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 – logging to the console


It's not always convenient to have to look at log files, particularly when we already have the agent screen open. Let's modify the agent to also log events to the screen.

  1. Restart the Flume agent with an additional argument:

    $ flume-ng agent --conf conf --conf-file 10a.conf --name agent1 -Dflume.root.logger=INFO,console
    

    You will receive the following response:

    Info: Sourcing environment configuration script /home/hadoop/flume/conf/flume-env.sh
    
    org.apache.flume.node.Application --conf-file 10a.conf --name agent1
    2012-08-19 00:41:45,462 (main) [INFO - org.apache.flume.lifecycle.LifecycleSupervisor.start(LifecycleSupervisor.java:67)] Starting lifec
    
  2. In another window, connect to the server via curl:

    $ curl telnet://localhost:3000
    
  3. Type in Hello and Flume on separate lines, hit Ctrl + C, and then check the agent window:

What just happened?

We added this example as it becomes very useful when debugging or creating new flows.

As seen in the previous example...