At Nabto we are using many technologies in our platform, one of them is Cassandra. We are monitoring Cassandra with the following setup setup: Cassandra + Prometheus JMX Exporter -> Prometheus -> Grafana. This setup has a component which does not meet our requirements for a production setup: The Prometheus JMX Exporter uses too much memory and CPU for the simple task it has to do.
To mitigate this problem we have created a new Java Agent which directly exports the Dropwizard metrics from the Cassandra core through the Prometheus Dropwizard Exporter and serves the metrics through a resource limited Jetty HTTP server.
The code and documentation can be found on GitHub