> Config file isn't a config file, it's an executed bit of Clojure code

For stream processing engines, configuration will be code. Unfortunate, but unavoidable.

> Riemann is not a replacement for an alerting mechanism

> Riemann is not a replacement for a trend graphing mechanism.

Indeed it is not. It's misadvertised as a monitoring solution, while it's a stream processing engine.

What I think of it is that you're supposed build a monitoring system on top of stream processing engine. It's a pity Riemann doesn't allow to subscribe to its streams from the outside, so to add any message destination you need to update its config.