Fail upstream bridge on pipeline creation failure

Fails the upstream bridge when the downstream pipeline errors out during
creation.

ee/app/models/ee/commit_status_enums.rb

@@ -15,7 +15,8 @@ module EE
                     invalid_bridge_trigger: 1_003,
                     upstream_bridge_project_not_found: 1_004,
                     insufficient_upstream_permissions: 1_005,
-                    bridge_pipeline_is_child_pipeline: 1_006)
+                    bridge_pipeline_is_child_pipeline: 1_006,
+                    downstream_bridge_pipeline_creation_failed: 1_007)
       end
     end
   end

ee/app/presenters/ee/commit_status_presenter.rb

@@ -11,7 +11,8 @@ module EE
         downstream_bridge_project_not_found: 'This job could not be executed because downstream bridge project could not be found.',
         upstream_bridge_project_not_found: 'This job could not be executed because upstream bridge project could not be found.',
         invalid_bridge_trigger: 'This job could not be executed because downstream pipeline trigger definition is invalid.',
-        bridge_pipeline_is_child_pipeline: 'This job belongs to a child pipeline and cannot create further child pipelines.'
+        bridge_pipeline_is_child_pipeline: 'This job belongs to a child pipeline and cannot create further child pipelines.',
+        downstream_bridge_pipeline_creation_failed: 'The downstream project pipeline could not be created.'
       ).freeze
 
       EE::CommitStatusPresenter.private_constant :EE_CALLOUT_FAILURE_MESSAGES

ee/app/services/ci/create_cross_project_pipeline_service.rb

@@ -18,7 +18,7 @@ module Ci
         current_user,
         pipeline_params.fetch(:target_revision))
 
-      service.execute(
+      downstream_pipeline = service.execute(
         pipeline_params.fetch(:source), pipeline_params[:execute_params]) do |pipeline|
           @bridge.sourced_pipelines.build(
             source_pipeline: @bridge.pipeline,
@@ -28,6 +28,10 @@ module Ci
 
           pipeline.variables.build(@bridge.downstream_variables)
         end
+
+      downstream_pipeline.tap do |pipeline|
+        @bridge.drop!(:downstream_bridge_pipeline_creation_failed) if pipeline.has_yaml_errors?
+      end
     end
 
     private

ee/lib/ee/gitlab/ci/status/build/failed.rb

@@ -16,7 +16,8 @@ module EE
                 upstream_bridge_project_not_found: 'upstream project could not be found',
                 insufficient_bridge_permissions: 'no permissions to trigger downstream pipeline',
                 insufficient_upstream_permissions: 'no permissions to read upstream project',
-                bridge_pipeline_is_child_pipeline: 'creation of child pipeline not allowed from another child pipeline'
+                bridge_pipeline_is_child_pipeline: 'creation of child pipeline not allowed from another child pipeline',
+                downstream_bridge_pipeline_creation_failed: 'downstream bridge pipeline can not be created'
               ).freeze
               EE::Gitlab::Ci::Status::Build::Failed.private_constant :EE_REASONS
             end

ee/spec/services/ci/create_cross_project_pipeline_service_spec.rb

@@ -241,6 +241,33 @@ describe Ci::CreateCrossProjectPipelineService, '#execute' do
       end
     end
 
+    context 'when downstream pipeline creation errors out' do
+      let(:stub_config) { false }
+
+      before do
+        stub_ci_pipeline_yaml_file(YAML.dump(invalid: { yaml: 'error' }))
+      end
+
+      it 'creates only one new pipeline' do
+        expect { service.execute(bridge) }
+          .to change { Ci::Pipeline.count }.by(1)
+      end
+
+      it 'creates a new pipeline in the downstream project' do
+        pipeline = service.execute(bridge)
+
+        expect(pipeline.user).to eq bridge.user
+        expect(pipeline.project).to eq downstream_project
+      end
+
+      it 'drops the bridge' do
+        pipeline = service.execute(bridge)
+
+        expect(pipeline.reload).to be_failed
+        expect(bridge.reload).to be_failed
+      end
+    end
+
     context 'when bridge job has YAML variables defined' do
       before do
         bridge.yaml_variables = [{ key: 'BRIDGE', value: 'var', public: true }]