Monitoring is a question to be considered carefully -- rarely is a solution one-size-fits-all. Icinga2 is a great option for basic monitoring.

Icinga2 fills a niche very similar to that of the Nagios project. Where Icinga excels (over Nagios) is in the niceties of its configuration language, as well as many advanced features. As an open source project, Icinga offers a free, open, and complete solution for most operation monitoring. In particular, Icinga is great for monitoring hosts and alerting on basic metrics.

There are a few disadvantages of Icinga -- the frontend is php, the stack is fairly monolithic, and the architecture does not take advantage of time-series databases. Having used (and set up) both monolithic monitoring infrastructure and pipelined infrastructure, I have found that although the monolithic (nagios/icinga2) systems have a much lower barrier to entry, a pipelined architecture tends to be more maintainable for more advanced requirements.

Easy to use, to install. HA capability and satellite usage are greats features Windows Installation

Reporting features are not great. If we need to create some reports of Availability module are not reporting somes informations or graph Grafana / graph integration is not easy Documentation is not complete Windows Integration and check are not easy to use. It will be great to install with the agent the powershell checks

We chose to build our own knowledge about Icinga systems, so we don't rely on any support or vendor. It has it's challenges that open source projects like that bring with them, but community is large and solutions are generally easy to find.

It is free and very flexible. Community is large and develops many extensions to the core project.

It has constant development that can be a problem with outside plugins that are not supported so professionally. Also core product needs some knowledge to set up and maintain. It is not just an install wizard.

Easy to deploy, in a cloud-native fashion using Icinga satellites, provides the core functionality nicely that anyone in their right mind is expecting from a monitoring system, but might lack some things that larger enterprises consider "mandatory".

Icinga is, even though it's already at this point in time a relatively mature open source project, getting updates released very frequently. It seems to be increasing the feature upside it has over its most direct competition, slowly, but surely. The API is also more straightforward in design over its direct competition.

Graphs and visualization over longer time periods is really lacking or if existing, really difficult to use. The .conf file configuration also feels very old school now in 2021.

Icinga works great in real-time monitoring and can be easily integrated with other tools (Slack, emails, etc.) for notifications.

Icinga allows you to monitor all your hosts and services/applications in one place, allowing for extensive and deep customization by means of templates and ad-hoc scripts.

It is quite complicated, at least at the beginning, to understand how the Icinga system works. You need to understand how services, groups, templates, commands, rules work before implementing your checks.