Beats are lightweight data shippers. You install a Beat on your server to collect certain data and send it either to Logstash or directly to Elasticsearch. Icingabeat is a Beat that fetches data from the Icinga 2 API. It collects events generated during the monitoring process. An event can be a check result received from a plugin, a notification sent to a user, a downtime triggered through Icinga Web 2 or many other things.
Logstash Output Plugin
Logstash is a data processing pipeline. Logs and events are either actively collected or received from third party resources like Syslog or the Elastic Beats. The Icinga Output Plugin aims to build a bridge between your logging management and your monitoring. It can run various actions on your Icinga server by calling the Icinga API.
The Elasticsearch module for Icinga Web 2, embeds data that is stored in Elasticsearch in your Icinga Web 2 interface. Custom filters allow you to limit the data that should be displayed. You can give your users access to certain data types without revealing everything stored in Elasticsearch.
The ElasticsearchWriter is a feature of Icinga 2. It parses performance data collected by check plugins and forwards the data to Elasticsearch for long term storage. The main difference to icingabeat is that the ElasticsearchWriter sends all metrics and just some events. Icingabeat collects all events but does not parse performance data. The stored data can later be visualised in Kibana.