Ensure the pipeline's iid is set before saving

Issue: gitlab.com/gitlab-org/gitlab/-/issues/325861
MR: gitlab.com/gitlab-org/gitlab/-/merge_requests/59341

app/services/ci/create_web_ide_terminal_service.rb

@@ -28,6 +28,13 @@ module Ci
     def create_pipeline!
       build_pipeline.tap do |pipeline|
         pipeline.stages << terminal_stage_seed(pipeline).to_resource
+
+        if Feature.enabled?(:ci_pipeline_ensure_iid_on_save, pipeline.project, default_enabled: :yaml)
+          # Project iid must be called outside a transaction, so we ensure it is set here
+          # otherwise it may be set within the save! which it will lock the InternalId row for the whole transaction
+          pipeline.ensure_project_iid!
+        end
+
         pipeline.save!
 
         Ci::ProcessPipelineService

config/feature_flags/development/ci_pipeline_ensure_iid_on_save.yml

+---
+name: ci_pipeline_ensure_iid_on_save
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/59341
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/327662
+milestone: '13.12'
+type: development
+group: group::code review
+default_enabled: false

spec/services/ci/create_web_ide_terminal_service_spec.rb

@@ -21,6 +21,23 @@ RSpec.describe Ci::CreateWebIdeTerminalService do
           expect(subject[:pipeline].stages.count).to eq(1)
           expect(subject[:pipeline].builds.count).to eq(1)
         end
+
+        it 'calls ensure_project_iid explicitly' do
+          expect_next_instance_of(Ci::Pipeline) do |instance|
+            expect(instance).to receive(:ensure_project_iid!).twice
+          end
+          subject
+        end
+
+        context 'when the ci_pipeline_ensure_iid_on_save feature flag is off' do
+          it 'does not call ensure_project_iid explicitly' do
+            stub_feature_flags(ci_pipeline_ensure_iid_on_save: false)
+            expect_next_instance_of(Ci::Pipeline) do |instance|
+              expect(instance).to receive(:ensure_project_iid!).once
+            end
+            subject
+          end
+        end
       end
 
       before do