Moved RackTimeout observer to a different location

Because there will be similar observer for PumaWorkerKiller,
it makes sense to keep both on better place.

config/initializers/rack_timeout.rb

@@ -18,6 +18,6 @@ if defined?(::Puma) && !Rails.env.test?
                                     wait_timeout: 90)
   end
 
-  observer = Gitlab::RackTimeoutObserver.new
+  observer = Gitlab::Cluster::RackTimeoutObserver.new
   Rack::Timeout.register_state_change_observer(:gitlab_rack_timeout, &observer.callback)
 end

lib/gitlab/cluster/rack_timeout_observer.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Cluster
+    class RackTimeoutObserver
+      def initialize
+        @counter = Gitlab::Metrics.counter(:rack_state_total, 'Number of requests in a given rack state')
+      end
+
+      # returns the Proc to be used as the observer callback block
+      def callback
+        method(:log_timeout_exception)
+      end
+
+      private
+
+      def log_timeout_exception(env)
+        info = env[::Rack::Timeout::ENV_INFO_KEY]
+        return unless info
+
+        @counter.increment(labels(info, env))
+      end
+
+      def labels(info, env)
+        params = controller_params(env) || grape_params(env) || {}
+
+        {
+          controller: params['controller'],
+          action: params['action'],
+          route: params['route'],
+          state: info.state
+        }
+      end
+
+      def controller_params(env)
+        env['action_dispatch.request.parameters']
+      end
+
+      def grape_params(env)
+        endpoint = env[Grape::Env::API_ENDPOINT]
+        route = endpoint&.route&.pattern&.origin
+        return unless route
+
+        { 'route' => route }
+      end
+    end
+  end
+end

lib/gitlab/rack_timeout_observer.rb

@@ -1,46 +0,0 @@
-# frozen_string_literal: true
-
-module Gitlab
-  class RackTimeoutObserver
-    def initialize
-      @counter = Gitlab::Metrics.counter(:rack_state_total, 'Number of requests in a given rack state')
-    end
-
-    # returns the Proc to be used as the observer callback block
-    def callback
-      method(:log_timeout_exception)
-    end
-
-    private
-
-    def log_timeout_exception(env)
-      info = env[::Rack::Timeout::ENV_INFO_KEY]
-      return unless info
-
-      @counter.increment(labels(info, env))
-    end
-
-    def labels(info, env)
-      params = controller_params(env) || grape_params(env) || {}
-
-      {
-        controller: params['controller'],
-        action: params['action'],
-        route: params['route'],
-        state: info.state
-      }
-    end
-
-    def controller_params(env)
-      env['action_dispatch.request.parameters']
-    end
-
-    def grape_params(env)
-      endpoint = env[Grape::Env::API_ENDPOINT]
-      route = endpoint&.route&.pattern&.origin
-      return unless route
-
-      { 'route' => route }
-    end
-  end
-end

spec/lib/gitlab/cluster/rack_timeout_observer_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::RackTimeoutObserver do
+describe Gitlab::Cluster::RackTimeoutObserver do
   let(:counter) { Gitlab::Metrics::NullMetric.instance }
 
   before do