Module: RailsPodKit::Puma

Defined in:
lib/rails_pod_kit/puma.rb

Overview

Puma integration. Encapsulates the Puma plugins the yabeda stack needs so that config/puma.rb stays a one-liner:

require 'rails_pod_kit/puma'
RailsPodKit::Puma.activate(self)
  • control app yabeda-puma-plugin reads the Puma thread-pool stats through Puma's control app, so we activate one (localhost-only, no token) if the app hasn't.
  • plugin :yabeda (yabeda-puma-plugin) registers a Yabeda collector for Puma thread-pool / worker stats.
  • plugin :yabeda_prometheus (yabeda-puma-plugin) starts the in-process HTTP server that serves /metrics, fork-safe under preload_app! + clustered workers.

No-op when disabled or in the test env so the suite never binds the port.

Class Method Summary collapse

Class Method Details

.activate(puma_config) ⇒ Object 



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# File 'lib/rails_pod_kit/puma.rb', line 25

def activate(puma_config)
  return unless RailsPodKit.enabled?

  ENV['PROMETHEUS_EXPORTER_PORT'] ||= RailsPodKit.config.port.to_s

  # The Puma plugin only pulls in the exporter class; we must also load the
  # full mmap module so `Yabeda::Prometheus::Mmap.registry` exists and the
  # mmap adapter is registered. The gem's main entry (lib/rails_pod_kit.rb)
  # already loaded it at Bundler.require, so this is normally a no-op — it
  # matters only under `puma -C config/puma.rb`, where config/puma.rb runs
  # before Rails and thus before the main entry, so this is the first require.
  require 'yabeda/prometheus/mmap'

  # The control app exposes Puma's /stats over a localhost-only socket that
  # the yabeda collector queries. `no_token: true` is safe because the
  # socket is never exposed outside the pod.
  puma_config.activate_control_app(RailsPodKit.config.puma_control_url, no_token: true)

  puma_config.plugin :yabeda
  puma_config.plugin :yabeda_prometheus

  # Silence the exporter's per-scrape access log. The `prometheus_silence_logger`
  # DSL method is defined by the :yabeda_prometheus plugin, so this must run
  # after the plugin is loaded above. See Config#silence_exporter_access_log.
  puma_config.prometheus_silence_logger(true) if RailsPodKit.config.silence_exporter_access_log

  # `config/puma.rb` is evaluated before Rails is loaded, so requiring this
  # gem here loads yabeda *before* `defined?(Rails)`, and yabeda's Railtie
  # (which would call `Yabeda.configure!` at after_initialize) never
  # registers. So we drive configuration ourselves from the exporter-boot
  # hook, which runs after Rails has booted and after the Puma plugin has
  # registered its collector.
  puma_config.on_prometheus_exporter_boot do
    # Under the :web policy the always-on web process is the single source of
    # Sidekiq global (Redis-wide) queue metrics, so workers don't duplicate
    # them. Done here (not in activate) because requiring yabeda-sidekiq —
    # which pulls in Sidekiq — before Rails boots corrupts Sidekiq's
    # ActiveJob adapter load order. By exporter-boot, Rails has loaded
    # Sidekiq properly and the web's Sidekiq client (Redis) is configured.
    if RailsPodKit.config.sidekiq_global_metrics == :web
      require 'rails_pod_kit/sidekiq'
      RailsPodKit::Sidekiq.enable_global_collection!
    end

    require 'yabeda'
    Yabeda.configure! unless Yabeda.already_configured?
  end
end