Resolve "PrometheusService validation bug prevents saving for non-manual configurations"

app/models/project_services/prometheus_service.rb

@@ -13,9 +13,9 @@ class PrometheusService < MonitoringService
   # to allow localhost URLs when the following conditions are true:
   # 1. project is the self-monitoring project.
   # 2. api_url is the internal Prometheus URL.
-  with_options presence: true, if: :manual_configuration? do
-    validates :api_url, public_url: true, unless: proc { |object| object.allow_local_api_url? }
-    validates :api_url, url: true, if: proc { |object| object.allow_local_api_url? }
+  with_options presence: true do
+    validates :api_url, public_url: true, if: ->(object) { object.manual_configuration? && !object.allow_local_api_url? }
+    validates :api_url, url: true, if: ->(object) { object.manual_configuration? && object.allow_local_api_url? }
   end
 
   before_save :synchronize_service_state

spec/models/project_services/prometheus_service_spec.rb

@@ -48,6 +48,18 @@ describe PrometheusService, :use_clean_rails_memory_store_caching do
 
       it 'does not validate presence of api_url' do
         expect(service).not_to validate_presence_of(:api_url)
+        expect(service.valid?).to eq(true)
+      end
+
+      context 'local connections allowed' do
+        before do
+          stub_application_setting(allow_local_requests_from_web_hooks_and_services: true)
+        end
+
+        it 'does not validate presence of api_url' do
+          expect(service).not_to validate_presence_of(:api_url)
+          expect(service.valid?).to eq(true)
+        end
       end
     end