Introduction

Elasticsearch is an open-sourced distributed search and analytics engine for all data types, including textual, numerical, and unstructured. Elasticsearch supports simple REST APIs to search and analyze data.

This article will explain how to install and configure elastic search on Centos 7.

Prerequisites

A root or non-root user with sudo privileges on a CentOS-7 system.

Install Java

Before Installing Elasticsearch you need to install Java on your system.

Install the latest version of Java on the system.
```
# sudo yum -y install java-11-openjdk-devel
```
Verify the installed Java version.
```
# java -version
```

Install Elasticsearch

First, install wget package if not installed on your system.
```
# sudo yum -y install wget
```

Download Elasticsearch rpm from the official repository.

# wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.9.2-x86_64.rpm

Install Elasticsearch using the rpm command.

# sudo rpm -ivh elasticsearch-7.9.2-x86_64.rpm

After successfully installation of Elasticsearch, enable it.
```
# sudo systemctl enable elasticsearch
```

Configuring Elasticsearch

Elasticsearch configuration files are located in/etc/elasticsearch by default, it listens on localhost only.

Open theelasticsearch.ymlconfiguration file.
```
# vi /etc/elasticsearch/elasticsearch.yml
```
Uncomment the cluster.name and node.name in the file and set the values for both attributes.
```
node.name: my-node
cluster.name: mycluster
```
Start the Elasticsearch services.
```
# sudo systemctl start elasticsearch
```
To test the service, make a GETrequest on your system.
```
# curl -X GET 'http://localhost:9200'
```

Use of Elasticsearch

Send a POSTrequest to the Elasticsearch server to the first entry in Elasticsearch.

# curl -H 'Content-Type: application/json' -X POST 'http://localhost:9200/data/firstentry/1' -d '{ "message": "Hello Test!"
}'

Retrieve your added entry using HTTP get request.

# curl -X GET 'http://localhost:9200/data/firstentry/1'