Lager backend which will count the events happening in folsom. Can be used to get metric overviews of the amount of logging happening in a subsystem so one can correlate data between subsystems. It is also effective at figuring out if certain subsystems are the source of errors in a large code base.
The code is written for Issuu and is in use inside a couple of production systems. It is used to track error rates for the subsystems, so we can target the areas which are the most problematic. We could obtain the same information by going through log files manually, but the counts provide a way nicer overview of where the problems originate from.
The module lager_folsom_backend is a new lager handler backend. It requires Lager 2.0 and there will probably not be too much backporting done for 1.0. You use the system by injecting a handler:
{lager_folsom_backend, [debug]}, ⋯
in your handler configuration. This will let lager log any event at the debug level into folsom. You can then use tools to export folsom counters and obtain nice graphs of what is going on inside the system.