Source code for airflow.providers.apache.hdfs.hooks.hdfs

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"""Hook for HDFS operations"""
from typing import Any, Optional

from airflow.configuration import conf
from airflow.exceptions import AirflowException
from airflow.hooks.base import BaseHook

try:
    from snakebite.client import AutoConfigClient, Client, HAClient, Namenode

[docs]    snakebite_loaded = True
except ImportError:
    snakebite_loaded = False


[docs]class HDFSHookException(AirflowException):
    """Exception specific for HDFS"""


[docs]class HDFSHook(BaseHook):
    """
    Interact with HDFS. This class is a wrapper around the snakebite library.

    :param hdfs_conn_id: Connection id to fetch connection info
    :param proxy_user: effective user for HDFS operations
    :param autoconfig: use snakebite's automatically configured client
    """

[docs]    conn_name_attr = 'hdfs_conn_id'
[docs]    default_conn_name = 'hdfs_default'
[docs]    conn_type = 'hdfs'
[docs]    hook_name = 'HDFS'

    def __init__(
        self, hdfs_conn_id: str = 'hdfs_default', proxy_user: Optional[str] = None, autoconfig: bool = False
    ):
        super().__init__()
        if not snakebite_loaded:
            raise ImportError(
                'This HDFSHook implementation requires snakebite, but '
                'snakebite is not compatible with Python 3 '
                '(as of August 2015). Please help by submitting a PR!'
            )
        self.hdfs_conn_id = hdfs_conn_id
        self.proxy_user = proxy_user
        self.autoconfig = autoconfig

[docs]    def get_conn(self) -> Any:
        """Returns a snakebite HDFSClient object."""
        # When using HAClient, proxy_user must be the same, so is ok to always
        # take the first.
        effective_user = self.proxy_user
        autoconfig = self.autoconfig
        use_sasl = conf.get('core', 'security') == 'kerberos'

        try:
            connections = self.get_connections(self.hdfs_conn_id)

            if not effective_user:
                effective_user = connections[0].login
            if not autoconfig:
                autoconfig = connections[0].extra_dejson.get('autoconfig', False)
            hdfs_namenode_principal = connections[0].extra_dejson.get('hdfs_namenode_principal')
        except AirflowException:
            if not autoconfig:
                raise

        if autoconfig:
            # will read config info from $HADOOP_HOME conf files
            client = AutoConfigClient(effective_user=effective_user, use_sasl=use_sasl)
        elif len(connections) == 1:
            client = Client(
                connections[0].host,
                connections[0].port,
                effective_user=effective_user,
                use_sasl=use_sasl,
                hdfs_namenode_principal=hdfs_namenode_principal,
            )
        elif len(connections) > 1:
            name_node = [Namenode(conn.host, conn.port) for conn in connections]
            client = HAClient(
                name_node,
                effective_user=effective_user,
                use_sasl=use_sasl,
                hdfs_namenode_principal=hdfs_namenode_principal,
            )
        else:
            raise HDFSHookException("conn_id doesn't exist in the repository and autoconfig is not specified")

        return client