Shinken is a monitoring framework written in Python, designed to scale to large environments. It is Nagios-compatible: existing Nagios configurations and plugins work without changes. Its architecture is distributed, with an arbiter, schedulers, pollers, reactionners and brokers that can be spread across so-called realms, and it integrates with tools such as Thruk, Centreon, Graphite and PNP4Nagios. Shinken runs on any operating system that supports Python, including Linux, Windows and FreeBSD. You install and operate it yourself.
The source code is published on GitHub under the AGPL-3.0 licence. Because there is no vendor-hosted service, all monitoring data stays on the infrastructure where you run Shinken, and you decide its location and jurisdiction. No commercial cloud with a foreign parent company is involved. The documentation and repository do not show a clear release status, so check how actively the project is maintained before adopting it, and whether you would need in-house capacity to look after it.