Once the application is deployed to the production environment, we will need a way to constantly monitor the application's status, for example, by checking those Actuator's endpoints. When there is an outage or the system is in a critical status, for example, if the server is overloaded, we need a way to get notified.

Icinga 2 is a great fit for this purpose. It is an open source monitoring system. It uses monitoring plugins to check various services' statuses and generates performance data for reporting. Each plugin is a standalone command-line tool that performs a specific type of check. There are more than fifty standard plugins available on https://www.monitoring-plugins.org. Besides these plugins, you can also create your own check plugin. Icinga 2 also provides REST API and Web UI.

Because of the scope of this book, we will not go into the details of Icinga 2. You can find out more about it on its website, at: https://www.icinga.com/docs/icinga2/latest.

The following is the commit record of adding profile properties and turning on Actuator: