I want to fetch various metrics like read/write latency, disk utilisation etc. of each of my Cassandra nodes(without using JMX) as a JSON object. It seems to me that MetricsServlet, can do exactly that. However, I'm still not able to figure out, what all do I need to do in order to use it(metrics-servlets does not come with Cassandra). I'll appreciate if I can get some advice/sample code(for fetching any metric).
Cassandra is not a java web server, it doesnt support servlets. You would need to start a java web server in same JVM as Cassandra and load those servlets. While possible its probably a lot less work to just query the metrics via JMX and convert to JSON with an external application or to expose JMX via http with something like MX4J (what I would recommend)