A monitoring tool, not a monitoring project.
Icinga is a serious, battle-tested system. With deep roots in the Nagios ecosystem, it gives you full control over every check, every template, and every notification rule. If you have the engineering time to own every piece of the stack, it is a reasonable choice.
But it grew from a Nagios fork, and the architecture shows it. Configuration lives in a DSL or the Director module. Checks need defining, templates need tuning, and getting from a fresh install to something genuinely useful takes real work. The check-based model itself predates modern observability.
The monitoring tool becomes its own project. Icinga is open-source and free to run, but running it is the operative word. You provision and maintain the daemon, the IDO database, and the web server, plus the updates and backups that come with them. Free in license, expensive in time and infrastructure.
Simple Observability takes the opposite bet. Server health, centralized logs, cron jobs, and other essential checks flow into a single dashboard right out of the box. Predefined defaults handle the decisions you would otherwise spend an afternoon configuring. No database to tune, no daemon to keep alive, no DSL to learn. You install the agent, and the picture is there.
