Leela is a system that allows you to store, retrieve and monitor the performance metrics of your systems in real-time using a variety of protocols.
For data collection, currently you can use collectd or a fairly simple text protocol over UDP. This gives you a decent coverage of standard systems and applications at the same making it very easy to collect custom metrics.
Data retrieval can be done using a restful API which makes it easier to create dashboards, analyze historical data or simply plot graphs in the browser.
You can even monitor real-time data using XMPP protocol. Simply register a query and you will start receiving events in JSON as soon as they are received by the server.
Monitoring and tuning