Add feature flag for controlling the rollout

Add feature flag for controlling the decoupling rollout

app/services/ci/queue/build_queue_service.rb

@@ -47,7 +47,7 @@ module Ci
 
       def builds_for_project_runner
         relation = new_builds
-          .where(project: runner.runner_projects.select(:project_id))
+          .where(project: runner_projects_relation)
 
         order(relation)
       end
@@ -87,6 +87,14 @@ module Ci
           end
         end
       end
+
+      def runner_projects_relation
+        if ::Feature.enabled?(:ci_pending_builds_project_runners_decoupling, runner, default_enabled: :yaml)
+          runner.runner_projects.select(:project_id)
+        else
+          runner.projects.without_deleted.with_builds_enabled
+        end
+      end
     end
   end
 end

config/feature_flags/development/ci_pending_builds_project_runners_decoupling.yml

+---
+name: ci_pending_builds_project_runners_decoupling
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/70415
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/341005
+milestone: '14.4'
+type: development
+group: group::pipeline execution
+default_enabled: false

spec/services/ci/register_job_service_spec.rb

@@ -79,6 +79,16 @@ module Ci
               expect(execute(shared_runner)).to be_nil
             end
           end
+
+          context 'for specific runner' do
+            before do
+              stub_feature_flags(ci_pending_builds_project_runners_decoupling: false)
+            end
+
+            it 'does not pick a build' do
+              expect(execute(specific_runner)).to be_nil
+            end
+          end
         end
 
         context 'allow shared runners' do
@@ -228,6 +238,16 @@ module Ci
 
             it { expect(build).to be_nil }
           end
+
+          context 'and uses project runner' do
+            before do
+              stub_feature_flags(ci_pending_builds_project_runners_decoupling: false)
+            end
+
+            let(:build) { execute(specific_runner) }
+
+            it { expect(build).to be_nil }
+          end
         end
 
         context 'allow group runners' do