Elasticsearch 7.2.1 Linux Installation

System Requirements

Linux operating system with apt package manager
network connection with static ip address and (temporary) internet access
user-account with sudo rights

Installation Procedure

Files needed during the installation (plugins.zip, relevant files from the conf-directory, openjdk 1.8) can be found here: https://files.optimal-systems.org/index.php/s/Pd66oYD8TcZm6CM
(Tested with Ubuntu 20.10: https://releases.ubuntu.com/20.10/ubuntu-20.10-live-server-amd64.iso)

Download the needed files from the above link to the linux system and unzip.

wget https://files.optimal-systems.org/index.php/s/Pd66oYD8TcZm6CM/download -Ofiles.zip
sudo apt install unzip
unzip files.zip

Add elasticsearch repository and install elasticsearch,

sudo apt install apt-transport-https
wget -qO esrepo https://artifacts.elastic.co/GPG-KEY-elasticsearch
sudo apt-key add esrepo
sudo add-apt-repository "deb https://artifacts.elastic.co/packages/7.x/apt stable main"
sudo apt update
sudo apt install elasticsearch=7.2.1

Enable elasticsearch service

sudo systemctl daemon-reload
sudo systemctl enable elasticsearch.service

Allow elasticsearch to lock all memory

sudo mkdir -p /etc/systemd/system/elasticsearch.service.d/
sudo nano /etc/systemd/system/elasticsearch.service.d/override.conf

--> Enter the following lines:
[Service]
LimitMEMLOCK=infinity

--> Save file (using STRG+X then Y)

sudo systemctl daemon-reload

Replace the installed JDK 11 with OpenJDK 8 in the elasticsearch folder

sudo rm -rf /usr/share/elasticsearch/jdk
cd Elasticsearch\ 7.2.1
unzip jdk-8u262-ojdkbuild-linux-x64.zip
sudo mv jdk-8u262-ojdkbuild-linux-x64 jdk
sudo mv jdk /usr/share/elasticsearch/

Unzip and copy the Intrafind plugins to the elasticsearch plugins folder

unzip plugins.zip 
sudo cp -r plugins/* /usr/share/elasticsearch/plugins/
sudo chmod -R 755 /usr/share/elasticsearch
sudo chown -R elasticsearch:elasticsearch /usr/share/elasticsearch

Copy elasticsearch configuration
```
sudo cp conf/* /etc/elasticsearch/
```
(optional) Change default java heap settings from 8 GB to desired value
```
sudo nano /etc/elasticsearch/jvm.options
```
- change values of lines -Xms and -Xmx to your desired value (values must be the same!).
Configure settings in elastisearch.yml
```
sudo nano /etc/elasticsearch/elasticsearch.yml
```
- Check and/or change the following settings:
  - path.data: data directory
  - path.logs: log directory
  - cluster-name
  - node.name: must be unique over all nodes (if multiple exist)
  - cluster.initial_master_nodes: list of nodes for master quorum
  - discovery.seed_hosts: list of nodes to check for existing cluster

Create data and logs directories

sudo mkdir -p /opt/elasticsearch7/data
sudo mkdir /opt/elasticsearch7/logs
sudo chown -R elasticsearch:elasticsearch /opt/elasticsearch7

Replace the directory names with the paths configured in the previous step

Start elasticsearch and check for errors

sudo systemctl start elasticsearch.service

#wait some seconds
sudo systemctl status elasticsearch.service

#once the "Active" status is "active (running)"
sudo tail -f /opt/elasticsearch7/logs/es-red.log

#once you see "license [<guid>] mode [basic] - valid" you can continue to the next step (use STRG+C to exit tail -f)

If this is the only / first elasticsearch node, setup the built-in users passwords

cd /usr/share/elasticsearch/bin
sudo ./elasticsearch-setup-passwords auto -b > ~/built-in.usr
less ~/built-in.usr

Note the password of the elastic user. It is needed for the service-manager setup.
(For security reasons the built-in.usr file should be deleted after elasticsearch and the service-manager are installed and working ok.)