Ignore connection error when changing the Elasticsearch Server URL

ee/app/services/ee/application_settings/update_service.rb

@@ -20,7 +20,7 @@ module EE
         elasticsearch_project_ids = params.delete(:elasticsearch_project_ids)
 
         if result = super
-          find_or_create_index
+          find_or_create_elasticsearch_index
           update_elasticsearch_containers(ElasticsearchIndexedNamespace, elasticsearch_namespace_ids)
           update_elasticsearch_containers(ElasticsearchIndexedProject, elasticsearch_project_ids)
         end
@@ -61,13 +61,23 @@ module EE
         current_user_cap.nil? || current_user_cap > previous_user_cap
       end
 
-      def find_or_create_index
+      def find_or_create_elasticsearch_index
         # The order of checks is important. We should not attempt to create a new index
         # unless elasticsearch_indexing is enabled
         return unless application_setting.elasticsearch_indexing
-        return if ::Gitlab::Elastic::Helper.default.index_exists?
+        return if elasticsearch_helper.index_exists?
 
-        ::Gitlab::Elastic::Helper.default.create_empty_index
+        elasticsearch_helper.create_empty_index
+      rescue Faraday::Error => e
+        log_error(e)
+      end
+
+      def elasticsearch_helper
+        @elasticsearch_helper ||= ::Gitlab::Elastic::Helper.new(client: elasticsearch_client)
+      end
+
+      def elasticsearch_client
+        ::Gitlab::Elastic::Client.build(application_setting.elasticsearch_config)
       end
     end
   end

ee/changelogs/unreleased/296032_ignore_es_connection_exception.yml

+---
+title: Ignore connection error when changing the Elasticsearch Server URL
+merge_request: 52645
+author:
+type: fixed

ee/spec/services/application_settings/update_service_spec.rb

@@ -38,7 +38,7 @@ RSpec.describe ApplicationSettings::UpdateService do
       let(:helper) { Gitlab::Elastic::Helper.new }
 
       before do
-        allow(Gitlab::Elastic::Helper).to receive(:default).and_return(helper)
+        allow(Gitlab::Elastic::Helper).to receive(:new).and_return(helper)
       end
 
       context 'index creation' do
@@ -61,6 +61,15 @@ RSpec.describe ApplicationSettings::UpdateService do
             service.execute
           end
         end
+
+        context 'when ES service is not reachable' do
+          it 'does not throw exception' do
+            expect(helper).to receive(:index_exists?).and_raise(Faraday::ConnectionFailed, nil)
+            expect(helper).not_to receive(:create_empty_index)
+
+            expect { service.execute }.not_to raise_error
+          end
+        end
       end
     end