2. WebHDFS User Guide

The following examples use the curl command tool to access HDFS via WebHDFS REST API.

  • To read a file (for example: /foo/bar):

    curl -i -L "http://$<Host_Name>:$<Port>/webhdfs/v1/foo/bar?op=OPEN"
  • To list a directory (for example: /foo):

    curl -i "http://$<Host_Name>:$<Port>/webhdfs/v1/foo/?op=LISTSTATUS"
  • To list the status of a file (for example: /foo/bar) or a directory:

    curl -i "http://$<Host_Name>:$<Port>/webhdfs/v1/foo/bar?op=GETFILESTATUS"
  • To write a file into a /foo/new file:

    curl -i -X PUT -L "http://$<Host_Name>:$<Port>/webhdfs/v1/foo/newFile?op=CREATE" -T newFile
  • To rename the /foo/bar file to /foo/bar3:

    curl -i -X PUT "http://$<Host_Name>:$<Port>/webhdfs/v1/foo/bar?op=RENAME&destination=/foo/bar2"
  • Make new directory /foo2:

    curl -i -X PUT "http://$<Host_Name>:$<Port>/webhdfs/v1/foo2?op=MKDIRS&permission=711"

 2.1. Authentication

When security is enabled, authentication is performed by either Hadoop delegation token or Kerberos SPNEGO. If a token is set in the delegation query parameter, the authenticated user is the user encoded in the token. If the delegation parameter is not set, the user is authenticated by Kerberos SPNEGO.

Below are examples using the curl command tool.

  • Login to the Key Distribution Center (KDC).

  • Provide any arbitrary user name and a null password.

  • Execute the following commands:

    curl --negotiate -u:anyUser "http://$<Host_Name>:$<Port>/webhdfs/v1/foo/bar?op=OPEN
    curl --negotiate -u:anyUser -b ~/cookies.txt -c ~/cookies.txt http://$<Host_Name>:$<Port>/webhdfs/v1/foo/bar?op=OPEN


    • --negotiate option enables SPNEGO in curl.

    • -u:anyUser option is mandatory when the user name is not specified instead, a Kerberos established user (via kinit) is used. (Ensure that you provide any user name and enter a null password when prompted.)

    • -b and -c options are used for storing and sending HTTP cookies.