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=====Linux Hadoop Minimal VM Notes=====
**Version:** .42\\
**Date:** June 3, 2019\\
**Author:** Douglas Eadline\\
**Email:** deadline(you know what goes here)basement-supercomputing.com

**Unless otherwise noted, all course content, notes, and examples are
(c) Copyright Basement Supercomputing 2019, All rights reserved.**

====What Is This?====

The Linux Hadoop Minimal is a virtual machine (VM) that can be used to
try the examples presented in the following on-line courses entitled:

  * [[https://www.oreilly.com/search/?query=Practical%20Linux%20Command%20Line%20for%20Data%20Engineers%20and%20Analysts%20Eadline| Practical Linux Command Line for Data Engineers and Analysts]] 
  * [[https://www.safaribooksonline.com/search/?query=Hands-on%20Introduction%20to%20Apache%20Hadoop%20and%20Spark%20Programming&field=title|Hands-on Introduction to Apache Hadoop and Spark Programming]]

It can also be used for the [[https://www.clustermonkey.net/download/LiveLessons/Hadoop_Fundamentals/|examples]] provided in the companion on-line
video tutorial (14+ hours):

  * [[https://www.safaribooksonline.com/library/view/hadoop-and-spark/9780134770871|Hadoop® and Spark Fundamentals: LiveLessons]]

The machine has many important Hadoop and Spark packages installed and at the same time tries to keep the resource usage as low as possible so the VM can used on most laptops. (See below for resource recommendations)

To learn more about the course and my other analytics books and videos, go to:

  * [[https://www.safaribooksonline.com/search/?query=eadline|Safari Books Online]]

PLEASE NOTE: This version of Linux Hadoop Minimal (LHM) is still considered
"beta."  If you use it and find problems, please send any issues to
deadline(you know what goes here)basement-supercomputing.com with "LHM" in the subject line.

====Student Usage====
If you have taken the "Hands-on" course mentioned above, you can download the ''NOTES.txt'' files, examples, and data archive directly to the VM using ''wget'' The archive is in both compressed tar (tgz) and Zip (zip) format. It is recommended that you either make a new user account or use the "hands-on" account for the archive (and run most of the examples from this account).

For instance, to download and extract the archive for the "Hands-on" course from //within the VM//:

  wget https://www.clustermonkey.net/download/Hands-on_Hadoop_Spark/Hands_On_Hadoop_Spark-V1.5.tgz
  tar xvzf Hands_On_Hadoop_Spark-V1.5.1.tgz

Similarly, for the "Linux Command Line" course (do this within the VM)

  wget https://www.clustermonkey.net/download/Hands-on_Hadoop_Spark/Linux-Command-Line-V1.0.tgz
  tar xvzf Linux-Command-Line-V1.0.tgz

If you want to move files from your local machine to the VM, then you can use ''scp''
on your host. (''scp'' natively available on Linux and Macintosh systems, it is part of the
MobaXterm package on Windows)

  scp -P2222  SOURCE-FILE USERNAME@127.0.0.1:PATH

''USERNAME'' is a valid account on the VM. There is a user account called ''hands-on'' that can
be used for most of the examples. Therefore, the command to copy file (''SOURCE-FILE'') from your
host system to the VM is (it places the file in ''/home/hands-on'' in the VM):

   scp -P2222  SOURCE-FILE hands-on@127.0.0.1:/home/hands-on

See the [[#Connect From Your Local Machine to the LHM Sandbox|Connect From Your Local Machine to the LHM Sandbox]] below for more information
on using ''ssh'' and ''scp''.

====General Usage Notes====

1. The Linux Hadoop Minimal includes the following Apache software. Note: Spark 1.6.3 is installed because later versions need Python 2.7+ (not available in CentOS)\\
<code>
CentOS Linux 6.9 minimal
Apache Hadoop 2.8.1
Apache Pig 0.17.0
Apache Hive 2.3.2
Apache Spark 1.6.3
Apache Derby 10.13.1.1
Apache Zeppelin 0.7.3
Apache Sqoop-1.4.7
Apache Flume-1.8.0
</code>

2. The Linux Hadoop Minimal has been tested with VirtualBox on Linux, MacOS 10.12, and Windows 10 Home addition. It has not been tested with VMware.

3. The Linux Hadoop Minimal Virtual Machine is designed to work on minimal hardware. It is recommended at a MINIMUM your system have 2 cores, 4 GB memory, and 70G of disk space. The VM is set to use 2.5G of memory. This will cause some applications to swap to disk, but it should allow the virtual machine to run on a 4GB laptop/desktop. (If you are thinking of using the Hortonworks sandbox then 4+ cores and 16+ GB of memory is recommended)

4. The above packages have not been fully tested although all of the examples from the course should work.

====Installation Steps====

**Step 1:** Download and install VirtualBox for your environment. VirtualBox is freely available. Note: Some windows environments may need the Extension Pack. See the [[https://www.virtualbox.org|Virtual Box Web Page]].

**Step 2:** Follow the installation instructions for your Operating System environment. For Red Hat based systems this page, https://tecadmin.net/install-oracle-virtualbox-on-centos-redhat-and-fedora, is helpful. With Linux there is some dependencies on kernel versions and modules that need to be addressed.\\
If you are using Windows, you will need an "ssh client." Either of these will work. They are both freely available at no cost. (MobaXterm is recommended)\\

    * [[http://www.putty.org|Putty]] (provides terminal for ssh session)\\
    * [[http://mobaxterm.mobatek.net|MobaXterm]] (provides terminal for ssh sessions and allows remote X Windows session)

**Step 3:** Make sure hardware virtualization is enabled in your BIOS.

**Step 4:** Download the https://www.clustermonkey.net/download/Hands-on_Hadoop_Spark/Linux-Hadoop-Minimal-0.42.ova image and load it into VirtualBox. (NOTE newer version may be available.)


**Step 5:** Start the VM. All the essential Hadoop service should be started automatically.


====Connect From Your Local Machine to the LHM Sandbox====

It is possible to login and use the sandbox from the VirtualBox terminal, however, you will have much
more flexibility with local terminals. Follow the instructions below for local terminal access.

As a test, open a text terminal and connect to the sandbox as the root user with ''ssh''. Macintosh and
Linux machines have ''ssh'' and terminal installed, for windows see above (Putty or MobaXterm) or this document:

  * [[https://www.clustermonkey.net/download/Hands-on_Hadoop_Spark/DOS-Linux-HDFS-cheatsheet.pdf|DOS Linux HDFS Cheatsheet]]
  
The root password is: **hadoop**

  ssh root@127.0.0.1 -p 2222

You are should now be in the ''/root'' directory

To confirm all the Hadoop daemons have started enter ''jps'' as root The results should list the 10 daemons as shown below. (process numbers will be different) 

<code>
# jps
1938 NetworkServerControl
2036 ZeppelinServer
1797 ResourceManager
1510 NameNode
1973 RunJar
1576 SecondaryNameNode
1882 JobHistoryServer
1675 DataNode
1962 RunJar
1841 NodeManager
2445 Jps
</code>

====Copying Files In and Out of the Virtual Machine====

To copy a file from your LOCAL MACHINE into the VM, use the ''scp'' command. For instance, to copy the file ''SOURCE-FILE'' from your local directory on your ''LOCAL MACHINE'' to the "**hands-on**" account. The password is "**minimal**" and the command places file in ''/home/hands-on'' directory in the VM.

  scp -P2222  SOURCE-FILE  hands-on@127.0.0.1:/home/hands-on

To be clear, the above command is run on your ''LOCAL MACHINE''. On Macintosh and Linux systems run this from a terminal. On Windows run it from MobaXterm.

To copy a file from the VM to your ''LOCAL MACHINE'' and place it in your current directory use the following. (don't forget the ''.''):

  scp -P2222 hands-on@127.0.0.1:/home/hands-on/SOURCE-FILE .

To be clear, the above command is run on your ''LOCAL MACHINE''.

On Windows, the data will be placed in the MobaXterm "Persistent Home Directory." In the case of Windows 10 with user "Doug" this would be the following:

  C:\Users\Doug\Documents\MobaXterm\home

====Adding Users====

As configured, the LHM comes with one general user account. The account is called **hands-on** and the password is **minimal**. **It is highly recommended that this account be used for the class examples.** Remember you need to be user ''hdfs'' to do any administrative work in HDFS and running as user ''hdfs'' gives you full ''root'' control of the HDFS file system. The ''hdfs'' account has no active password. To become the ''hdfs'' user, log in as root and issue a ''su - hdfs'' command.

To add yourself as a user with a different user name follow the following steps.

**Step 1.** As root do the following to create a user and add a password:

<code>
useradd -G hadoop USERNAME
passwd USERNAME
</code>

**Step 2.** These steps change to user hdfs and create the user directory in HDFS (as root)

<code>
su - hdfs
hdfs dfs -mkdir /user/USERNAME
hdfs dfs -chown USERNAME:hadoop /user/USERNAME
exit
</code>

**Step 3.** Logout and login to the new account

====Web Access====

The various web interfaces shown in class are available using the following URLs. Enter the desired
URL in you local browser and the VM should respond.
<code>
HDFS web interface:       http://127.0.0.1:50070
YARN Jobs web Interface:  http://127.0.0.1:8088
Zeppelin Web Notebook:    http://127.0.0.1:9995
</code>

The Zeppelin interface is not configured (i.e. it is run in anonymous mode without the need to log-in).
The "Zeppelin Tutorial/Basic Features" notebook used in class works as does some of the ''SparkR''notebooks.

The ''PySpark Example'' that was demonstrated in class also works. Also, the ''md'' and ''sh'' interpreters have been tested and work.

==== Getting Data into Zeppelin====

If you want to load you own data into a Zeppelin notebook, place the data in the zeppelin account under ''/home/zeppelin''. Login as root to place data in this account then change the ownership to zeppelin user for example:

  # cp DATA /home/zeppelin
  # chown zeppelin:hadoop /home/zeppelin/DATA

This location is the default path for the Zeppelin interpreter (run ''pwd'' in the ''%sh'' interpreter).

==== Database for Sqoop Example====

MySQL has been installed in the VM. The World database used in the Sqoop example from the class
has been preloaded into MySQL. SQL login and password for the Sqoop database is **sqoop** and **sqoop**

====Log Files====

There is currently no logfile management and log directly may fill up and use the sandbox storage.
There is a ''clean-logs.sh'' script in ''/root/Hadoop-Minimal-Install-Notes/Hadoop-Pig-Hive/scripts''
This script will remove most of the Hadoop/Spark and system logs (somewhat aggressive)

=====Stopping and Starting the Hadoop Daemons=====

The Hadoop Daemons are started in the ''/etc/rc.local'' file (the last script file that
is run when the system boots) The actual scripts are in ''/usr/sbin'' and are very
simple with no checking. If you are knowledgeable, you can check ''/var/log/boot.log''
for errors and issues. The scripts are run in the following order:

  /usr/sbin/start-hdfs.sh
  /usr/sbin/start-yarn.sh
  /usr/sbin/start-derby.sh
  /usr/sbin/start-hive-metastore.sh
  /usr/sbin/start-hiveserver2.sh
  /usr/sbin/start-zeppelin.sh

A corresponding "stop script" is run when the system is shutdown or rebooted.

As mentioned, if all the the scripts are running, the ''jps'' command
(run as root) should show the following (process numbers will be different).
The RunJar entrees are for the ''hiveserver2'' and ''hive-metastore'' processes.

  # jps
  1938 NetworkServerControl
  2036 ZeppelinServer
  1797 ResourceManager
  1510 NameNode
  1973 RunJar
  1576 SecondaryNameNode
  1882 JobHistoryServer
  1675 DataNode
  1962 RunJar
  1841 NodeManager
  2445 Jps

For HDFS to be running correctly the following daemons need to be running:

  NameNode
  SecondaryNameNode
  DataNode

If one or all are not running, run (as root)

  /usr/sbin/stop-hdfs.sh
  /usr/sbin/start-hdfs.sh

For YARN to be running correctly the following daemons need to be running:

  ResourceManager
  JobHistoryServer
  NodeManager

If one or all are not running, run (as root)

  /usr/sbin/stop-yarn.sh
  /usr/sbin/start-yarn.sh

A local metadata database (called Derby) is needed for Hive, if
the ''NetworkServerControl'' daemon is not running, then stop and restart
the derby daemon:

  /usr/sbin/stop-derby.sh
  /usr/sbin/start-derby.sh

Spark can use Hive tables through a hive-metastore and hiveserver2 service. To stop and restart the services (in the following order)

  /usr/sbin/stop-hiveserver2.sh
  /usr/sbin/stop-hive-metastore.sh
  /usr/sbin/start-hive-metastore.sh
  /usr/sbin/start-hiveserver2.sh

Finally, if the Zeppelin web page cannot be reached, the Zeppelin daemon
may no be running. Stop and restart the daemon:

  /usr/sbin/stop-zeppelin.sh
  /usr/sbin/start-zeppelin.sh

If any or all of the daemons will not start after the above procedure
then the is a bigger issue with the VM. Please contact Eadline
and describe the situation.

When the VM is stopped (see below) with ''poweroff'' or restarted with ''reboot'' commands, a script called ''/sbin/halt.local'' shuts down all the daemons. 

====Stopping the VM====
To stop the VM, click on "machine" in the VirtualBox menu bar. Select "Close" and then
select the "Save State" option. The next time the machine starts it will have all the
changes you made.

Alternatively, you can enter (as root user) from within the VM:

  # poweroff

And the VM will gracefully shutdown the Hadoop/Spark services and preserve any changes you made.


====VM Installation Documentation====

Please see ''/root/Hadoop-Minimal-Install-Notes'' directory in the VM for how the packages were installed.

====Issues/Bugs====

These issues have been addressed in the current version of the VM. Please use the lasted VM and you can avoid these issues.

1. If you have problems loading the OVA image into VirtualBox, check the MD5 signature of the OVA file. The MD5 signature returned by running the program below should match the signature provided [[https://www.clustermonkey.net/download/Hands-on_Hadoop_Spark/Linux-Hadoop-Minimal-0.42.MD5.txt|here]]. For each OS, use the following commands (note the name of the OVA file may be different):

For **Linux** use "md5sum"

  $ md5sum Linux-Hadoop-Minimal-0.42.ova

For **Macintosh** use "md5"

  $ md5 Linux-Hadoop-Minimal-0.42.ova

For **Windows 10** (in PowerShell) use "Get-FileHash" (Also, note the use of uppercase)

  C:\Users\Doug> Get-FileHash .\Linux-Hadoop-Minimal-0.42.ova -Algorithm MD5

2. Either create your own user account as described above or use the existing "hands-on" user account. The examples will not work if run as the root account.

3. If zip is not installed on your version of the VM, you can install it by entering the following, as root, and a "y" when asked. Zip will now be installed and available for use.

   # yum install zip
   Loaded plugins: fastestmirror
   Setting up Install Process
   [...TEXT ...]
   Total download size: 259 k
   Installed size: 804 k
   Is this ok [y/N]: y
   [...TEXT ...]
   Installed:
     zip.x86_64 0:3.0-1.el6_7.1
     
4. In previous versions there is a permission issue in HDFS that prevents Hive jobs from working. To fix it, perform the following steps:

a) login to the VM as root (pw="hadoop")

     ssh root@127.0.0.1 -p 2222

b) then change to hdfs user

     su - hdfs

c) fix the permission error:

     hdfs dfs -chmod o+w /user/hive/warehouse

d) Check the result

     hdfs dfs -ls /user/hive

e) The output of the previous command should look like:

     Found 1 items
     drwxrwxrwx   - hive hadoop          0 2019-01-24 20:43 /user/hive/warehouse

f) Exit out of the hdfs account

     exit

g) exit out the root account

     exit

You should now be back at the terminal on your laptop/desktop
Live On-Line Training: Scalable Data Pipelines with Hadoop, Spark, and Kafka

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Live On-Line Training:
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