Prometheus vs. Sensu vs. Graphite

Prometheus is a systems and service monitoring system. It collects metrics from configured targets at given intervals, evaluates rule expressions, displays the results, and can trigger alerts if some condition is observed to be true.

A monitoring framework that aims to be simple, malleable, and scalable. Essentially, Sensu takes the results of “check” scripts run across many systems, and if certain conditions are met; passes their information to one or more “handlers”. Checks are used, for example, to determine if a service like Apache is up or down.

Graphite does two things: 1) Store numeric time-series data and 2) Render graphs of this data on demand