Expose prometheus metrics at /metrics

.app_version

@@ -1 +1 @@
-0.30.3
+0.30.4

.gitignore

@@ -65,6 +65,7 @@
 .dotnet/
 .cursorrules
 .cursormemory.md
+.serena/project.yml
 
 /config/credentials/production.key
 /config/credentials/production.yml.enc

CHANGELOG.md

@@ -4,6 +4,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+# [0.30.4] - 2025-07-25
+
+## Added
+
+- Prometheus metrics are now available at `/metrics`. Configure `METRICS_USERNAME` and `METRICS_PASSWORD` environment variables for basic authentication. All other prometheus-related environment variables are also necessary.
+
+
+
 # [0.30.3] - 2025-07-23
 
 ## Changed

app/controllers/metrics_controller.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class MetricsController < ApplicationController
+  http_basic_authenticate_with name: ENV['METRICS_USERNAME'], password: ENV['METRICS_PASSWORD'], only: :index
+
+  def index
+    result = PrometheusMetrics.fetch_data
+
+    if result[:success]
+      render plain: result[:data], content_type: 'text/plain'
+    elsif result[:error] == 'Prometheus exporter not enabled'
+      head :not_found
+    else
+      head :service_unavailable
+    end
+  end
+end

app/services/prometheus_metrics.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require 'net/http'
+require 'uri'
+
+class PrometheusMetrics
+  class << self
+    def fetch_data
+      return { success: false, error: 'Prometheus exporter not enabled' } unless prometheus_enabled?
+
+      host = ENV.fetch('PROMETHEUS_EXPORTER_HOST', 'localhost')
+      port = ENV.fetch('PROMETHEUS_EXPORTER_PORT', 9394)
+
+      begin
+        response = Net::HTTP.get_response(URI("http://#{host}:#{port}/metrics"))
+
+        if response.code == '200'
+          { success: true, data: response.body }
+        else
+          { success: false, error: "Prometheus server returned #{response.code}" }
+        end
+      rescue => e
+        Rails.logger.error "Failed to fetch Prometheus metrics: #{e.message}"
+        { success: false, error: e.message }
+      end
+    end
+
+    private
+
+    def prometheus_enabled?
+      DawarichSettings.prometheus_exporter_enabled?
+    end
+  end
+end

config/routes.rb

@@ -87,6 +87,8 @@ Rails.application.routes.draw do
     devise_for :users
   end
 
+  resources :metrics, only: [:index]
+
   get 'map', to: 'map#index'
 
   namespace :api do