We've been using riemann and it's wonderful. There's a little bit of learning curve as the configurations are just clojure code, but since it's all code you can

We've been using riemann and it's wonderful. There's a little bit of learning curve as the configurations are just clojure code, but since it's all code you can build whatever you want on top of it if you know some Clojure. The DSL is well thought of and we ended up writing a REST API on top of riemann to make our monitoring stack self-serviced for all the internal users.