Merge branch '336311-fix-missing-sidekiq-metrics' into 'master'

Fix: Sidekiq workers delete each other's metrics

See merge request gitlab-org/gitlab!66432

config.ru

@@ -9,6 +9,12 @@ def master_process?
 end
 
 warmup do |app|
+  # The following is necessary to ensure stale Prometheus metrics don't accumulate over time.
+  # It needs to be done as early as here to ensure metrics files aren't deleted.
+  # After we hit our app in `warmup`, first metrics and corresponding files already being created,
+  # for example in `lib/gitlab/metrics/requests_rack_middleware.rb`.
+  Prometheus::CleanupMultiprocDirService.new.execute if master_process?
+
   client = Rack::MockRequest.new(app)
   client.get('/')
 end

config/initializers/7_prometheus_metrics.rb

@@ -40,9 +40,6 @@ if !Rails.env.test? && Gitlab::Metrics.prometheus_metrics_enabled?
   # When running Puma in a Single mode, `on_master_start` and `on_worker_start` are the same.
   # Thus, we order these events to run `reinitialize_on_pid_change` with `force: true` first.
   Gitlab::Cluster::LifecycleEvents.on_master_start do
-    # Ensure that stale Prometheus metrics don't accumulate over time
-    ::Prometheus::CleanupMultiprocDirService.new.execute
-
     ::Prometheus::Client.reinitialize_on_pid_change(force: true)
 
     if Gitlab::Runtime.puma?