Toolkit com.ibm.streamsx.hdfs 4.4.1

General Information

The HDFS Toolkit provides operators that can read and write data from Hadoop Distributed File System (HDFS) version 2 or later.

HDFS2FileSource This operator opens a file on HDFS and sends out its contents in tuple format on its output port.

HDFS2FileSink This operator writes tuples that arrive on its input port to the output file that is named by the file parameter.

HDFS2DirectoryScan This operator repeatedly scans an HDFS directory and writes the names of new or modified files that are found in the directory to the output port. The operator sleeps between scans.

Note: The reference platforms that were used for testing are Hadoop 2.7.3, HDP .

You can access Hadoop remotely by specifying the webhdfs://hdfshost:webhdfsport schema in the URI that you use to connect to GPFS.

For example:

  () as lineSink1 = HDFS2FileSink(LineIn)
  {  
         param
              hdfsUri       : "clsadmin": 
              hdfsUser      : "webhdfs://your-hdfs-host-ip-address:8443";
              hdfsPassword  : "PASSWORD";
              file          : "LineInput.txt" ;
              
  }

Or "hdfs://your-hdfs-host-ip-address:8020" as hdfsUri

  () as lineSink1 = HDFS2FileSink(LineIn)
  {  
         param
              hdfsUri  : "hdfs": 
              hdfsUser : "hdfs://your-hdfs-host-ip-address:8020"
              file     : "LineInput.txt" ;                  
  }

Kerberos configuration

For Apache Hadoop 2.x, CDH, and HDP, you can optionally configure these operators to use the Kerberos protocol to authenticate users that read and write to HDFS.

Kerberos authentication provides a more secure way of accessing HDFS by providing user authentication.

To use Kerberos authentication, you must configure the authPrincipal and authKeytab operator parameters at compile time.

The authPrincipal parameter specifies the Kerberos principal, which is typically the principal that is created for the Streams instance owner.

The authKeytab parameter specifies the keytab file that is created for the principal.

For Kerberos authentication it is required to create a Principal and a Keytab for each user.

If you use ambari to configure your hadoop server, you can create principals and keytabs via ambari (Enable Kerberos).

More details about Kerberos configuration:

  https://developer.ibm.com/hadoop/2016/08/18/overview-of-kerberos-in-iop-4-2/

Copy the created keytab into local streams server for example in etc directory of your SPL application.

Before you start your SPL application, you can check the keytab with kinit tool

  kinit -k -t KeytabPath Principal

KeytabPath is the full path to the keytab file

For example:

  kinit -k -t /home/streamsadmin/workspace/myproject/etc/hdfs.headless.keytab hdfs-hdp2@HDP2.COM

In this case HDP2.com is the kerebors realm and the user is hdfs.

Here is an SPL example to write a file into hadoop server with kerberos configuration.

    () as lineSink1 = HDFS2FileSink(LineIn)
    {
        param
            authKeytab     : "etc/hdfs.headless.keytab" ;
            authPrincipal  : "hdfs-hdp2@HDP2.COM" ;
            configPath     : "etc" ;
            file           : "LineInput.txt" ;
    }

Developing and running applications that use the HDFS Toolkit

Version

4.4.1

Required Product Version

4.2.0.0

Indexes

Namespaces

Operators

Namespaces

com.ibm.streamsx.hdfs

Operators

• HDFS2DirectoryScan
• HDFS2FileSink
• HDFS2FileSource