My main use case for Nagios Core on CentOS is to monitor remote servers and configure alerting. I use default plugins available in NRPE to monitor Linux instances and other running services. I created custom plugins to monitor Docker containers and the processes running inside them, all monitored through Nagios.
The way I set up Nagios Core on CentOS is unique because I monitor Docker containers at a granular level. If any processes, such as Python microservices, exit, I receive alerting to Google Chat and email. A separate team works with me to continuously monitor for alerts and inform respective team members to quickly investigate and resolve problems.