Don't start Prometheus Exporter unless PROMETHEUS_EXPORTER_ENABLED is set to true

config/initializers/prometheus.rb

@@ -1,5 +1,5 @@
 # in config/initializers/prometheus.rb
-if Rails.env != "test"
+if Rails.env != "test" && ENV['PROMETHEUS_EXPORTER_ENABLED'].to_s == 'true'
   require 'prometheus_exporter/middleware'
   require 'prometheus_exporter/instrumentation'
 

config/initializers/sidekiq.rb

@@ -5,6 +5,7 @@ Sidekiq.configure_server do |config|
 
   require 'prometheus_exporter/instrumentation'
 
+  if ENV['PROMETHEUS_EXPORTER_ENABLED'].to_s == 'true'
     config.server_middleware do |chain|
       chain.add PrometheusExporter::Instrumentation::Sidekiq
     end
@@ -17,6 +18,7 @@ Sidekiq.configure_server do |config|
       PrometheusExporter::Instrumentation::SidekiqQueue.start
       PrometheusExporter::Instrumentation::SidekiqStats.start
     end
+  end
 end
 
 Sidekiq.configure_client do |config|

config/puma.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'prometheus_exporter/instrumentation'
-
 # Puma can serve each request in a thread from an internal thread pool.
 # The `threads` method setting takes two numbers: a minimum and maximum.
 # Any libraries that use thread pools should be configured to match
@@ -49,4 +47,9 @@ plugin :tmp_restart
 # Prometheus exporter
 #
 # optional check, avoids spinning up and down threads per worker
-PrometheusExporter::Instrumentation::Puma.start unless PrometheusExporter::Instrumentation::Puma.started?
+
+if ENV['PROMETHEUS_EXPORTER_ENABLED'].to_s == 'true'
+  require 'prometheus_exporter/instrumentation'
+
+  PrometheusExporter::Instrumentation::Puma.start unless PrometheusExporter::Instrumentation::Puma.started?
+end