Prometheus metrics collectors for shigoto.

Declares Prometheus metrics for the shigoto telemetry surface (see the Telemetry contract) and attaches telemetry handlers that translate events into counter / histogram updates.

This package has no web dependency and stands up no listener of its own. Serve the scrape output from your application's existing web layer. For a Nova app (the shigoto ecosystem's web framework), a one-line controller does it:

-module(metrics_controller).
-export([index/1]).

index(_Req) ->
    {status, 200, #{~"content-type" => ~"text/plain; version=0.0.4"},
        shigoto_metrics:scrape()}.

then route {"/metrics", fun metrics_controller:index/1, #{methods => [get]}}.

If you are not on Nova, mount prometheus_cowboy2_handler on your own Cowboy listener, or return scrape/0 from whatever handler you already run. Enabling metrics is just:

{ok, _} = application:ensure_all_started(shigoto_metrics).

auto_setup (default true) declares the metrics and attaches the handlers at boot; set it to false to call setup/0 yourself.