So what's Prometheus? Its developers describe it as follows:
Prometheus is an open-source system's monitoring and alerting toolkit built at SoundCloud. Since its inception in 2012, it has become the standard for instrumenting new services at SoundCloud and is seeing growing external usage and contributions.
OK, but what does that have to do with cAdvisor? Well, Prometheus has quite a powerful database backend that stores the data it imports as a time series of events.
Wikipedia describes a time series as follows:
"A time series is a sequence of data points, typically consisting of successive measurements made over a time interval. Examples of time series are ocean tides, counts of sunspots, and the daily closing value of the Dow Jones Industrial ...