Book Image

Hadoop Beginner's Guide

Book Image

Hadoop Beginner's Guide

Overview of this book

Data is arriving faster than you can process it and the overall volumes keep growing at a rate that keeps you awake at night. Hadoop can help you tame the data beast. Effective use of Hadoop however requires a mixture of programming, design, and system administration skills."Hadoop Beginner's Guide" removes the mystery from Hadoop, presenting Hadoop and related technologies with a focus on building working systems and getting the job done, using cloud services to do so when it makes sense. From basic concepts and initial setup through developing applications and keeping the system running as the data grows, the book gives the understanding needed to effectively use Hadoop to solve real world problems.Starting with the basics of installing and configuring Hadoop, the book explains how to develop applications, maintain the system, and how to use additional products to integrate with other systems.While learning different ways to develop applications to run on Hadoop the book also covers tools such as Hive, Sqoop, and Flume that show how Hadoop can be integrated with relational databases and log collection.In addition to examples on Hadoop clusters on Ubuntu uses of cloud services such as Amazon, EC2 and Elastic MapReduce are covered.
Table of Contents (19 chapters)
Hadoop Beginner's Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Time for action – capturing the output of a command to a flat file


Let's show this in action, along the way demonstrating a new kind of source as well.

  1. Create the following file as agent2.conf within the Flume working directory:

    agent2.sources = execsource
    agent2.sinks = filesink
    agent2.channels = filechannel
    
    agent2.sources.execsource.type = exec
    agent2.sources.execsource.command = cat /home/hadoop/message
    
    agent2.sinks.filesink.type = FILE_ROLL
    agent2.sinks.filesink.sink.directory = /home/hadoop/flume/files
    agent2.sinks.filesink.sink.rollInterval = 0
    
    agent2.channels.filechannel.type = file
    agent2.channels.filechannel.checkpointDir = /home/hadoop/flume/fc/checkpoint
    agent2.channels.filechannel.dataDirs = /home/hadoop/flume/fc/data
    
    agent2.sources.execsource.channels = filechannel
    agent2.sinks.filesink.channel = filechannel
  2. Create a simple test file in the home directory:

    $ echo "Hello again Flume!" > /home/hadoop/message
    
  3. Start the agent:

    $ flume-ng agent --conf conf --conf-file agent2...