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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.
"""
def __init__(self, webhdfs_conn_id='webhdfs_default', proxy_user=None):
self.webhdfs_conn_id = webhdfs_conn_id
self.proxy_user = proxy_user
[docs] def get_conn(self):
"""
Returns a hdfscli InsecureClient object.
"""
nn_connections = self.get_connections(self.webhdfs_conn_id)
for nn in nn_connections:
try:
self.log.debug('Trying namenode %s', nn.host)
connection_str = 'http://{nn.host}:{nn.port}'.format(nn=nn)
if _kerberos_security_mode:
client = KerberosClient(connection_str)
else:
proxy_user = self.proxy_user or nn.login
client = InsecureClient(connection_str, user=proxy_user)
client.status('/')
self.log.debug('Using namenode %s for hook', nn.host)
return client
except HdfsError as e:
self.log.debug(
"Read operation on namenode %s "
"failed with error: %s", nn.host, e
)
nn_hosts = [c.host for c in nn_connections]
no_nn_error = "Read operations failed " \
"on the namenodes below:\n{}".format("\n".join(nn_hosts))
raise AirflowWebHDFSHookException(no_nn_error)
[docs] def check_for_path(self, hdfs_path):
"""
Check for the existence of a path in HDFS by querying FileStatus.
"""
c = self.get_conn()
return bool(c.status(hdfs_path, strict=False))
[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 a folder, all the files
inside of it will be uploaded (note that 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:`upload`.
"""
c = self.get_conn()
c.upload(hdfs_path=destination,
local_path=source,
overwrite=overwrite,
n_threads=parallelism,
**kwargs)
self.log.debug("Uploaded file %s to %s", source, destination)