diff --git a/app/views/admin/application_settings/_form.html.haml b/app/views/admin/application_settings/_form.html.haml
index d552704df88056bd3612f409012f349f66da2205..d30ab0c0eaab6ac4740786712f88c7778f04178c 100644
--- a/app/views/admin/application_settings/_form.html.haml
+++ b/app/views/admin/application_settings/_form.html.haml
@@ -310,6 +310,10 @@
           = f.label :prometheus_metrics_enabled do
             = f.check_box :prometheus_metrics_enabled
             Enable Prometheus Metrics
+            - if !Gitlab::Metrics.metrics_folder_present?
+              .help-block
+                %strong.cred WARNING:
+                Environment variable `prometheus_multiproc_dir` does not exist or is not pointing to a valid directory.
 
   %fieldset
     %legend Background Jobs
diff --git a/config.ru b/config.ru
index 89aba462f1961909212c00858824510cff3f9120..065ce59932f2ff8c832589bd20e19ae4defc4394 100644
--- a/config.ru
+++ b/config.ru
@@ -15,9 +15,6 @@ if defined?(Unicorn)
   end
 end
 
-# set default directory for multiproces metrics gathering
-ENV['prometheus_multiproc_dir'] ||= 'tmp/prometheus_multiproc_dir'
-
 require ::File.expand_path('../config/environment',  __FILE__)
 
 map ENV['RAILS_RELATIVE_URL_ROOT'] || "/" do
diff --git a/config/boot.rb b/config/boot.rb
index 17a7114837028aa9ac90e9fea07db8de232ccb17..7e8de3b6da3e7e7fc54b65c75d7d238ece8990b6 100644
--- a/config/boot.rb
+++ b/config/boot.rb
@@ -5,6 +5,11 @@
 
 require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
 
+# set default directory for multiproces metrics gathering
+unless ENV['RAILS_ENV'] == 'production' || ENV['RAILS_ENV'] == 'staging'
+  ENV['prometheus_multiproc_dir'] ||= 'tmp/prometheus_multiproc_dir'
+end
+
 # Default Bootsnap configuration from https://github.com/Shopify/bootsnap#usage
 require 'bootsnap'
 Bootsnap.setup(
diff --git a/lib/gitlab/metrics/prometheus.rb b/lib/gitlab/metrics/prometheus.rb
index 606865093324fe7285fd4cbae746b220e7180eed..c7a2ae03508a598e3356692ba0b609f69c0deadb 100644
--- a/lib/gitlab/metrics/prometheus.rb
+++ b/lib/gitlab/metrics/prometheus.rb
@@ -5,8 +5,12 @@ module Metrics
     module Prometheus
       include Gitlab::CurrentSettings
 
+      def metrics_folder_present?
+        ENV.has_key?('prometheus_multiproc_dir') && ::Dir.exist?(ENV['prometheus_multiproc_dir'])
+      end
+
       def prometheus_metrics_enabled?
-        @prometheus_metrics_enabled ||= current_application_settings[:prometheus_metrics_enabled] || false
+        @prometheus_metrics_enabled ||= metrics_folder_present? || current_application_settings[:prometheus_metrics_enabled] || false
       end
 
       def registry