Add RecurringLogic to update HostResources

Add task RefreshResourceQuotaUtilization which calls determine_utilization
on every ResourceQuota. The command iterates all hosts of a ResourceQuota
and sets the host.host_resources which is used for the ResourceQuota.utilization.

This guarantees that Foreman does not miss changes to HostResources,
when they are not performed via the Foreman UI. Moreover, it increases
performance since Foreman Resource Quota does not re-compute a
ResourceQuota's utilization on host deployment and, instead, takes
the last-computed sum of HostResources.

However, this comes with the downside that HostResources might be missed
when edited out-of Foreman UI and new hosts are deployed before the
task is executed.

.rubocop.yml

@@ -43,3 +43,7 @@ Rails/SkipsModelValidations:
 
 Style/FormatStringToken:
   Enabled: false
+
+Rails/DynamicFindBy:
+  Exclude:
+    - "lib/foreman_resource_quota/engine.rb"

lib/foreman_resource_quota/async/refresh_resource_quota_utilization.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module ForemanResourceQuota
+  module Async
+    class RefreshResourceQuotaUtilization < ::Actions::EntryAction
+      include ::Actions::RecurringAction
+
+      def run
+        ResourceQuota.all.each do |quota|
+          quota.determine_utilization
+        rescue e
+          logger.error N_(format("An error occured determining the utilization of '%s'-quota: %s", quota.name, e))
+        end
+      end
+
+      def logger
+        action_logger
+      end
+
+      def rescue_strategy_for_self
+        Dynflow::Action::Rescue::Fail
+      end
+    end
+  end
+end

lib/foreman_resource_quota/engine.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'foreman_tasks'
+
 module ForemanResourceQuota
   class Engine < ::Rails::Engine
     engine_name 'foreman_resource_quota'
@@ -42,10 +44,48 @@ class Engine < ::Rails::Engine
       Rails.logger.warn "ForemanResourceQuota: skipping engine hook (#{e})"
     end
 
+    # Register ForemanTasks-based recurring logic/scheduled tasks
+    initializer 'foreman_resource_quota.register_scheduled_tasks', before: :finisher_hook do |_app|
+      action_paths = [ForemanResourceQuota::Engine.root.join('lib/foreman_resource_quota/async')]
+      ::ForemanTasks.dynflow.config.eager_load_paths.concat(action_paths)
+
+      # Skip object creation if the admin user is not present
+      # skip database manipulations while tables do not exist, like in migrations
+      if ActiveRecord::Base.connection.data_source_exists?(ForemanTasks::Task.table_name) &&
+         User.unscoped.find_by_login(User::ANONYMOUS_ADMIN).present?
+        # Register the scheduled tasks
+        ::ForemanTasks.dynflow.config.on_init(false) do |_world|
+          ForemanResourceQuota::Engine.register_scheduled_task(
+            ForemanResourceQuota::Async::RefreshResourceQuotaUtilization,
+            '0 1 * * *'
+          )
+        end
+      end
+    rescue ActiveRecord::NoDatabaseError => e
+      Rails.logger.warn "ForemanResourceQuota: skipping ForemanTasks registration hook (#{e})"
+    end
+
     initializer 'foreman_resource_quota.register_gettext', after: :load_config_initializers do |_app|
       locale_dir = File.join(File.expand_path('../..', __dir__), 'locale')
       locale_domain = 'foreman_resource_quota'
       Foreman::Gettext::Support.add_text_domain locale_domain, locale_dir
     end
+
+    # Helper to register ForemanTasks
+    def self.register_scheduled_task(task_class, cronline)
+      unless ::ForemanTasks::RecurringLogic.joins(:tasks)
+                                           .merge(::ForemanTasks::Task.where(label: task_class.name))
+                                           .exists?
+        ::ForemanTasks::RecurringLogic.transaction(isolation: :serializable) do
+          User.as_anonymous_admin do
+            recurring_logic = ::ForemanTasks::RecurringLogic.new_from_cronline(cronline)
+            recurring_logic.save!
+            recurring_logic.start(task_class)
+          end
+        rescue ActiveRecord::TransactionIsolationError => e
+          Rails.logger.warn "ForemanResourceQuota: skipping RecurringLogic registration hook (#{e})"
+        end
+      end
+    end
   end
 end