Use a single query to get count of active VMs and Hosts

Instead of looping through all ExtManagementSystems and adding up the
counts of vms and hosts manually we can get this count in one shot by
querying for active VMs and Hosts.

app/models/host.rb

@@ -143,6 +143,8 @@ class Host < ApplicationRecord
   virtual_total :v_total_vms, :vms
   virtual_total :v_total_miq_templates, :miq_templates
 
+  scope :active, -> { where.not(:ems_id => nil) }
+
   alias_method :datastores, :storages    # Used by web-services to return datastores as the property name
 
   alias_method :parent_cluster, :ems_cluster

app/models/miq_server.rb

@@ -488,15 +488,9 @@ def self.zone_is_modifiable?
   end
 
   def self.audit_managed_resources
-    total_vms     = 0
-    total_hosts   = 0
-
-    ExtManagementSystem.all.each do |e|
-      vms     = e.all_vms_and_templates.count
-      hosts   = e.all_hosts.count
-      total_vms += vms
-      total_hosts += hosts
-    end
+    total_vms   = VmOrTemplate.active.count
+    total_hosts = Host.active.count
+
     totals = {"vms" => total_vms, "hosts" => total_hosts}
     $audit_log.info("Under Management: #{totals.to_json}")
   end

spec/models/miq_server_spec.rb

@@ -464,4 +464,19 @@
       expect(described_class.zone_is_modifiable?).to be_falsey
     end
   end
+
+  context ".audit_managed_resources" do
+    let(:ems) { FactoryBot.create(:ems_infra) }
+    let!(:active_vm) { FactoryBot.create(:vm_infra, :ext_management_system => ems) }
+    let!(:archived_vm) { FactoryBot.create(:vm_infra) }
+    let!(:active_host) { FactoryBot.create(:host, :ext_management_system => ems) }
+    let!(:archived_host) { FactoryBot.create(:host) }
+
+    it "with active and archived vms and hosts" do
+      expected_message = "Under Management: #{{"vms" => 1, "hosts" => 1}.to_json}"
+
+      expect($audit_log).to receive(:info).with(expected_message)
+      described_class.audit_managed_resources
+    end
+  end
 end