Add GoodJob metrics integration and update Prometheus configuration

- Introduced a new `GoodJobMetricsWithQueues` class for tracking GoodJob queue counts using Prometheus.
- Updated `application.rb` to include Prometheus exporter dependencies and configuration.
- Added a new `prometheus_exporter.yml` file to manage Prometheus settings across environments.
- Modified `puma.rb` to remove redundant Prometheus instrumentation code.
- Enabled eager loading in the development environment for better performance.
- Updated GoodJob initializer to start the new metrics tracking.

These changes enhance monitoring capabilities for job processing and improve application performance.

app/lib/scraper/metrics/good_job_metrics_with_queues.rb

@@ -0,0 +1,47 @@
+# typed: strict
+class Scraper::Metrics::GoodJobMetricsWithQueues < PrometheusExporter::Instrumentation::PeriodicStats
+  extend T::Sig
+
+  sig do
+    params(
+      client: T.nilable(PrometheusExporter::Client),
+      frequency: Numeric,
+    ).void
+  end
+  def self.start(client: nil, frequency: 5)
+    client ||= PrometheusExporter::Client.default
+
+    gauge =
+      T.cast(
+        client.register(
+          :gauge,
+          "good_job_queue_counts",
+          "GoodJob queue counts",
+        ),
+        PrometheusExporter::Client::RemoteMetric,
+      )
+
+    worker_loop do
+      SCOPES.each do |scope|
+        GoodJob::Job
+          .send(scope)
+          .group(:queue_name, :job_class)
+          .count
+          .each do |(queue_name, job_class), count|
+            gauge.observe(
+              count,
+              { queue_name: queue_name, job_class: job_class },
+            )
+          end
+      end
+    end
+
+    super
+  end
+
+  SCOPES = %i[all scheduled retried queued running finished succeeded discarded]
+
+  sig { params(client: PrometheusExporter::Client).void }
+  def collect(client)
+  end
+end

app/models/redux_application_record.rb

@@ -25,8 +25,7 @@ class ReduxApplicationRecord < ActiveRecord::Base
 
   sig { params(action: Symbol).void }
   def observe(action)
-    ACTIVE_RECORD_COUNTER.observe(
-      1,
+    ACTIVE_RECORD_COUNTER.increment(
       { method: action, class_name: self.class.name },
     )
   end

config/application.rb

@@ -3,6 +3,13 @@ require_relative "boot"
 require "rails/all"
 require "sorbet-runtime"
 
+require "prometheus_exporter"
+require "prometheus_exporter/client"
+require "prometheus_exporter/metric"
+require "prometheus_exporter/metric/counter"
+require "prometheus_exporter/instrumentation"
+require "prometheus_exporter/middleware"
+
 module ReduxScraper
   class Application < Rails::Application
     config.active_support.deprecation = :raise
@@ -32,5 +39,7 @@ module ReduxScraper
     # in config/environments, which are processed later.
     #
     config.time_zone = "Pacific Time (US & Canada)"
+    config.x.prometheus_exporter =
+      Rails.application.config_for("prometheus_exporter")
   end
 end

config/environments/development.rb

@@ -11,7 +11,7 @@ Rails.application.configure do
   config.cache_classes = false
 
   # Do not eager load code on boot.
-  config.eager_load = false
+  config.eager_load = true
 
   # Show full error reports.
   config.consider_all_requests_local = true

config/initializers/good_job.rb

@@ -32,6 +32,8 @@ ActiveSupport.on_load(:good_job_application_controller) do
     policy.style_src :self, :https, "cdnjs.cloudflare.com"
     policy.style_src_elem :self, :https, "cdnjs.cloudflare.com"
   end
+
+  Scraper::Metrics::GoodJobMetricsWithQueues.start
 end
 
 ActiveSupport.on_load(:good_job_base_record) do
@@ -44,8 +46,3 @@ ActiveSupport.on_load(:good_job_base_record) do
     after_create { Scraper::JobBase.last_good_job_execution = self }
   end
 end
-
-require "prometheus_exporter/instrumentation"
-ActiveSupport.on_load(:good_job_application_controller) do
-  PrometheusExporter::Instrumentation::GoodJob.start
-end

config/initializers/prometheus_exporter.rb

@@ -1,12 +1,12 @@
-# typed: true
-require "prometheus_exporter"
-require "prometheus_exporter/client"
-require "prometheus_exporter/metric"
-require "prometheus_exporter/metric/counter"
-
-unless Rails.env.test?
-  require "prometheus_exporter/middleware"
+# typed: strict
 
+if Rails.configuration.x.prometheus_exporter[:enabled]
   # This reports stats per request like HTTP status and timings
   Rails.application.middleware.unshift PrometheusExporter::Middleware
+  PrometheusExporter::Instrumentation::ActiveRecord.start(
+    custom_labels: {
+      type: "puma_single_mode",
+    }, #optional params
+    config_labels: %i[database host], #optional params
+  )
 end

config/prometheus_exporter.yml

@@ -0,0 +1,14 @@
+test:
+  enabled: true
+
+development:
+  enabled: true
+
+staging:
+  enabled: true
+
+production:
+  enabled: true
+
+worker:
+  enabled: true

config/puma.rb

@@ -42,9 +42,3 @@ pidfile ENV.fetch("PIDFILE") { "tmp/pids/server.pid" }
 
 # Allow puma to be restarted by `bin/rails restart` command.
 plugin :tmp_restart
-
-require 'prometheus_exporter/instrumentation'
-PrometheusExporter::Instrumentation::ActiveRecord.start(
-  custom_labels: { type: "puma_single_mode" }, #optional params
-  config_labels: [:database, :host] #optional params
-)