chore(yabeda): use webrick and check enabled flag

README.md

@@ -192,3 +192,5 @@ La compatibilité est testée par Browserstack.<br>[<img src="app/assets/images/
 [![View performance data on Skylight](https://badges.skylight.io/status/zAvWTaqO0mu1.svg)](https://oss.skylight.io/app/applications/zAvWTaqO0mu1)
 
 Nous utilisons Skylight pour suivre les performances de notre application.
+
+Par ailleurs, nous utilisons [Yabeda](https://github.com/yabeda-rb/yabeda) pour exporter des metriques au format prometheus. L'activation se fait via la variable d'environnement `PROMETHEUS_EXPORTER_ENABLED` voir config/env.example.optional .

config.ru

@@ -2,5 +2,9 @@
 
 require_relative "config/environment"
 
+if ENV['PROMETHEUS_EXPORTER_ENABLED'] == 'enabled'
+  Yabeda::Prometheus::Exporter.start_metrics_server!
+end
+
 run Rails.application
 Rails.application.load_server

config/env.example.optional

@@ -244,7 +244,7 @@ REDIS_SIDEKIQ_PASSWORD='sentinel_and_redis_password'
 REDIS_SIDEKIQ_USERNAME='sentinel_and_redis_username'
 
 # configuration for prometheus metrics web server
-# launched with sidekiq
+# launched with sidekiq and puma
 PROMETHEUS_EXPORTER_BIND="0.0.0.0"
 PROMETHEUS_EXPORTER_PORT="9394"
 PROMETHEUS_EXPORTER_ENABLED="disabled"

config/initializers/prometheus_metrics.rb

@@ -0,0 +1,3 @@
+if ENV['PROMETHEUS_EXPORTER_ENABLED'] == 'enabled' && !Sidekiq.server?
+  Prometheus::Client.config.data_store = Prometheus::Client::DataStores::DirectFileStore.new(dir: Rails.root.join('tmp', 'prometheus'))
+end