Use only ENV for metrics folder location

app/controllers/metrics_controller.rb

@@ -11,9 +11,9 @@ class MetricsController < ActionController::Base
   ].freeze
   def metrics
-    render_404 unless Gitlab::Metrics.prometheus_metrics_enabled?
-    metrics_text = Prometheus::Client::Formats::Text.marshal_multiprocess(Settings.gitlab['prometheus_multiproc_dir'])
+    return render_404 unless Gitlab::Metrics.prometheus_metrics_enabled?
+    metrics_text = Prometheus::Client::Formats::Text.marshal_multiprocess(multiprocess_metrics_path)
     response = health_metrics_text + "\n" + metrics_text
     render text: response, content_type: 'text/plain; version=0.0.4'
@@ -21,6 +21,10 @@ class MetricsController < ActionController::Base
   private
+  def multiprocess_metrics_path
+    Rails.root.join(ENV['prometheus_multiproc_dir'])
+  end
+
   def health_metrics_text
     results = CHECKS.flat_map(&:metrics)

config.ru

@@ -13,10 +13,9 @@ if defined?(Unicorn)
     # Max memory size (RSS) per worker
     use Unicorn::WorkerKiller::Oom, min, max
   end
-
-  # TODO(lyda): Needs to be set externally.
-  ENV['prometheus_multiproc_dir'] = '/tmp/somestuff'
 end
+# set default for multiproces metrics gathering
+ENV['prometheus_multiproc_dir'] ||= 'tmp/prometheus_data_dir'
 require ::File.expand_path('../config/environment',  __FILE__)

config/gitlab.yml.example

@@ -102,11 +102,6 @@ production: &base
     # The default is 'shared/cache/archive/' relative to the root of the Rails app.
     # repository_downloads_path: shared/cache/archive/
-    ## Prometheus Client Data directory
-    # To be used efficiently in multiprocess Ruby setup like Unicorn, Prometheus client needs to share metrics with other instances.
-    # The default is 'tmp/prometheus_data_dir' relative to Rails.root
-    # prometheus_multiproc_dir: tmp/prometheus_data_dir
-
   ## Reply by email
   # Allow users to comment on issues and merge requests by replying to notification emails.
   # For documentation on how to set this up, see http://doc.gitlab.com/ce/administration/reply_by_email.html

config/initializers/1_settings.rb

@@ -242,7 +242,6 @@ Settings.gitlab['import_sources'] ||= %w[github bitbucket gitlab google_code fog
 Settings.gitlab['trusted_proxies'] ||= []
 Settings.gitlab['no_todos_messages'] ||= YAML.load_file(Rails.root.join('config', 'no_todos_messages.yml'))
 Settings.gitlab['usage_ping_enabled'] = true if Settings.gitlab['usage_ping_enabled'].nil?
-Settings.gitlab['prometheus_multiproc_dir'] ||= ENV['prometheus_multiproc_dir'] || 'tmp/prometheus_data_dir'
 #
 # CI

config/routes.rb

@@ -38,10 +38,10 @@ Rails.application.routes.draw do
   # Health check
   get 'health_check(/:checks)' => 'health_check#index', as: :health_check
-  scope path: '-', controller: 'health' do
-    get :liveness
-    get :readiness
-    get :metrics
+  scope path: '-' do
+    get 'liveness' => 'health#liveness'
+    get 'readiness' => 'health#readiness'
+    get 'metrics' => 'metrics#metrics'
   end
   # Koding route