def _get_fs_and_protocol(self):
storage_options = self.storage_options or {}
protocol, path = split_protocol(self.prefix_path)
cls = fsspec.get_filesystem_class(protocol)
options = cls._get_kwargs_from_urls(self.prefix_path)
update_storage_options(options, storage_options)
fs = cls(**options)
return fs, protocol
def _open_dataset(self):
import xarray as xr
import fsspec
assert fsspec.__version__ >= "0.3.6", "zarr plugin requires fsspec >= 0.3.6"
from fsspec import filesystem, get_mapper
from fsspec.utils import update_storage_options, infer_storage_options
storage_options = infer_storage_options(self.urlpath)
update_storage_options(storage_options, self.storage_options)
self._fs = filesystem(storage_options['protocol'])
if storage_options['protocol'] != 'file':
self._mapper = get_mapper(self.urlpath)
self._ds = xr.open_zarr(self._mapper, **self.kwargs)
else:
self._ds = xr.open_zarr(self.urlpath, **self.kwargs)
def __init__(self,
dataset_url,
hadoop_configuration=None,
connector=HdfsConnector,
hdfs_driver='libhdfs3',
user=None,
storage_options=None):
"""
Given a dataset URL and an optional hadoop configuration, parse and interpret the URL to
instantiate a pyarrow filesystem.
Interpretation of the URL ``scheme://hostname:port/path`` occurs in the following order:
1. If no ``scheme``, no longer supported, so raise an exception!
2. If ``scheme`` is ``file``, use local filesystem path.
3. If ``scheme`` is ``hdfs``:
a. Try the ``hostname`` as a namespace and attempt to connect to a name node.
1. If that doesn't work, try connecting directly to namenode ``hostname:port``.
b. If no host, connect to the default name node.
5. If ``scheme`` is ``s3``, use s3fs. The user must manually install s3fs before using s3
6. If ``scheme`` is ``gs``or ``gcs``, use gcsfs. The user must manually install gcsfs before using GCS
7. Fail otherwise.
:param dataset_url: The hdfs URL or absolute path to the dataset
:param hadoop_configuration: an optional hadoop configuration
:param connector: the HDFS connector object to use (ONLY override for testing purposes)
:param hdfs_driver: A string denoting the hdfs driver to use (if using a dataset on hdfs). Current choices are
libhdfs (java through JNI) or libhdfs3 (C++)
:param user: String denoting username when connecting to HDFS. None implies login user.
:param storage_options: Dict of kwargs forwarded to ``fsspec`` to initialize the filesystem.
"""
# Cache both the original URL and the resolved, urlparsed dataset_url
self._dataset_url = dataset_url
self._parsed_dataset_url = None
# Cache the instantiated filesystem object
self._filesystem = None
if isinstance(self._dataset_url, six.string_types):
self._parsed_dataset_url = urlparse(self._dataset_url)
else:
self._parsed_dataset_url = self._dataset_url
if not self._parsed_dataset_url.scheme:
# Case 1
raise ValueError(
'ERROR! A scheme-less dataset url ({}) is no longer supported. '
'Please prepend "file://" for local filesystem.'.format(
self._parsed_dataset_url.scheme))
elif self._parsed_dataset_url.scheme == 'file':
# Case 2: definitely local
self._filesystem = pyarrow.localfs
self._filesystem_factory = lambda: pyarrow.localfs
elif self._parsed_dataset_url.scheme == 'hdfs':
if hdfs_driver == 'libhdfs3':
# libhdfs3 does not do any namenode resolution itself so we do it manually. This is not necessary
# if using libhdfs
# Obtain singleton and force hadoop config evaluation
namenode_resolver = HdfsNamenodeResolver(hadoop_configuration)
# Since we can't tell for sure, first treat the URL as though it references a name service
if self._parsed_dataset_url.netloc:
# Case 3a: Use the portion of netloc before any port, which doesn't get lowercased
nameservice = self._parsed_dataset_url.netloc.split(':')[0]
namenodes = namenode_resolver.resolve_hdfs_name_service(
nameservice)
if namenodes:
self._filesystem = connector.connect_to_either_namenode(
namenodes, user=user)
self._filesystem_factory = lambda: connector.connect_to_either_namenode(
namenodes, user=user)
if self._filesystem is None:
# Case 3a1: That didn't work; try the URL as a namenode host
self._filesystem = connector.hdfs_connect_namenode(
self._parsed_dataset_url, user=user)
self._filesystem_factory = \
lambda url=self._dataset_url, user=user: \
connector.hdfs_connect_namenode(urlparse(url), user=user)
else:
# Case 3b: No netloc, so let's try to connect to default namenode
# HdfsNamenodeResolver will raise exception if it fails to connect.
nameservice, namenodes = namenode_resolver.resolve_default_hdfs_service(
)
filesystem = connector.connect_to_either_namenode(
namenodes, user=user)
self._filesystem_factory = lambda: connector.connect_to_either_namenode(
namenodes, user=user)
if filesystem is not None:
# Properly replace the parsed dataset URL once default namenode is confirmed
self._parsed_dataset_url = urlparse(
'hdfs://{}{}'.format(
nameservice, self._parsed_dataset_url.path))
self._filesystem = filesystem
else:
self._filesystem = connector.hdfs_connect_namenode(
self._parsed_dataset_url, hdfs_driver, user=user)
self._filesystem_factory = \
lambda url=self._dataset_url, user=user: \
connector.hdfs_connect_namenode(urlparse(url), hdfs_driver, user=user)
else:
# Fallback to fsspec to handle any other schemes
if not self._parsed_dataset_url.netloc:
raise ValueError(
'URLs must be of the form {}://bucket/path'.format(
self._parsed_dataset_url.scheme))
storage_options = storage_options or {}
protocol = self._parsed_dataset_url.scheme
cls = fsspec.get_filesystem_class(protocol)
options = cls._get_kwargs_from_urls(self._dataset_url)
update_storage_options(options, storage_options)
self._filesystem = cls(**options)
self._filesystem_factory = lambda: cls(**options) # pylint: disable=unnecessary-lambda