How to Install and Configure Hadoop on Ubuntu 20.04

Hadoop is a free, open-source, and Java-based software framework used for the storage and processing of large datasets on clusters of machines. It uses HDFS to store its data and process these data using MapReduce. It is an ecosystem of Big Data tools that are primarily used for data mining and machine learning.

Apache Hadoop 3.3 comes with noticeable improvements and many bug fixes over the previous releases. It has four major components such as Hadoop Common, HDFS, YARN, and MapReduce.

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This tutorial will explain you to how to install and configure Apache Hadoop on Ubuntu 20.04 LTS Linux system.

Step 1 – Installing Java

Hadoop is written in Java and supports only Java version 8. Hadoop version 3.3 and the latest also support Java 11 runtime as well as Java 8.

You can install OpenJDK 11 from the default apt repositories:

sudo apt update 
sudo apt install openjdk-11-jdk

Once installed, verify the installed version of Java with the following command:

java -version 

You should get the following output:

openjdk version "11.0.11" 2021-04-20
OpenJDK Runtime Environment (build 11.0.11+9-Ubuntu-0ubuntu2.20.04)
OpenJDK 64-Bit Server VM (build 11.0.11+9-Ubuntu-0ubuntu2.20.04, mixed mode, sharing)

Step 2 – Create a Hadoop User

It is a good idea to create a separate user to run Hadoop for security reasons.

Run the following command to create a new user with name hadoop:

sudo adduser hadoop 

Provide and confirm the new password as shown below:

Adding user `hadoop' ...
Adding new group `hadoop' (1002) ...
Adding new user `hadoop' (1002) with group `hadoop' ...
Creating home directory `/home/hadoop' ...
Copying files from `/etc/skel' ...
New password:
Retype new password:
passwd: password updated successfully
Changing the user information for hadoop
Enter the new value, or press ENTER for the default
        Full Name []:
        Room Number []:
        Work Phone []:
        Home Phone []:
        Other []:
Is the information correct? [Y/n] y

Step 3 – Configure SSH Key-based Authentication

Next, you will need to configure passwordless SSH authentication for the local system.

First, change the user to hadoop with the following command:

su - hadoop 

Next, run the following command to generate Public and Private Key Pairs:

ssh-keygen -t rsa 

You will be asked to enter the filename. Just press Enter to complete the process:

Generating public/private rsa key pair.
Enter file in which to save the key (/home/hadoop/.ssh/id_rsa):
Created directory '/home/hadoop/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/hadoop/.ssh/id_rsa
Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub
The key fingerprint is:
SHA256:QSa2syeISwP0hD+UXxxi0j9MSOrjKDGIbkfbM3ejyIk hadoop@ubuntu20
The key's randomart image is:
+---[RSA 3072]----+
| ..o++=.+        |
|..oo++.O         |
|. oo. B .        |
|o..+ o * .       |
|= ++o o S        |
|.++o+  o         |
|.+.+ + . o       |
|o . o * o .      |
|   E + .         |
+----[SHA256]-----+

Next, append the generated public keys from id_rsa.pub to authorized_keys and set proper permission:

cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys 
chmod 640 ~/.ssh/authorized_keys 

Next, verify the passwordless SSH authentication with the following command:

ssh localhost 

You will be asked to authenticate hosts by adding RSA keys to known hosts. Type yes and hit Enter to authenticate the localhost:

The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:JFqDVbM3zTPhUPgD5oMJ4ClviH6tzIRZ2GD3BdNqGMQ.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes

Step 4 – Installing Hadoop

First, change the user to hadoop with the following command:

su - hadoop 

Next, download the latest version of Hadoop using the wget command:

wget https://downloads.apache.org/hadoop/common/hadoop-3.3.0/hadoop-3.3.0.tar.gz 

Once downloaded, extract the downloaded file:

tar -xvzf hadoop-3.3.0.tar.gz 

Next, rename the extracted directory to hadoop:

mv hadoop-3.3.0 hadoop 

Next, you will need to configure Hadoop and Java Environment Variables on your system.

Open the ~/.bashrc file in your favorite text editor:

nano ~/.bashrc 

Append the below lines to file. You can find JAVA_HOME location by running dirname $(dirname $(readlink -f $(which java))) command on terminal.

export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
export HADOOP_HOME=/home/hadoop/hadoop
export HADOOP_INSTALL=$HADOOP_HOME
export HADOOP_MAPRED_HOME=$HADOOP_HOME
export HADOOP_COMMON_HOME=$HADOOP_HOME
export HADOOP_HDFS_HOME=$HADOOP_HOME
export HADOOP_YARN_HOME=$HADOOP_HOME
export HADOOP_COMMON_LIB_NATIVE_DIR=$HADOOP_HOME/lib/native
export PATH=$PATH:$HADOOP_HOME/sbin:$HADOOP_HOME/bin
export HADOOP_OPTS="-Djava.library.path=$HADOOP_HOME/lib/native"

Save and close the file. Then, activate the environment variables with the following command:

source ~/.bashrc 

Next, open the Hadoop environment variable file:

nano $HADOOP_HOME/etc/hadoop/hadoop-env.sh 

Again set the JAVA_HOME in the Hadoop environment.

export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64

Save and close the file when you are finished.

Step 5 – Configuring Hadoop

First, you will need to create the namenode and datanode directories inside Hadoop home directory:

Run the following command to create both directories:

mkdir -p ~/hadoopdata/hdfs/namenode 
mkdir -p ~/hadoopdata/hdfs/datanode 

Next, edit the core-site.xml file and update with your system hostname:

nano $HADOOP_HOME/etc/hadoop/core-site.xml 

Change the following name as per your system hostname:

Save and close the file. Then, edit the hdfs-site.xml file:

nano $HADOOP_HOME/etc/hadoop/hdfs-site.xml 

Change the NameNode and DataNode directory path as shown below:

Save and close the file. Then, edit the mapred-site.xml file:

nano $HADOOP_HOME/etc/hadoop/mapred-site.xml 

Make the following changes:

Save and close the file. Then, edit the yarn-site.xml file:

nano $HADOOP_HOME/etc/hadoop/yarn-site.xml 

Make the following changes:

Save and close the file when you are finished.

Step 6 – Start Hadoop Cluster

Before starting the Hadoop cluster. You will need to format the Namenode as a hadoop user.

Run the following command to format the Hadoop Namenode:

hdfs namenode -format 

You should get the following output:

2020-11-23 10:31:51,318 INFO namenode.NNStorageRetentionManager: Going to retain 1 images with txid >= 0
2020-11-23 10:31:51,323 INFO namenode.FSImage: FSImageSaver clean checkpoint: txid=0 when meet shutdown.
2020-11-23 10:31:51,323 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at hadoop.tecadmin.net/127.0.1.1
************************************************************/

After formatting the Namenode, run the following command to start the Hadoop cluster:

start-dfs.sh 

Once the HDFS started successfully, you should get the following output:

Starting namenodes on [hadoop.tecadmin.com]
hadoop.tecadmin.com: Warning: Permanently added 'hadoop.tecadmin.com,fe80::200:2dff:fe3a:26ca%eth0' (ECDSA) to the list of known hosts.
Starting datanodes
Starting secondary namenodes [hadoop.tecadmin.com]

Next, start the YARN service as shown below:

start-yarn.sh 

You should get the following output:

Starting resourcemanager
Starting nodemanagers

You can now check the status of all Hadoop services using the jps command:

jps 

You should see all the running services in the following output:

18194 NameNode
18822 NodeManager
17911 SecondaryNameNode
17720 DataNode
18669 ResourceManager
19151 Jps

Step 7 – Adjust Firewall

Hadoop is now starting and listening on ports 9870 and 8088. Next, you will need to allow these ports through the firewall.

Run the following command to allow Hadoop connections through the firewall:

firewall-cmd --permanent --add-port=9870/tcp 
firewall-cmd --permanent --add-port=8088/tcp 

Next, reload the firewalld service to apply the changes:

firewall-cmd --reload 

Step 8 – Access Hadoop Namenode and Resource Manager

To access the Namenode, open your web browser and visit the URL http://your-server-ip:9870. You should see the following screen:

http://hadoop.tecadmin.net:9870

To access Resource Manage, open your web browser and visit the URL http://your-server-ip:8088. You should see the following screen:

http://hadoop.tecadmin.net:8088

Step 9 – Verify the Hadoop Cluster

At this point, the Hadoop cluster is installed and configured. Next, we will create some directories in the HDFS filesystem to test the Hadoop.

Let’s create some directories in the HDFS filesystem using the following command:

hdfs dfs -mkdir /test1
hdfs dfs -mkdir /logs 

Next, run the following command to list the above directory:

hdfs dfs -ls / 

You should get the following output:

Found 3 items
drwxr-xr-x   - hadoop supergroup          0 2020-11-23 10:56 /logs
drwxr-xr-x   - hadoop supergroup          0 2020-11-23 10:51 /test1

Also, put some files to hadoop file system. For the example, putting log files from host machine to hadoop file system.

hdfs dfs -put /var/log/* /logs/  

You can also verify the above files and directory in the Hadoop Namenode web interface.

Go to the Namenode web interface, click on the Utilities => Browse the file system. You should see your directories which you have created earlier in the following screen:

http://hadoop.tecadmin.net:9870/explorer.html

Step 10 – Stop Hadoop Cluster

You can also stop the Hadoop Namenode and Yarn service any time by running the stop-dfs.sh and stop-yarn.sh script as a Hadoop user.

To stop the Hadoop Namenode service, run the following command as a hadoop user:

stop-dfs.sh  

To stop the Hadoop Resource Manager service, run the following command:

stop-yarn.sh 

Conclusion

This tutorial explained to you step-by-step tutorial to install and configure Hadoop on Ubuntu 20.04 Linux system.