enable yabeda sidekiq metrics

a webserver is launched with the sidekiq process. It listen on the 9394 port and bind on 0.0.0.0 by default.

config/env.example.optional

@@ -246,6 +246,12 @@ REDIS_SIDEKIQ_MASTER='master_name'
 REDIS_SIDEKIQ_PASSWORD='sentinel_and_redis_password'
 REDIS_SIDEKIQ_USERNAME='sentinel_and_redis_username'
 
+# configuration for prometheus metrics web server
+# launched with sidekiq
+PROMETHEUS_EXPORTER_BIND="0.0.0.0"
+PROMETHEUS_EXPORTER_PORT="9394"
+PROMETHEUS_EXPORTER_ENABLED="disabled"
+
 # Setup log level, info if nil
 # can be debug, info, warn, error, fatal, and unknown
 DS_LOG_LEVEL='info'

config/initializers/sidekiq.rb

@@ -16,6 +16,11 @@ if ENV.has_key?('REDIS_SIDEKIQ_SENTINELS')
       role: :master
     }
 
+    if ENV['PROMETHEUS_EXPORTER_ENABLED'] == 'enabled'
+      Yabeda.configure!
+      Yabeda::Prometheus::Exporter.start_metrics_server!
+    end
+
     if ENV['SKIP_RELIABLE_FETCH'].blank?
       Sidekiq::ReliableFetch.setup_reliable_fetch!(config)
     end