I have a server provided by SSD nodes which I use for my business website along with a few small node.js applications. At the moment due to the size of these projects I have the web, app and database layers all hosted on the same single server. Whilst I have automated most tasks for managing this server I currently have no single simple view of its resource allocation nor any monitoring/ alerting in place if things go downhill.

I'm on the lookout for any free/open source monitoring and alerting applications. I've used Webmin in the past I'm not 100% confident it covers this area fully.

Any options put forward are appreciated!