Expanding monitoring
In Chapter 5, Splitting the Monolith, we discussed monitoring and collecting metrics to record what an application is doing. Measurements can tell some of the story and give a picture involving a count, a size, or time passing. To get even more information, we can use logging services to record messages our application produces.
If you have set up a Linux server, you may be familiar with the logs that pass through rsyslog and end up in a file that exists in /var/log. In a cloud service, and especially in a container, logging locally is far less useful, as we would have to then investigate all the running containers and cloud instances to discover what was happening. Instead, we can use a centralized logging service.
This could be done using tools such as AWS CloudWatch or Google's Cloud Logging, but it's also possible to run services such as Splunk or Logstash. The latter is part of a popular open source trio of tools called the ELK stack, as...