hdfs 1.4.3

HdfsCLI: a command line interface for WebHDFS.

HdfsCLI

API and command line interface for HDFS.

Features

• Python bindings for the WebHDFS API, supporting both secure and insecure clusters.

• Lightweight CLI with aliases for convenient namenode URL caching.

• Additional functionality through optional extensions:

  • avro, allowing reading/writing Avro files directly from JSON.

  • dataframe, enabling fast loading/saving of pandas dataframes from/to HDFS.

  • kerberos, adding support for Kerberos authenticated clusters.

Installation

Using pip:

$ pip install hdfs

By default none of the package requirements for extensions are installed. To do so simply suffix the package name with the desired extensions:

$ pip install hdfs[avro,dataframe,kerberos]

By default the command line entry point will be named hdfs. If this conflicts with another utility, you can choose another name by specifying the HDFSCLI_ENTRY_POINT environment variable:

$ HDFSCLI_ENTRY_POINT=hdfscli pip install hdfs

Quickstart

API

Sample snippet using a python client to create a file on HDFS, rename it, download it locally, and finally delete the remote copy.

from hdfs import TokenClient

client = TokenClient('http://namenode:port', 'foo', root='/user/alice')
client.write('hello.md', 'Hello, world!')
client.rename('hello.md', 'hello.rst')
client.download('hello.rst', 'hello.rst')
client.delete('hello.rst')

Refer to the documentation for the full API and extensions.

CLI

Sample commands (see below for how to configure cluster aliases):

$ # Write a single file to HDFS.
$ hdfs static/weights.json --write <weights.json

$ # Read a file from HDFS and storing locally.
$ hdfs export/results --read >"results-$(date +%F)"

$ # Read a file from HDFS and append it to a local log file.
$ hdfs --read logs/1987-03-23 >>logs

Cf. hdfs --help for the full list of commands and options.

Configuration

You can configure which clusters to connect to by writing your own configuration at ~/.hdfsrc (or elsewhere by setting the HDFSCLI_RCPATH environment variable correspondingly). This will also enable the Client.from_alias method.

Sample configuration defining two aliases, foo and bar:

[hdfs]
default.alias = foo # Used when no alias is specified at the command line.

[foo_alias]
client = KerberosClient
root = /some/directory
url = https://url.to.namenode:port
verify = false

[bar_alias]
url = http://url.to.another.namenode:port

All options other than url can be omitted. client determines which class to use (defaulting to the generic Client), and the remaining options are passed as named arguments to the appropriate constructor.

Testing

HdfsCLI is tested against both WebHDFS and HttpFS. There are two ways of running tests:

$ HDFSCLI_TEST_ALIAS=foo nosetests # Using an alias.
$ HDFSCLI_TEST_URL=http://localhost:50070 nosetests # Using the URL.

See scripts/ for helpers to set up a suitable HDFS cluster.