How to install Elasticsearch on Ubuntu

Elasticsearch is a product by Elasticsearch BV. It is available on Github and the company also hosts Elasticsearch's apt repository for Ubuntu.

It is developed using Java thus you'll also need to install Java Runtime Environment alongside the Elasticsearch binary.

1. Add Elasticsearch repository to apt.
   1. Add GPG key of Elasticsearch's repository via apt-key.

      $ wget --quiet --output-document=- https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -
      [sudo] password for user:
      OK

   2. Add Elasticsearch's repository to apt's repository list.

      $ echo "deb https://artifacts.elastic.co/packages/6.x/apt stable main" | sudo tee -a /etc/apt/sources.list.d/elastic-6.x.list
      deb https://artifacts.elastic.co/packages/6.x/apt stable main

2. Update list of available packages from the newly added repository.

   $ sudo apt update

3. Install latest Java Runtime Environment.

   $ sudo apt install --assume-yes default-jre

4. Install Elasticsearch package.

   $ sudo apt install --assume-yes elasticsearch

5. Enable access to port 9200 and 9300 from the local firewall.

   $ sudo ufw allow 9200
   Rules updated
   Rules updated (v6)
   $ sudo ufw allow 9300
   Rules updated
   Rules updated (v6)

6. Configure Elasticsearch options located in /etc/elasticsearch/elasticsearch.yml.
   1. Allow connection from remote host.

      network.host: 0.0.0.0

7. Configure Elasticsearch to automatically start during boot.

   $ sudo systemctl enable elasticsearch
   Synchronizing state of elasticsearch.service with SysV service script with /lib/systemd/systemd-sysv-install.
   Executing: /lib/systemd/systemd-sysv-install enable elasticsearch
   Created symlink /etc/systemd/system/multi-user.target.wants/elasticsearch.service → /usr/lib/systemd/system/elasticsearch.service.

8. Start Elasticsearch service.

    $ sudo systemctl start elasticsearch

9. Test if installation was successfully by querying Elasticsearch service.

   $ curl 127.0.0.1:9200
   {
     "name" : "90mQ0vJ",
     "cluster_name" : "elasticsearch",
     "cluster_uuid" : "4oFjuDQLRtiCrkjrIKyZuQ",
     "version" : {
       "number" : "6.4.0",
       "build_flavor" : "default",
       "build_type" : "deb",
       "build_hash" : "595516e",
       "build_date" : "2018-08-17T23:18:47.308994Z",
       "build_snapshot" : false,
       "lucene_version" : "7.4.0",
       "minimum_wire_compatibility_version" : "5.6.0",
       "minimum_index_compatibility_version" : "5.0.0"
     },
     "tagline" : "You Know, for Search"
   }

   You will get the following error if you immediately test the service after starting it up because Elasticsearch takes a while to start.

   curl 127.0.0.1:9200
   curl: (7) Failed to connect to 127.0.0.1 port 9200: Connection refused