ELK is a combination of three open source tools: Elasticsearch, Logstash, and Kibana:

• Logstash is an open source tool for collecting, parsing, and storing logs for future use.
• Elasticsearch is a search and analytics engine. It works on logs collected by Logstash.
• Kibana is a web interface that can be used to view data in a useful and appealing format.

The following diagram shows how the three tools work together:

As the preceding architecture explains, the three tools of ELK work together to fetch and showcase the analytics information to the end user. Logstash is responsible for fetching logs from a distributed system, where different Microservices might be deployed on different machines.

Once the logs are available, Elasticsearch helps to implement search and analysis capabilities. Finally, Kibana displays the data in various graphs or diagrams, which are more meaningful to the user and gives easily actionable items.