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from airflow.exceptions import AirflowException
from airflow.hooks.base_hook import BaseHook
from azure.storage.blob import BlockBlobService
[docs]class WasbHook(BaseHook):
"""
Interacts with Azure Blob Storage through the wasb:// protocol.
Additional options passed in the 'extra' field of the connection will be
passed to the `BlockBlockService()` constructor. For example, authenticate
using a SAS token by adding {"sas_token": "YOUR_TOKEN"}.
:param wasb_conn_id: Reference to the wasb connection.
:type wasb_conn_id: str
"""
def __init__(self, wasb_conn_id='wasb_default'):
self.conn_id = wasb_conn_id
self.connection = self.get_conn()
[docs] def get_conn(self):
"""Return the BlockBlobService object."""
conn = self.get_connection(self.conn_id)
service_options = conn.extra_dejson
return BlockBlobService(account_name=conn.login,
account_key=conn.password, **service_options)
[docs] def check_for_blob(self, container_name, blob_name, **kwargs):
"""
Check if a blob exists on Azure Blob Storage.
:param container_name: Name of the container.
:type container_name: str
:param blob_name: Name of the blob.
:type blob_name: str
:param kwargs: Optional keyword arguments that
`BlockBlobService.exists()` takes.
:type kwargs: object
:return: True if the blob exists, False otherwise.
:rtype: bool
"""
return self.connection.exists(container_name, blob_name, **kwargs)
[docs] def check_for_prefix(self, container_name, prefix, **kwargs):
"""
Check if a prefix exists on Azure Blob storage.
:param container_name: Name of the container.
:type container_name: str
:param prefix: Prefix of the blob.
:type prefix: str
:param kwargs: Optional keyword arguments that
`BlockBlobService.list_blobs()` takes.
:type kwargs: object
:return: True if blobs matching the prefix exist, False otherwise.
:rtype: bool
"""
matches = self.connection.list_blobs(container_name, prefix,
num_results=1, **kwargs)
return len(list(matches)) > 0
[docs] def load_file(self, file_path, container_name, blob_name, **kwargs):
"""
Upload a file to Azure Blob Storage.
:param file_path: Path to the file to load.
:type file_path: str
:param container_name: Name of the container.
:type container_name: str
:param blob_name: Name of the blob.
:type blob_name: str
:param kwargs: Optional keyword arguments that
`BlockBlobService.create_blob_from_path()` takes.
:type kwargs: object
"""
# Reorder the argument order from airflow.hooks.S3_hook.load_file.
self.connection.create_blob_from_path(container_name, blob_name,
file_path, **kwargs)
[docs] def load_string(self, string_data, container_name, blob_name, **kwargs):
"""
Upload a string to Azure Blob Storage.
:param string_data: String to load.
:type string_data: str
:param container_name: Name of the container.
:type container_name: str
:param blob_name: Name of the blob.
:type blob_name: str
:param kwargs: Optional keyword arguments that
`BlockBlobService.create_blob_from_text()` takes.
:type kwargs: object
"""
# Reorder the argument order from airflow.hooks.S3_hook.load_string.
self.connection.create_blob_from_text(container_name, blob_name,
string_data, **kwargs)
[docs] def get_file(self, file_path, container_name, blob_name, **kwargs):
"""
Download a file from Azure Blob Storage.
:param file_path: Path to the file to download.
:type file_path: str
:param container_name: Name of the container.
:type container_name: str
:param blob_name: Name of the blob.
:type blob_name: str
:param kwargs: Optional keyword arguments that
`BlockBlobService.create_blob_from_path()` takes.
:type kwargs: object
"""
return self.connection.get_blob_to_path(container_name, blob_name,
file_path, **kwargs)
[docs] def read_file(self, container_name, blob_name, **kwargs):
"""
Read a file from Azure Blob Storage and return as a string.
:param container_name: Name of the container.
:type container_name: str
:param blob_name: Name of the blob.
:type blob_name: str
:param kwargs: Optional keyword arguments that
`BlockBlobService.create_blob_from_path()` takes.
:type kwargs: object
"""
return self.connection.get_blob_to_text(container_name,
blob_name,
**kwargs).content
[docs] def delete_file(self, container_name, blob_name, is_prefix=False,
ignore_if_missing=False, **kwargs):
"""
Delete a file from Azure Blob Storage.
:param container_name: Name of the container.
:type container_name: str
:param blob_name: Name of the blob.
:type blob_name: str
:param is_prefix: If blob_name is a prefix, delete all matching files
:type is_prefix: bool
:param ignore_if_missing: if True, then return success even if the
blob does not exist.
:type ignore_if_missing: bool
:param kwargs: Optional keyword arguments that
`BlockBlobService.create_blob_from_path()` takes.
:type kwargs: object
"""
if is_prefix:
blobs_to_delete = [
blob.name for blob in self.connection.list_blobs(
container_name, prefix=blob_name, **kwargs
)
]
elif self.check_for_blob(container_name, blob_name):
blobs_to_delete = [blob_name]
else:
blobs_to_delete = []
if not ignore_if_missing and len(blobs_to_delete) == 0:
raise AirflowException('Blob(s) not found: {}'.format(blob_name))
for blob_uri in blobs_to_delete:
self.log.info("Deleting blob: " + blob_uri)
self.connection.delete_blob(container_name,
blob_uri,
delete_snapshots='include',
**kwargs)