pyarrow 实现hdfs和本地文件传输

pyarrow 实现hdfs和本地文件传输

python环境下支持好几种与hdfs文件同步接口，如：pyhdfs，hdfs，libhdfs，pyarrow，shell等。考虑到易用性以及本地环境（公司集群禁掉了http服务）,本文介绍使用pyarrow 以一种优雅的方式进行本地文件与hdfs同步。

1. 安装pyarrow

• 在线安装
  pip install pyarrow

• 离线安装
  pyarrow-官网下载

下载完.whl文件后，通过 pip instal pyarrow-9.0.0-cp37-cp37m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl

• 配置环境变量
  需要使用hadoop目录下的jar包。

# 这里根据实际情况配置，在linux环境下
export PATH=$JAVA_HOME/bin:$HBASE_HOME/bin:$HADOOP_HOME/bin:$HIVE_HOME/bin:$SPARK_HOME/bin:$SQOOP_HOME/bin:$PATH:${HOME}/.local/bin:$    {DISTCP_HOME}:$JAVA_HOME/jre/bin:$PATH
export CLASSPATH=`$HADOOP_HOME/bin/hadoop classpath --glob`
export HADOOP_LIBEXEC_DIR=${HADOOP_HOME}/libexec

参考官网：

export CLASSPATH=`$HADOOP_HOME/bin/hadoop classpath --glob`
# or on Windows
%HADOOP_HOME%/bin/hadoop classpath --glob > %CLASSPATH%

2. 相关代码

2.1. hdfs->本地

HdfsPath,LocalPath分别为自定义的类，主要是实现fs.HadoopFileSystem(host="***", port=, user="***", kerb_ticket=None),fs.LocalFileSystem对象，
下面2.1,2.3功能 示例较完整。简单的测试实例见2.3.

def hdfs_to_local(hdfs_path: HdfsPath, local_path: LocalPath):
    """
    同步文件，这里有两种情况：
    1）若是单个文件，可以直接打开用文件流的方式写进入；
    2）若是目录，首先创建文件选择器，进而获取文件目录下的所有文件依次按照 法1） 方式传输。
    :param hdfs_path:
    :param local_path:
    :return:
    """
    hdfs = hdfs_path.get_hdfs()
    local = local_path.get_local()
    _logger.info(f"复制hdfs文件 {hdfs_path.path} 到本地{local_path.path}.")
    # hdfs 本地文件做规则化处理
    if hdfs_path.path.endswith('/'):
        hdfs_path.path = hdfs_path.path[:-1]
    if local_path.path.endswith('/'):
        local_path.path = local_path.path[:-1]
    len_hdfs_path = len(str(Path(hdfs_path.path).absolute().parent))
    file_list = []
    # 如果是文件，按照父目录传递
    if hdfs_path.isFile():
        file_list.append(hdfs.get_file_info(hdfs_path.path))
    elif hdfs_path.isDir():
        file_select = fs.FileSelector(hdfs_path.path, allow_not_found=True, recursive=True)
        file_list = hdfs.get_file_info(file_select)

    _logger.info(f"共有{len(file_list)}个文件需要复制...")
    for file in file_list:
        local_filename = local_path.path + file.path[len_hdfs_path:]
        # 判断是否为文件、文件夹
        if file.type.value == 3:
            local.create_dir(local_filename)
        elif file.type.value == 2:
            with hdfs.open_input_stream(file.path) as read_file, local.open_append_stream(
                    local_filename) as write_file:
                write_file.write(read_file.readall())
        else:
            print("hdfs_file -> local_file 文件下载异常！")
            raise Exception(f"\n{file} 文件为空。\n")

2.2. 本地-> hdfs

def local_to_hdfs(local_path: LocalPath, hdfs_path: HdfsPath):
    """
    同上述方法类似
    :param local_path:
    :param hdfs_path:
    :return:
    """
    _logger.info(f"复制本地 文件 {local_path.path} 到hdfs {hdfs_path.path}.")
    local = local_path.get_local()
    hdfs = hdfs_path.get_hdfs()
    # hdfs 本地文件做规则化处理
    if hdfs_path.path.endswith('/'):
        hdfs_path.path = hdfs_path.path[:-1]
    if local_path.path.endswith('/'):
        local_path.path = local_path.path[:-1]

    len_local_path = len(str(Path(local_path.path).absolute().parent))
    file_list = []
    # 如果是文件，按照父目录传递
    if local_path.isFile():
        file_list.append(local.get_file_info(local_path.path))
    elif local_path.isDir():
        file_select = fs.FileSelector(local_path.path, allow_not_found=True, recursive=True)
        file_list = local.get_file_info(file_select)

    _logger.info(f"共有{len(file_list)}个文件需要复制...")
    for file in file_list:
        hdfs_filename = hdfs_path.path + file.path[len_local_path:]
        if file.type.value == 3:
            hdfs.create_dir(hdfs_filename)
        elif file.type.value == 2:
            with local.open_input_stream(file.path) as read_file, hdfs.open_output_stream(
                    hdfs_filename) as write_file:
                write_file.write(read_file.readall())
        else:
            print("local_file -> hdfs_file 文件下载异常！")
            raise Exception(f"\n{file} 文件为空。\n")

2.3. 一个简单的例子

可用于复制单个文件。

from abc import ABCMeta

from pyarrow import fs
from pyarrow.filesystem import FileSystem


class FileOperation(FileSystem, metaclass=ABCMeta):
    def __init__(self, host='localhost', port=9000, user='hdp-loan-dataai'):
        self.host = host
        self.port = port
        self.user = user
        self.hdfs = fs.HadoopFileSystem(host=host, port=port, user=user)
        self.local = fs.LocalFileSystem()

    def hdfs2local(self, src_path, des_path):
        """

        :param src_path: hdfs 文件路径
        :param des_path: 本地文件路径
        :return:
        """
        filename = src_path.split('/')[-1]
        try:
            with self.hdfs.open_input_stream(src_path) as read_file, self.local.open_append_stream(
                    des_path + '/' + filename) as write_file:
                write_file.write(read_file.readall())
        except Exception as e:
            print("hdfs_file -> local_file 文件下载异常！")

    
    def local2hdfs(self, src_path, des_path):
        """

        :param src_path:
        :param des_path:
        :return:
        """
        filename = src_path.split('/')[-1]
        # self.hdfs.create_dir(des_path + '/' + filename)
        with self.local.open_input_stream(src_path) as read_file, self.hdfs.open_output_stream(
                des_path + '/' + filename) as write_file:
            write_file.write(read_file.readall())

参考文章

pyarrow-官网下载
pyarrow API官网