageDownloadOperator(BaseOperator): """ Downloads a file from Google Cloud Storage. If a filename is supplied, it writes the file to the specified location, alternatively one can set the ``store_to_xcom_key`` parameter to True push the file content into xcom. When the file size exceeds the maximum size for xcom it is recommended to write to a file. :param bucket: The Google cloud storage bucket where the object is. Must not contain 'gs://' prefix. (templated) :type bucket: str :param object: The name of the object to download in the Google cloud storage bucket. (templated) :type object: str :param filename: The file path, including filename, on the local file system (where the operator is being executed) that the file should be downloaded to. (templated) If no filename passed, the downloaded data will not be stored on the local file system. :type filename: str :param store_to_xcom_key: If this param is set, the operator will push the contents of the downloaded file to XCom with the key set in this parameter. If not set, the downloaded data will not be pushed to XCom. (templated) :type store_to_xcom_key: str :param google_cloud_storage_conn_id: The connection ID to use when connecting to Google cloud storage. :type google_cloud_storage_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', 'filename', 'store_to_xcom_key',)
[docs] ui_color = '#f0eee4'
@apply_defaults def __init__(self, bucket, object, filename=None, store_to_xcom_key=None, google_cloud_storage_conn_id='google_cloud_default', delegate_to=None, *args, **kwargs): super(GoogleCloudStorageDownloadOperator, self).__init__(*args, **kwargs) if filename is not None and store_to_xcom_key is not None: raise ValueError("Either filename or store_to_xcom_key can be set") self.bucket = bucket self.object = object self.filename = filename self.store_to_xcom_key = store_to_xcom_key self.google_cloud_storage_conn_id = google_cloud_storage_conn_id self.delegate_to = delegate_to
[docs] def execute(self, context): self.log.info('Executing download: %s, %s, %s', self.bucket, self.object, self.filename) hook = GoogleCloudStorageHook( google_cloud_storage_conn_id=self.google_cloud_storage_conn_id, delegate_to=self.delegate_to ) if self.store_to_xcom_key: file_bytes = hook.download(bucket=self.bucket, object=self.object) if sys.getsizeof(file_bytes) < MAX_XCOM_SIZE: context['ti'].xcom_push(key=self.store_to_xcom_key, value=file_bytes) else: raise RuntimeError( 'The size of the downloaded file is too large to push to XCom!' ) else: hook.download(bucket=self.bucket, object=self.object, filename=self.filename)

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