3. From the **Search Engine** list, click **Elasticsearch** or **Elasticsearch 5.0+** as the following figure shows. (The **Elasticsearch 5.0+** option is not available for Magento 2.1.)

<div markdown="1">

<h3 id="prereq-java">Install the Java Software Development Kit (JDK)</h3>

To determine if Java is already installed, enter the following command:

java -version

If the message `java: command not found` displays, you must install the Java SDK as discussed in the next section.

See one of the following sections:

* <a href="#install-prereq-java-centos">Install the latest JDK on CentOS</a>

* <a href="#install-prereq-java-ubuntu">Install the latest JDK on Ubuntu</a>

<h4 id="install-prereq-java-centos">Install the JDK on CentOS</h4>

See <a href="https://www.digitalocean.com/community/tutorials/how-to-install-java-on-centos-and-fedora#install-oracle-java-8" target="_blank">this article on digitalocean</a>.

Be sure to install the JDK and *not* the JRE.

yum -y install java-1.8.0-openjdk

<div class="bs-callout bs-callout-info" id="info">

<p>Java version 8 might not be available for all operating systems. For example, you can <a href="http://packages.ubuntu.com/" target="_blank">search the list of available packages for Ubuntu</a>.</p>

</div>

<h4 id="install-prereq-java-ubuntu">Install the JDK on Ubuntu</h4>

To install JDK 1.8 on Ubuntu, enter the following commands as a user with `root` privileges:

add-apt-repository -y ppa:webupd8team/java

apt-get -y update

apt-get install -y oracle-java8-installer

For other options, see <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/install/install_overview.html" target="_blank">Oracle documentation</a>.

{{site.data.var.ee}} version 2.2.x supports the following Elasticsearch versions:

* Elasticsearch [5.x](https://www.elastic.co/downloads/past-releases/elasticsearch-5-2-2){:target="&#95;blank"}

* Elasticsearch [2.x](https://www.elastic.co/downloads/past-releases/elasticsearch-2-4-5){:target="&#95;blank"}

Magento 2.2.3 uses [Elasticsearch PHP client](https://github.com/elastic/elasticsearch-php){:target="&#95;blank"} version 5.1. (Before version 2.2.3, Magento used PHP client version 2.0.)

* [Install Elasticsearch 5.x](#es-install-es5)

* [Install Elasticsearch 2.x](#es-install-es)

* [Upgrade from Elasticsearch 2.x to 5.x](#es-upgrade5)

{% include config/install-java8.md %}

This section discusses how to install Elasticsearch 5.2 from their repository. You can select a more recent version of 5.x, but 5.2 has been tested. {{site.data.var.ece}} supports Elasticsearch 5.2.)

1. Log in to your Magento server as a user with `root` privileges.

2. _CentOS_: Enter the following commands in the order shown:

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

vim /etc/yum.repos.d/Elasticsearch.repo

Add the following:

```

[elasticsearch-5.x]

name=Elasticsearch repository for 5.x packages

baseurl=https://artifacts.elastic.co/packages/5.x/yum

gpgcheck=1

gpgkey=https://artifacts.elastic.co/GPG-KEY-elasticsearch

enabled=1

autorefresh=1

type=rpm-md

```

Enter the following commands:

yum -y install elasticsearch

chkconfig --add elasticsearch

3. _Ubuntu_: Install the Elasticsearch 5.2 version using the [Elasticsearch documentation](https://www.elastic.co/guide/en/elasticsearch/reference/5.2/deb.html){:target="_blank"}

4. Optionally, configure Elasticsearch as needed. See [Configuring Elasticsearch](https://www.elastic.co/guide/en/elasticsearch/reference/5.2/settings.html){:target="_blank"} for more information.

5. Start Elasticsearch:

`service elasticsearch start`

6. Verify that Elasticsearch is working by entering the following command on the server on which it's running:

`curl -XGET '<host>:9200/_cat/health?v&pretty'`

A message similar to the following is displayed:

```

* Elasticsearch

{{site.data.var.ee}} version 2.2.x supports the following Elasticsearch versions:

* Elasticsearch [5.x](https://www.elastic.co/downloads/past-releases/elasticsearch-5-2-2){:target="&#95;blank"}

* Elasticsearch [2.x](https://www.elastic.co/downloads/past-releases/elasticsearch-2-4-5){:target="&#95;blank"}

* Three master databases

These <a href="{{page.baseurl}}config-guide/multi-master/multi-master.html">master databases</a> provide scalability advantages for different functional areas of the Magento application (e.g., checkout, orders, and all remaining Magento2 application tables).