Barnes

Ruby runtime metrics for Heroku Runtime Metrics. Collects GC stats, ObjectSpace counts, and Puma thread/pool metrics and POSTs them directly to HEROKU_METRICS_URL.

Originally a fork of trashed.

Setup

Rails

Add this to your Gemfile:

gem "barnes"

Then run:

$ bundle install

Barnes will start automatically via a Railtie when HEROKU_METRICS_URL is set in the environment (this is provided automatically on Heroku dynos).

Non-Rails (Puma)

Add the gem to your Gemfile:

gem "barnes"

Then in your puma.rb:

require 'barnes'

before_fork do
  Barnes.start
end

How it works

Barnes starts a background thread that collects metrics at a configurable interval (default: 10 seconds) and POSTs them as JSON to the URL in HEROKU_METRICS_URL.

Barnes is a silent no-op when:

• HEROKU_METRICS_URL is not set (e.g. local development)
• The dyno is a one-off run.* dyno

No external dependencies or sidecar processes are required.

Configuration

Barnes.start(
  interval: 10,   # seconds between reports (default: 10)
  panels:   []    # custom instrumentation panels (default: built-in ResourceUsage)
)

Requirements

• Ruby >= 3.1