Module: Pgbus::Metrics

Defined in:
lib/pgbus/metrics.rb,
lib/pgbus/metrics/backend.rb,
lib/pgbus/metrics/subscriber.rb,
lib/pgbus/metrics/backends/statsd.rb,
lib/pgbus/metrics/backends/prometheus.rb,
lib/pgbus/metrics/prometheus_exporter.rb

Overview

Backend-agnostic metrics adapter.

Pgbus emits a family of pgbus.* ActiveSupport::Notifications events; Pgbus::Instrumentation is the single source of truth for the catalog. The AppSignal integration is one consumer of those events; this namespace is a second, vendor-neutral consumer that forwards the same event→metric mapping to a configurable backend so teams on Prometheus, Datadog, or plain StatsD get metrics without hand-writing subscribers.

Opt in via config.metrics_backend = :prometheus | :statsd | <Backend>. The default is nil, which installs no subscription (zero overhead). Installation happens from the engine, mirroring the AppSignal initializer.

Defined Under Namespace

Modules: Backends, Subscriber Classes: Backend, PrometheusExporter

Class Method Summary collapse

Class Method Details

.resolve_backend(value) ⇒ Object

Coerce a configuration value into a concrete Backend instance.

nil          -> Backend::Null (no-op)
:prometheus  -> Backends::Prometheus
:statsd      -> Backends::Statsd (host/port from configuration)
Backend inst -> returned unchanged


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# File 'lib/pgbus/metrics.rb', line 25

def resolve_backend(value)
  case value
  when nil
    Backend::Null.new
  when :prometheus
    Backends::Prometheus.new
  when :statsd
    config = Pgbus.configuration
    Backends::Statsd.new(host: config.statsd_host, port: config.statsd_port)
  when Backend
    value
  else
    raise ArgumentError,
          "metrics_backend must be nil, :prometheus, :statsd, or a " \
          "Pgbus::Metrics::Backend instance (got #{value.inspect})"
  end
end