Once you have installed Elasticsearch and Kibana servers you need to grab some data. First choice could be beats modules, either Metricbeat or Packetbeat. There is also Filebeat. Altough installation instructions are available at https://www.elastic.co/guide/en/beats/metricbeat/7.17/metricbeat-installation-configuration.html I found it useful to describe it separately as this page might just disappear out of a sudden.

curl -L -O https://artifacts.elastic.co/downloads/beats/metricbeat/metricbeat-7.17.5-amd64.deb
sudo dpkg -i metricbeat-7.17.5-amd64.deb

After installation you need to change the configuration file at:

/etc/metricbeat/metricbeat.yml

Change Kibana and Elasticsearch output addresses. Then start the agent:

sudo service metricbeat start

In case this is the first time you are installing the agent against this particular Elasticsearch server you need to load visualizations and dashboard definitions:

metricbeat setup -e

Now you’re done and should be able to see you newly added host on Observability:Metrics:Inventory page. Remember to press Auto-refresh button.