Set head pipeline when creating merge requests

app/services/ci/create_pipeline_service.rb

@@ -61,6 +61,16 @@ module Ci
 
     private
 
+    def update_merge_requests_head_pipeline
+      merge_requests = MergeRequest.where(source_branch: @pipeline.ref, source_project: @pipeline.project)
+
+      merge_requests = merge_requests.select do |mr|
+        mr.diff_head_sha == @pipeline.sha
+      end
+
+      MergeRequest.where(id: merge_requests).update_all(head_pipeline_id: @pipeline.id)
+    end
+
     def skip_ci?
       return false unless pipeline.git_commit_message
       pipeline.git_commit_message =~ /\[(ci[ _-]skip|skip[ _-]ci)\]/i
@@ -118,17 +128,6 @@ module Ci
       origin_sha && origin_sha != Gitlab::Git::BLANK_SHA
     end
 
-    def update_merge_requests_head_pipeline
-      merge_requests = MergeRequest.where(source_branch: @pipeline.ref, source_project: @pipeline.project)
-
-      merge_requests_ids =
-        merge_requests.select do |mr|
-          mr.diff_head_sha == @pipeline.sha
-        end.map(&:id)
-
-      MergeRequest.where(id: merge_requests_ids).update_all(head_pipeline_id: @pipeline.id)
-    end
-
     def error(message, save: false)
       pipeline.errors.add(:base, message)
       pipeline.drop if save

app/services/merge_requests/create_service.rb

@@ -11,7 +11,9 @@ module MergeRequests
 
       merge_request = MergeRequest.new
       merge_request.source_project = source_project
+      merge_request.source_branch = params[:source_branch]
       merge_request.merge_params['force_remove_source_branch'] = params.delete(:force_remove_source_branch)
+      merge_request.head_pipeline = head_pipeline_for(merge_request)
 
       create(merge_request)
     end
@@ -22,5 +24,21 @@ module MergeRequests
       todo_service.new_merge_request(issuable, current_user)
       issuable.cache_merge_request_closes_issues!(current_user)
     end
+
+    private
+
+    def head_pipeline_for(merge_request)
+      return unless merge_request.source_project
+
+      sha = merge_request.source_branch_head&.id
+
+      return unless sha
+
+      pipelines =
+        Ci::Pipeline.where(ref: merge_request.source_branch, project_id: merge_request.source_project.id, sha: sha).
+        order(id: :desc)
+
+      pipelines.first
+    end
   end
 end

changelogs/unreleased/issue_32225_2.yml

 ---
-title: Sanity check for pipeline sha before saving merge request pipeline id
+title: Handle head pipeline when creating merge requests
 merge_request:
 author:

spec/services/ci/create_pipeline_service_spec.rb

@@ -36,7 +36,7 @@ describe Ci::CreatePipelineService, services: true do
         expect(pipeline.builds.first).to be_kind_of(Ci::Build)
       end
 
-      context '#update_merge_requests_head_pipeline' do
+      context 'when merge requests already exist for this source branch' do
         it 'updates head pipeline of each merge request' do
           merge_request_1 = create(:merge_request, source_branch: 'master', target_branch: "branch_1", source_project: project)
           merge_request_2 = create(:merge_request, source_branch: 'master', target_branch: "branch_2", source_project: project)

spec/services/merge_requests/create_service_spec.rb

@@ -75,6 +75,37 @@ describe MergeRequests::CreateService, services: true do
           expect(Todo.where(attributes).count).to eq 1
         end
       end
+
+      context 'when head pipelines already exist for merge request source branch' do
+        let(:sha) { project.commit(opts[:source_branch]).id }
+        let!(:pipeline_1) { create(:ci_pipeline, project: project, ref: opts[:source_branch], project_id: project.id, sha: sha) }
+        let!(:pipeline_2) { create(:ci_pipeline, project: project, ref: opts[:source_branch], project_id: project.id, sha: sha) }
+        let!(:pipeline_3) { create(:ci_pipeline, project: project, ref: "other_branch", project_id: project.id) }
+
+        before do
+          project.merge_requests.
+            where(source_branch: opts[:source_branch], target_branch: opts[:target_branch]).
+            destroy_all
+        end
+
+        it 'sets head pipeline' do
+          merge_request = service.execute
+
+          expect(merge_request.head_pipeline).to eq(pipeline_2)
+          expect(merge_request).to be_persisted
+        end
+
+        context 'when merge request head commit sha does not match pipeline sha' do
+          it 'sets the head pipeline correctly' do
+            pipeline_2.update(sha: 1234)
+
+            merge_request = service.execute
+
+            expect(merge_request.head_pipeline).to eq(pipeline_1)
+            expect(merge_request).to be_persisted
+          end
+        end
+      end
     end
 
     it_behaves_like 'new issuable record that supports slash commands' do