How to Install Elasticsearch on openSUSE Leap 15

Elasticsearch is a highly scalable open-source full-text search and analytics engine. It is generally the underlying engine/technology that powers applications with complex search features and requirements. The software supports RESTful operations that allow you to store, search, and analyze significant volumes of data quickly and in near real-time. Elasticsearch is well-liked and popular amongst sysadmins and developers as it is a mighty search engine based on the Lucene library.

In the following tutorial, you will learn how to install Elastic Search on openSUSE Leap 15.

Prerequisites

• Recommended OS: openSUSE Leap – 15.x 
• User account: A user account with sudo or root access.

Update Operating System

Update your openSUSE operating system to make sure all existing packages are up to date:

sudo zypper refresh

The tutorial will be using the sudo command and assuming you have sudo status.

To verify sudo status on your account:

sudo whoami

Example output showing sudo status:

[joshua@opensuse ~]$ sudo whoami
root

To set up an existing or new sudo account, visit our tutorial on adding a User to Sudoers on openSUSE.

To use the root account, use the following command with the root password to log in.

su

Install CURL Package

The CURL command is needed for some parts of this guide. To install this package, type the following command:

sudo zyper install curl

Install Java Package

To successfully install and, more importantly, use Elasticsearch, you need to install Java. The process is relatively easy.

Type the following command to install the OpenJDK package:

sudo zypper install java-11-openjdk-devel

Install Elasticsearch

Elasticsearch is not available in the standard openSUSE repository, so you need to install it from the Elasticsearch repository.

Before adding the repository, import the GPG key with the following command:

sudo rpm --import https://artifacts.elastic.co/GPG-KEY-elasticsearch

The next step is to create an Elasticsearch repo file as follows:

sudo zypper ar https://artifacts.elastic.co/packages/7.x/yum elasticsearch

Now Install Elasticsearch using the following command:

sudo zypper install elasticsearch

Example output:

Type “Y,” then press the “ENTER KEY” to proceed with the installation

To enable Elasticsearch to be enabled by default, you will need to install insserv package.

sudo zypper install insserv

By default, the Elasticsearch service is disabled on boot and not active. To start the service and enable it on system boot, type the following (systemctl) command:

sudo systemctl enable elasticsearch.service --now

Example output:

Synchronizing state of elasticsearch.service with SysV service script with /usr/lib/systemd/systemd-sysv-install.
Executing: /usr/lib/systemd/systemd-sysv-install enable elasticsearch

Verify that Elasticsearch is running correctly by using the curl command to send an HTTP request to port 9200 on localhost as follows:

sudo curl http://localhost:9200?pretty

Example output:

How to Configure Elasticsearch

Elasticsearch data is stored in the default directory location (/var/lib/elasticsearch). To view or edit the configuration files, you can find them in the directory location (/etc/elasticsearch), and java start-up options can be configured in the (/etc/default/elasticsearch) configuration file.

The default settings are primarily fine for single operating servers as Elasticsearch runs on localhost only. However, if you are going to set up a cluster, you will need to modify the configuration file to allow remote connections.

Set-up Remote Access (Optional)

By default, Elasticsearch listens only to localhost. To change this, open up the configuration file as follows:

sudo nano /etc/elasticsearch/elasticsearch.yml

Scroll down to line 56 and find the Network section and uncomment (#) the following line and replace it with the Internal Private IP address or External IP address as follows:

In the example, we uncommented (#) the (network.host) and changed it to an Internal Private IP address as above.

For security purposes, it is ideal for specifying addresses; however, if you have multiple Internal or External IP addresses hitting the server change the network interface to listen to all with entering (0.0.0.0) as follows:

Save the configuration file (CTRL+O), then exit (CLTR+X).

You will need to restart the Elasticsearch service with the following command for changes to take effect:

sudo systemctl restart elasticsearch

Configure Firewalld for Elasticsearch

By default, no rules are set up for Elasticsearch, which can cause issues down the track.

First, add a new dedicated zone for Elasticsearch firewalld policy:

sudo firewall-cmd --permanent --new-zone=elasticsearch

Next, specify the allowed IP addresses that are permitted to access the Memcached.

sudo firewall-cmd --permanent --zone=elasticsearch --add-source=1.2.3.4

Replace 1.2.3.4 with the IP address that will be added to the allow list.

Once you have finished adding the IP addresses, open the port of the Memcached.

For example, TCP port 11211.

sudo firewall-cmd --permanent --zone=elasticsearch --add-port=9200/tcp

Note, you can change the default port in your configuration file if you change the firewall port open rule above to the new value.

After running those commands, reload the firewall to implement the new rules:

sudo firewall-cmd --reload

Example output if successful:

success

How to Use Elasticsearch

To use Elasticsearch using the curl command is a straightforward process. Below are some of the most commonly used:

Delete index

Below the index is named samples.

curl -X DELETE 'http://localhost:9200/samples'

List all indexs

curl -X GET 'http://localhost:9200/_cat/indices?v'

List all docs in index

curl -X GET 'http://localhost:9200/sample/_search'

Query using URL parameters

Here we use Lucene query format to write q=school:Harvard.

curl -X GET http://localhost:9200/samples/_search?q=school:Harvard

Query with JSON aka Elasticsearch Query DSL

You can query using parameters on the URL. But you can also use JSON, as shown in the following example. JSON would be easier to read and debug when you have a complex query than one giant string of URL parameters.

curl -XGET --header 'Content-Type: application/json' http://localhost:9200/samples/_search -d '{
      "query" : {
        "match" : { "school": "Harvard" }
    }
}'

List index mapping

All Elasticsearch fields are indexes. So this lists all fields and their types in an index.

curl -X GET http://localhost:9200/samples

Add Data

curl -XPUT --header 'Content-Type: application/json' http://localhost:9200/samples/_doc/1 -d '{
   "school" : "Harvard"			
}'

Update Doc

Here is how to add fields to an existing document. First, we create a new one. Then we update it.

curl -XPUT --header 'Content-Type: application/json' http://localhost:9200/samples/_doc/2 -d '
{
    "school": "Clemson"
}'

curl -XPOST --header 'Content-Type: application/json' http://localhost:9200/samples/_doc/2/_update -d '{
"doc" : {
               "students": 50000}
}'

Backup index

curl -XPOST --header 'Content-Type: application/json' http://localhost:9200/_reindex -d '{
  "source": {
    "index": "samples"
  },
  "dest": {
    "index": "samples_backup"
  }
}'

Bulk load data in JSON format

export pwd="elastic:"

curl --user $pwd  -H 'Content-Type: application/x-ndjson' -XPOST 'https://58571402f5464923883e7be42a037917.eu-central-1.aws.cloud.es.io:9243/0/_bulk?pretty' --data-binary @<file>

Show cluster health

curl --user $pwd  -H 'Content-Type: application/json' -XGET https://58571402f5464923883e7be42a037917.eu-central-1.aws.cloud.es.io:9243/_cluster/health?pretty

Aggregation and Bucket Aggregation

For an Nginx web server, this produces web hit counts by user city:

curl -XGET --user $pwd --header 'Content-Type: application/json'  https://58571402f5464923883e7be42a037917.eu-central-1.aws.cloud.es.io:9243/logstash/_search?pretty -d '{
        "aggs": {
             "cityName": {
                    "terms": {
                     "field": "geoip.city_name.keyword",
                                "size": 50

        }
   }
  }
}
'

This expands that to product response code count of the town in an Nginx web server log

curl -XGET --user $pwd --header 'Content-Type: application/json'  https://58571402f5464923883e7be42a037917.eu-central-1.aws.cloud.es.io:9243/logstash/_search?pretty -d '{
        "aggs": {
          "city": {
                "terms": {
                        "field": "geoip.city_name.keyword"
                },
        "aggs": {
          "responses": {
                "terms": {
                     "field": "response"
                 }
           }
         }
      },
      "responses": {
                "terms": {
                     "field": "response"
                 }
        }
   }
}'

Using ElasticSearch with Basic Authentication

If you have turned on security with ElasticSearch, then you need to supply the user and password like shown below to every curl command:

curl -X GET 'http://localhost:9200/_cat/indices?v' -u elastic:(password)

Pretty Print

Add ?pretty=true to any search to pretty-print the JSON. Like this:

 curl -X GET 'http://localhost:9200/(index)/_search'?pretty=true

To query and return only certain fields

To return only certain fields, put them into the _source array:

GET filebeat-7.6.2-2020.05.05-000001/_search
 {
    "_source": ["suricata.eve.timestamp","source.geo.region_name","event.created"],
    "query":      {
        "match" : { "source.geo.country_iso_code": "GR" }
    }
}

To Query by Date

When the field is of type date, you can use date math, like this:

GET filebeat-7.6.2-2020.05.05-000001/_search
 {
    "query": {
        "range" : {
            "event.created": {
                "gte" : "now-7d/d"
            }
        }
}
}

How to Remove (Uninstall) Elasticsearch

If you no longer require Elasticsearch, you can remove the software with the following command:

sudo zypper remove elasticsearch

Example output:

Type “Y,” then press the “ENTER KEY” to proceed with the removal of Elasticsearch.

Comments and Conclusion

You have learned how to install Elasticsearch on openSUSE from Elasticsearch’s official repository and configure the basics in the tutorial. Overall, ElasticSearch has many popular features, some were mentioned at the start of the tutorial, but others include enabling users to search various fields using a single query. ElasticSearch provides an outstanding level of sharding, which means horizontal scalability, which enhances the performance even with an increase in load.

For further reading, visit the official documentation page.