Apache Oozie Essentials

3.5 (2 reviews total)
By Jagat Jasjit Singh
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About this book

As more and more organizations are discovering the use of big data analytics, interest in platforms that provide storage, computation, and analytic capabilities is booming exponentially. This calls for data management. Hadoop caters to this need. Oozie fulfils this necessity for a scheduler for a Hadoop job by acting as a cron to better analyze data.

Apache Oozie Essentials starts off with the basics right from installing and configuring Oozie from source code on your Hadoop cluster to managing your complex clusters. You will learn how to create data ingestion and machine learning workflows.

This book is sprinkled with the examples and exercises to help you take your big data learning to the next level. You will discover how to write workflows to run your MapReduce, Pig ,Hive, and Sqoop scripts and schedule them to run at a specific time or for a specific business requirement using a coordinator. This book has engaging real-life exercises and examples to get you in the thick of things. Lastly, you’ll get a grip of how to embed Spark jobs, which can be used to run your machine learning models on Hadoop.

By the end of the book, you will have a good knowledge of Apache Oozie. You will be capable of using Oozie to handle large Hadoop workflows and even improve the availability of your Hadoop environment.

Publication date:
December 2015
Publisher
Packt
Pages
164
ISBN
9781785880384

 

Chapter 1. Setting up Oozie

Oozie is a workflow scheduler system to run Apache Hadoop jobs. Oozie Workflow jobs are Directed Acyclic Graphs (DAGs) of actions. More information on DAG can be found at https://en.wikipedia.org/wiki/Directed_acyclic_graph. Actions tell what to do in the job. Oozie supports running jobs of various types such as Java, Map-reduce, Pig, Hive, Sqoop, Spark, and Distcp. The output of one action can be consumed by the next action to create a chain sequence.

Oozie has client-server architecture, in which we install the server for storing the jobs and using client we submit our jobs to the server.

In this chapter, we will learn how to install Oozie for learning purpose and in production. For learning purposes, we will build Oozie from the source code, and for production we will use Hadoop distribution by Hortonworks. Throughout the book, we will use Hortonworks single node virtual machine. If you are using a different Hadoop distribution, you should not worry at all. All distribution packages are the same for Oozie software, which is made by the Apache community (http://oozie.apache.org).

After reading this chapter, we will be able to:

  • Configure Oozie in Hortonworks distribution using Ambari

  • Install Oozie using the source code provided as tar ball by the Apache Oozie website

 

Configuring Oozie in Hortonworks distribution


In this section, we will learn how to configure Oozie inside Hortonworks Hadoop distribution using Ambari. We will configure the Oozie server to use a MySQL database instead of the default Derby database to store all job information.

We will use a virtual machine to learn how to configure Oozie in Hortonworks Hadoop distribution. Most of other distributions, such as Cloudera, Pivotal, and so on, have similar steps.

Let's start with the following steps:

  1. If you don't have VirtualBox on your machine, then download and install VirtualBox from https://www.virtualbox.org/wiki/Downloads.

  2. Download the Hortonworks single node virtual machine from http://hortonworks.com/hdp/downloads/. It will take 1-2 hours depending upon your Internet connection speed.

    Tip

    It is always good to store the virtual machine images in a common folder. For example, I have folder in my machine such as ~/dev/vm/. It makes virtual machine image management easier.

  3. After the download is complete, open the VirtualBox and click on File | Import Appliance:

    Import appliance

  4. Click on the Import Appliance button, browse to the place where you downloaded the virtual machine image, and then click on Continue.

  5. Wait till the VirtualBox imports the new machine.

  6. Once you can see the machine is imported, click on Start machine in the virtual machine console.

  7. On completion of boot process of the machine, you can log in to the Ambari dashboard by opening the URL http://127.0.0.1:8080 in your browser.

  8. Use the username as well as password as admin.

    It will take some time for all services to start up and report their status to Ambari. Once the system has reported the status, all services have a glance at the Ambari console. It is also a good idea to stop the services which we are not using to reduce the load on the system.

  9. In the Ambari dashboard, click on the link named Oozie on the left side. You can see there are two components for Oozie, Oozie Server and Oozie Client. Since we are using a single node cluster, we have both the server and client installed on the same machine. In the production environment, you will configure the Oozie server and clients separately on different machines. Using the client, we will submit the jobs to server. Before submitting the job, we will tell where the server is located using the OOZIE_URL variable.

    Tip

    To save time in manually specifying the Oozie server on the client machine every time, you can set the environment variable OOZIE_URL in your bash_profile or environment file depending on the operating system you use. You should say export OOZIE_URL=http://oozieserver:11000/oozie; in this book oozieserver will be localhost.

  10. Now click on the Config link at the top and we will configure the database as MySQL. The Oozie server will use MySQL to store the job information:

    Ambari Oozie configuration

  11. You may notice, at this moment, the server has been configured to use a Derby database. Derby is good for playing and testing, but not for running the production sever. We will configure it to use a MySQL-based database.

  12. Log in to the virtual machine using SSH as follows:

    $ ssh root@127.0.0.1 -p 2222
    

    The default password is hadoop.

  13. After you log in to the SSH session, log in to MySQL:

    $ mysql -u root
    
  14. Since this is a test virtual machine, the password is not configured. In production, you will be having password protection.

  15. At the MySQL prompt, execute the following SQL statements:

    CREATE USER 'oozie'@'%' IDENTIFIED BY 'hadoop';
    CREATE DATABASE oozie;
    GRANT ALL PRIVILEGES ON oozie.* TO 'oozie'@'%' WITH GRANT OPTION;
    

    The following output will be generated:

    Oozie database creation

  16. To make Oozie work with MySQL, we need to get driver for it. Let's download the MySQL JDBC driver from the MySQL JDBC jar download section. Extract the jar to a folder such as /root/mysql inside the virtual machine:

    $ cd ~/
    $ mkdir mysql
    $ cd mysql
    $ # Download the MySQL JDBC Driver
    $ wget http://dev.mysql.com/get/Downloads/Connector-J/mysql-connector-java-5.1.36.tar.gz
    $ # Extract tar
    $ tar -xvf mysql-connector-java-5.1.36.tar.gz
    $ # Tell Ambari that we got new MYSQL JDBC driver which it can use
    $ ambari-server setup --jdbc-db=mysql --jdbc-driver=/root/mysql/mysql-connector-java-5.1.36/mysql-connector-java-5.1.36-bin.jar
    
  17. In the Ambari dashboard, configure the MySQL database with the following details:

    Field name

    Value

    Database Name

    oozie

    Database Username

    oozie

    Database Password

    hadoop

    JDBC Driver Class

    com.mysql.jdbc.Driver

    JDBC Database URL

    jdbc:mysql://localhost:3306/${oozie.db.schema.name}?createDatabaseIfNotExist=true

  18. In the Ambari dashboard page, click on Test Connection. If all is good, there should be a green tick. So, we have now configured the Oozie server to use MySQL database instead of Derby.

  19. Finally, to confirm that Oozie works properly, in another browser tab open the Oozie dashboard by entering the URL http://127.0.0.1:11000/oozie.

This completes the first section in which we learned how to configure Oozie for Hortonworks Ambari distribution.

 

Installing Oozie using tar ball


In this section, we will learn how to build and install Oozie from the source code. Since Hortonworks virtual machine had already Oozie installed, we did not need to do anything.

Just to learn how to install Oozie from tar ball in this section, we will use a Vagrant-based machine in which we will configure and install the Oozie server.

The summary of the steps we will perform is as follows:

  1. Create a test build machine.

  2. Download and build the Oozie code to make a WAR file.

  3. Download the Oozie third-party dependency jars and libraries.

  4. Package the Oozie WAR file and its dependencies into a WAR file.

  5. Configure the MySQL database for the Oozie server.

  6. Configure the shared library.

  7. Start and test the Oozie server.

Note

Just as a heads-up, the vagrant machine needs lot of resources to build the code. So, if you do not have a powerful machine, you can build it directly on your host operating system rather than the virtual machine. I am working on a MacBook Pro, which has a 16 GB RAM. I gave 8 GB to the virtual machine to show how to install Oozie from source.

Creating a test virtual machine

The following are the steps to create a test virtual machine:

  1. Download latest Oozie distribution from the Apache Oozie website. Go to the downloads section and download the latest version (4.2.0 at time of writing) in machine where you want to install it.

  2. Download and install Vagrant depending upon your operating system:

    The Vagrant download

  3. After this, go to the VirtualBox website. Depending on your computer operating system, download and install the VirtualBox.

  4. If you already have a test machine that has a Linux-based operating system, then you can skip the Vagrant-based setup and follow the steps for building Oozie from scripts.

  5. Clone the source code for the book from https://github.com/jagatsingh/apache_oozie_essentials.git.

  6. Create a folder in your system called dev, or any suitable location where we can clone code. We will call the dev/apache_oozie_essentials location as <BOOK_CODE_HOME> in this book. The following are the commands to do this:

    $ git clone https://github.com/jagatsingh/apache_oozie_essentials.git
    $ cd <BOOK_CODE_HOME>
    $ cd learn_oozie/ch01
    $ # Let's start the virtual machine
    $ vagrant up
    
  7. Wait for some time till our new test machine comes up.

    Here is what Vagrant does behind the scene:

    • Gets the image of the Centos 6.5 operating system

    • Installs JDK, MySQL, Git, and Maven

  8. All the preceding steps are being done by the provider script, which is shown as follows:

    $ sudo wget http://repos.fedorapeople.org/repos/dchen/apache-maven/epel-apache-maven.repo -O /etc/yum.repos.d/epel-apache-maven.repo
    $ sudo yum install -y java-1.7.0-openjdk mysql-server git unzip zip apache-maven telnet
    $ cp /vagrant/files/maven/settings.xml /etc/maven/
    $ sudo service mysqld start
    
  9. When the machine starts off completely, you will see something, as shown in the following figure:

    Vagrant up finish

    If you need a quick tutorial on how Vagrant works, then read the documentation on Vagrant at https://docs.vagrantup.com/v2/.

  10. Now we can log in to the virtual machine by using the command vagrant ssh. This command should be executed from the folder ch01.

  11. Inside the Vagrant virtual machine, mount/vagrant is same as the ch01 folder, placed at <BOOK_CODE_HOME>/learn_oozie/, from where we started the Vagrant.

    $ cd /vagrant
    $ ls
    

Building Oozie source code

Let's build Oozie from the source code. We will download the latest Oozie distribution and build it. All of these steps are present in the script build_oozie.sh placed at cat/vagrant/scripts/.

The contents of the script which we will run is as follows:

# Download and make Oozie distribution
$ cd ~/
$ mkdir {oozie_build,oozie_install,hadoop_install}
$ cd oozie_build
$ wget http://apache.mirror.digitalpacific.com.au/oozie/4.2.0/oozie-4.2.0.tar.gz
$ tar -xvf oozie-4.2.0.tar.gz
$ cd oozie-4.2.0
$ bin/mkdistro.sh -DskipTests -P hadoop-2

Summary of the build script

In the oozie_build directory, we will build Oozie. In the oozie_install directory, we will install Oozie. In the hadoop_install directory, we will download Hadoop distribution and copy few jars needed for Oozie to run. You can also download the jars from your own hadoop cluster.

Let's run the command to start the Oozie build. It will take some time to download all the dependencies and build the source code:

$ /vagrant/scripts/build_oozie.sh

Tip

If you already have a Maven repository on your host machine and want to to avoid downloading maven artifacts again, then look at the Maven settings file. I have configured (and commented) it to use my MacBook home maven as I already had all the artifacts there. You can uncomment that if you want to do something similar.

Codehaus Maven move

Codehaus no longer serves up Maven repositories, we need to configure Maven to download those dependencies from a different location. If you look at /etc/maven/settings.xml, which came with this machine, it has already been modified. You can see the details about it on the Codehaus website at http://www.codehaus.org/mechanics/maven/.

On a successful build, you should see something like the following screenshot:

Oozie build success

Download dependency jars

To run Oozie properly, the Oozie WAR file needs to have some dependencies packaged with it. Some of them are Hadoop, MySQL JDBC driver, Ext-js, and so on. The MySQL JDBC driver is used by the server database, and Ext-js is used by the Oozie web console.

We will copy all of them in to one folder, libext, and then use the oozie-setup.sh command to build the WAR file.

Let's download the Hadoop jars from your cluster or by executing the following steps:

$ cd ~/hadoop_install
$ wget https://archive.apache.org/dist/hadoop/common/hadoop-2.4.0/hadoop-2.4.0.tar.gz
$ tar -xvf hadoop-2.4.0.tar.gz

Now we should have Hadoop extracted to the folder ~/hadoop_install.

The preceding steps can be executed in one go using the following command:

/vagrant/scripts/download_hadoop_jars.sh

Preparing to create a WAR file

To create the WAR file, we need to copy the Oozie distro built earlier and combine it with the jars for Hadoop, the MySQL JDBC driver, and the Ext-js library.

If you remember from the previous Ambari Oozie configuration, we used MySQL as our database and configured it using the ambari-setup command. We will take a similar approach for the MySQL JDBC driver jar, which we are providing by merging it with the Oozie WAR file.

Let's prepare the Oozie distro using the following commands:

# Prepare to make Oozie war file
$ cd ~/oozie_install
$ cp ~/oozie_build/oozie-4.2.0/distro/target/oozie-4.2.0-distro.tar.gz ~/oozie_install
$ tar -xvf oozie-4.2.0-distro.tar.gz
$ cd oozie-4.2.0
$ # Removing hsql jar as they cause class conflict
$ rm lib/hsqldb-1.8.0.10.jar

Download the MySQL jar using the following commands:

# Collect all external jar files
$ mkdir libext
$ wget https://dev.mysql.com/get/Downloads/Connector-J/mysql-connector-java-5.1.36.tar.gz --no-check-certificate
$ tar -xvf mysql-connector-java-5.1.36.tar.gz
$ # Copy MySQL JDBC Driver
$ cp mysql-connector-java-5.1.36/*.jar libext/

Merge the Hadoop jars and the ext-js library using the following commands:

$ cd libext
$ wget http://dev.sencha.com/deploy/ext-2.2.zip
$ # Collect hadoop related jars
$ shopt -s globstar
$ /bin/cp -rf ~/hadoop_install/hadoop-2.4.0/share/**/*.jar ~/oozie_install/oozie-4.2.0/libext
$ # Removing source jars to reduce size
$ rm -rf *sources*
$ rm -rf *jasper*

All of the preceding steps can be executed in one go using the following command:

/vagrant/scripts/war_file_preparation.sh

After successful execution, go to /home/vagrant/oozie_install/oozie-4.2.0/libext and see that we now have jars placed in the folder.

Create a WAR file

Now we need to package the oozie-distro and jars that we copied in to the libext folder as a single packaged WAR file. This WAR file will be deployed in tomcat by going to the folder /home/vagrant/oozie_install/oozie-4.2.0 and executing the following command:

bin/oozie-setup.sh prepare-war

The command completes with a WAR file being created in the folder, as shown in the following screenshot:

Prepare a WAR file

Note

Exercise: Execute bin/oozie-setup.sh help and read all the commands possible with the setup command.

Configure Oozie MySQL database

If you remember, we configured Ambari Oozie to use MySQL database for Oozie. We will do the same for this instance of the Oozie server.

At the Mysql prompt, execute the following:

$ mysql -u root
CREATE USER 'oozie'@'%' IDENTIFIED BY 'hadoop';
CREATE DATABASE oozie;
GRANT ALL PRIVILEGES ON oozie.* TO 'oozie'@'%' WITH GRANT OPTION;

This will create the Oozie database, which will be used by the server.

Go to /home/vagrant/oozie_install/oozie-4.2.0/conf and open the oozie-site.xml file. In this file, all the Oozie settings are declared. All the Oozie configuration properties and their default values are defined in the oozie-default.xml file.

Oozie resolves configuration property values in the following order.

If a Java System property is defined, it uses its value, else if the Oozie configuration file (oozie-site.xml) contains the property, it uses its value, else it uses the default value documented in the oozie-default.xml file.

Note

Oozie does not use the oozie-default.xml file found in the conf/ directory. It is there for reference purposes only.

Let's edit the oozie-site.xml and configure the database details. You can use the vi editor or copy the settings from the already created file using the following command:

$ cp /vagrant/files/oozie/oozie-site.xml /home/vagrant/oozie_install/oozie-4.2.0/conf/

If you want to edit it manually, then add the following code:

<property>
  <name>oozie.service.JPAService.jdbc.driver</name>
  <value>com.mysql.jdbc.Driver</value>
  <description>JDBC driver class</description>
</property>
<property>
  <name>oozie.service.JPAService.jdbc.url</name>
  <value>jdbc:mysql://localhost:3306/${oozie.db.schema.name}?createDatabaseIfNotExist=true</value>
  <description>JDBC URL</description>
</property>
<property>
  <name>oozie.service.JPAService.jdbc.username</name>
  <value>oozie</value>
  <description>DB user name</description>
</property>
<property>
  <name>oozie.service.JPAService.jdbc.password</name>
  <value>hadoop</value>
  <description>DB user password</description>
</property>

Note

Exercise: Execute bin/ooziedb.sh help and read all the commands possible with the setup command.

Let's create the database tables in our newly created database using the following command:

bin/ooziedb.sh create -sqlfile oozie.sql -run

The following screenshot shows the output generated:

Database creation success

Configure the shared library

We just need to tell Oozie about the shared libraries before starting the Oozie server. The Oozie sharelib .tar.gz file bundled with the distribution contains the necessary files to run Oozie Map-reduce streaming, Pig, Hive, Sqoop, Hcatalog, and Distcp actions.

Let's execute the following command:

bin/oozie-setup.sh sharelib create -fs oozie-sharelib-4.2.0.tar.gz

The following screenshot shows the output generated:

Create a shared library

Start server testing and verification

The following command is used to start the server:

bin/oozied.sh start

Note

Exercise: Execute bin/oozied.sh help and read all the commands possible with the setup command.

The command, on successful completion, will not print any error message. We can check the status of Oozie server using the following command:

bin/oozie admin -oozie http://localhost:11000/oozie -status

The output should be:

system mode: NORMAL

We can also check the Oozie web console by opening the URL http://localhost:11000/oozie.

 

Summary


We started this chapter with the configuration of Oozie inside the Hortonworks virtual machine. We learned how to configure the database for Oozie. Then we started building Oozie from the source code. We packaged the WAR file and also configured the MySQL database.

This completes the installation for the Oozie server.

In the next chapter, we will run our first Oozie job. We will learn how to run Hadoop filesystem commands in Oozie. We will also install Hue and create our Workflow using the editor provided by it.

About the Author
  • Jagat Jasjit Singh

    Jagat Jasjit Singh works for one of the largest telecom companies in Melbourne, Australia, as a big data architect. He has a total experience of over 10 years and has been working with the Hadoop ecosystem for more than 5 years. He is skilled in Hadoop, Spark, Oozie, Hive, Pig, Scala, machine learning, HBase, Falcon, Kakfa, GraphX, Flume, Knox, Sqoop, Mesos, Marathon, Chronos, Openstack, and Java. He has experience of a variety of Australian and European customer implementations. He actively writes on Big Data and IoT technologies on his personal blog (http://jugnu.life). Jugnu (a Punjabi word) is a firefly that glows at night and illuminates the world with its tiny light. Jagat believes in this same philosophy of sharing knowledge to make the world a better place. You can connect with him on LinkedIn at https://au.linkedin.com/in/jagatsingh.

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