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from hdfs import InsecureClient, HdfsError
from airflow import configuration
from airflow.exceptions import AirflowException
from airflow.hooks.base_hook import BaseHook
from airflow.utils.log.logging_mixin import LoggingMixin
[docs]_kerberos_security_mode = configuration.conf.get("core", "security") == "kerberos"
if _kerberos_security_mode:
try:
from hdfs.ext.kerberos import KerberosClient
except ImportError:
[docs] log = LoggingMixin().log
log.error("Could not load the Kerberos extension for the WebHDFSHook.")
raise
[docs]class AirflowWebHDFSHookException(AirflowException):
pass
[docs]class WebHDFSHook(BaseHook):
"""
Interact with HDFS. This class is a wrapper around the hdfscli library.
:param webhdfs_conn_id: The connection id for the webhdfs client to connect to.
:type webhdfs_conn_id: str
:param proxy_user: The user used to authenticate.
:type proxy_user: str
"""
def __init__(self, webhdfs_conn_id='webhdfs_default', proxy_user=None):
super(WebHDFSHook, self).__init__(webhdfs_conn_id)
self.webhdfs_conn_id = webhdfs_conn_id
self.proxy_user = proxy_user
[docs] def get_conn(self):
"""
Establishes a connection depending on the security mode set via config or environment variable.
:return: a hdfscli InsecureClient or KerberosClient object.
:rtype: hdfs.InsecureClient or hdfs.ext.kerberos.KerberosClient
"""
connections = self.get_connections(self.webhdfs_conn_id)
for connection in connections:
try:
self.log.debug('Trying namenode %s', connection.host)
client = self._get_client(connection)
client.status('/')
self.log.debug('Using namenode %s for hook', connection.host)
return client
except HdfsError as hdfs_error:
self.log.debug('Read operation on namenode %s failed with error: %s',
connection.host, hdfs_error)
hosts = [connection.host for connection in connections]
error_message = 'Read operations failed on the namenodes below:\n{hosts}'.format(
hosts='\n'.join(hosts))
raise AirflowWebHDFSHookException(error_message)
[docs] def _get_client(self, connection):
connection_str = 'http://{host}:{port}'.format(host=connection.host, port=connection.port)
if _kerberos_security_mode:
client = KerberosClient(connection_str)
else:
proxy_user = self.proxy_user or connection.login
client = InsecureClient(connection_str, user=proxy_user)
return client
[docs] def check_for_path(self, hdfs_path):
"""
Check for the existence of a path in HDFS by querying FileStatus.
:param hdfs_path: The path to check.
:type hdfs_path: str
:return: True if the path exists and False if not.
:rtype: bool
"""
conn = self.get_conn()
status = conn.status(hdfs_path, strict=False)
return bool(status)
[docs] def load_file(self, source, destination, overwrite=True, parallelism=1, **kwargs):
r"""
Uploads a file to HDFS.
:param source: Local path to file or folder.
If it's a folder, all the files inside of it will be uploaded.
.. note:: This implies that folders empty of files will not be created remotely.
:type source: str
:param destination: PTarget HDFS path.
If it already exists and is a directory, files will be uploaded inside.
:type destination: str
:param overwrite: Overwrite any existing file or directory.
:type overwrite: bool
:param parallelism: Number of threads to use for parallelization.
A value of `0` (or negative) uses as many threads as there are files.
:type parallelism: int
:param \**kwargs: Keyword arguments forwarded to :meth:`hdfs.client.Client.upload`.
"""
conn = self.get_conn()
conn.upload(hdfs_path=destination,
local_path=source,
overwrite=overwrite,
n_threads=parallelism,
**kwargs)
self.log.debug("Uploaded file %s to %s", source, destination)