Which tool is known as a self-hosted open source container monitoring tool?

Prometheus is a self-hosted open-source container monitoring tool designed specifically to work with time series data. It is widely used for monitoring cloud-native applications and containers. One of its key features is its strong integration with Kubernetes environments, where it can efficiently scrape metrics from various services and provide real-time monitoring.

Prometheus operates on a pull model, sending requests to targets, which can include your containerized applications, and collecting metrics in a time-series database. It offers powerful querying capabilities and supports a wide array of visualization tools, allowing users to create insightful dashboards. Its alerting functionality also enables users to set up alerts based on specific metrics, thus facilitating proactive monitoring and response.

The other options, while notable tools in their own right, serve different purposes. For instance, Amazon Elasticsearch Service is primarily focused on search and analytics of data. Nagios XI is more aligned with server and network monitoring rather than specifically focused on container environments. Grafana, while an excellent visualization tool often used alongside Prometheus, is not a monitoring tool by itself. It depends on data sources like Prometheus for its metrics.