We touched only the surface of what the ELK stack can do. ElasticSearch is a very powerful database that can be scaled easily and store vast amounts of data. LogStash provides almost unlimited possibilities that allow us to use virtually any data source as input (in our case syslog), transform it into any form we find useful, and output to many different destinations (in our case ElasticSearch). When a need occurs, you can use Kibana to go through the logs generated by your system. Finally, the tool that made all that happen is LogSpout. It ensured that all the logs produced by any of the containers running inside our cluster are collected and shipped to LogStash.
This goal of the chapter was to explore a potential solution to deal with massive quantities of logs and give you a base understanding how to collect them from services running inside a Swarm cluster. Do you know everything you should know about logging? You probably don't. However, I hope you have a good base to explore...