Merge branch '37354-pipelines-update' into 'master'

Make sure head pippeline always corresponds with an MR

Closes #37354

See merge request gitlab-org/gitlab-ce!14358

16 files changed, 227 insertions, 50 deletions

diff --git a/app/controllers/projects/merge_requests_controller.rb b/app/controllers/projects/merge_requests_controller.rb
index abe4e5245b1..37acd1c9787 100644
--- a/app/controllers/projects/merge_requests_controller.rb
+++ b/app/controllers/projects/merge_requests_controller.rb
@@ -283,15 +283,15 @@ class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationCo
     @merge_request.update(merge_error: nil)
 
     if params[:merge_when_pipeline_succeeds].present?
-      return :failed unless @merge_request.head_pipeline
+      return :failed unless @merge_request.actual_head_pipeline
 
-      if @merge_request.head_pipeline.active?
+      if @merge_request.actual_head_pipeline.active?
         ::MergeRequests::MergeWhenPipelineSucceedsService
           .new(@project, current_user, merge_params)
           .execute(@merge_request)
 
         :merge_when_pipeline_succeeds
-      elsif @merge_request.head_pipeline.success?
+      elsif @merge_request.actual_head_pipeline.success?
         # This can be triggered when a user clicks the auto merge button while
         # the tests finish at about the same time
         @merge_request.merge_async(current_user.id, params)
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index bbc01e9677c..f2d639a3382 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -145,6 +145,13 @@ class MergeRequest < ActiveRecord::Base
     '!'
   end
 
+  # Use this method whenever you need to make sure the head_pipeline is synced with the
+  # branch head commit, for example checking if a merge request can be merged.
+  # For more information check: https://gitlab.com/gitlab-org/gitlab-ce/issues/40004
+  def actual_head_pipeline
+    head_pipeline&.sha == diff_head_sha ? head_pipeline : nil
+  end
+
   # Pattern used to extract `!123` merge request references from text
   #
   # This pattern supports cross-project references.
@@ -822,8 +829,9 @@ class MergeRequest < ActiveRecord::Base
 
   def mergeable_ci_state?
     return true unless project.only_allow_merge_if_pipeline_succeeds?
+    return true unless head_pipeline
 
-    !head_pipeline || head_pipeline.success? || head_pipeline.skipped?
+    actual_head_pipeline&.success? || actual_head_pipeline&.skipped?
   end
 
   def environments_for(current_user)
@@ -997,7 +1005,7 @@ class MergeRequest < ActiveRecord::Base
     return true if autocomplete_precheck
 
     return false unless mergeable?(skip_ci_check: true)
-    return false if head_pipeline && !(head_pipeline.success? || head_pipeline.active?)
+    return false if actual_head_pipeline && !(actual_head_pipeline.success? || actual_head_pipeline.active?)
     return false if last_diff_sha != diff_head_sha
 
     true
diff --git a/app/presenters/merge_request_presenter.rb b/app/presenters/merge_request_presenter.rb
index a25882cbb62..ab4c87c0169 100644
--- a/app/presenters/merge_request_presenter.rb
+++ b/app/presenters/merge_request_presenter.rb
@@ -163,7 +163,7 @@ class MergeRequestPresenter < Gitlab::View::Presenter::Delegated
   end
 
   def pipeline
-    @pipeline ||= head_pipeline
+    @pipeline ||= actual_head_pipeline
   end
 
   def issues_sentence(project, issues)
diff --git a/app/serializers/merge_request_entity.rb b/app/serializers/merge_request_entity.rb
index b53a49fe59e..eece9445dca 100644
--- a/app/serializers/merge_request_entity.rb
+++ b/app/serializers/merge_request_entity.rb
@@ -33,7 +33,7 @@ class MergeRequestEntity < IssuableEntity
   end
 
   expose :merge_commit_message
-  expose :head_pipeline, with: PipelineDetailsEntity, as: :pipeline
+  expose :actual_head_pipeline, with: PipelineDetailsEntity, as: :pipeline
 
   # Booleans
   expose :merge_ongoing?, as: :merge_ongoing
diff --git a/app/services/ci/create_pipeline_service.rb b/app/services/ci/create_pipeline_service.rb
index 7b9ea223d26..1e5f2ed4dd2 100644
--- a/app/services/ci/create_pipeline_service.rb
+++ b/app/services/ci/create_pipeline_service.rb
@@ -29,7 +29,7 @@ module Ci
         .new(pipeline, command, SEQUENCE)
 
       sequence.build! do |pipeline, sequence|
-        update_merge_requests_head_pipeline if pipeline.persisted?
+        schedule_head_pipeline_update
 
         if sequence.complete?
           cancel_pending_pipelines if project.auto_cancel_pending_pipelines?
@@ -38,15 +38,18 @@ module Ci
           pipeline.process!
         end
       end
+
+      pipeline
     end
 
     private
 
-    def update_merge_requests_head_pipeline
-      return unless pipeline.latest?
+    def commit
+      @commit ||= project.commit(origin_sha || origin_ref)
+    end
 
-      MergeRequest.where(source_project: @pipeline.project, source_branch: @pipeline.ref)
-        .update_all(head_pipeline_id: @pipeline.id)
+    def sha
+      commit.try(:id)
     end
 
     def cancel_pending_pipelines
@@ -69,5 +72,15 @@ module Ci
       @pipeline_created_counter ||= Gitlab::Metrics
         .counter(:pipelines_created_total, "Counter of pipelines created")
     end
+
+    def schedule_head_pipeline_update
+      related_merge_requests.each do |merge_request|
+        UpdateHeadPipelineForMergeRequestWorker.perform_async(merge_request.id)
+      end
+    end
+
+    def related_merge_requests
+      MergeRequest.where(source_project: pipeline.project, source_branch: pipeline.ref)
+    end
   end
 end
diff --git a/app/services/merge_requests/refresh_service.rb b/app/services/merge_requests/refresh_service.rb
index bf3d4855122..434dda89db0 100644
--- a/app/services/merge_requests/refresh_service.rb
+++ b/app/services/merge_requests/refresh_service.rb
@@ -76,6 +76,7 @@ module MergeRequests
         end
 
         merge_request.mark_as_unchecked
+        UpdateHeadPipelineForMergeRequestWorker.perform_async(merge_request.id)
       end
     end
 
diff --git a/app/workers/update_head_pipeline_for_merge_request_worker.rb b/app/workers/update_head_pipeline_for_merge_request_worker.rb
new file mode 100644
index 00000000000..0a2e9b63578
--- /dev/null
+++ b/app/workers/update_head_pipeline_for_merge_request_worker.rb
@@ -0,0 +1,15 @@
+class UpdateHeadPipelineForMergeRequestWorker
+  include ApplicationWorker
+
+  sidekiq_options queue: 'pipeline_default'
+
+  def perform(merge_request_id)
+    merge_request = MergeRequest.find(merge_request_id)
+    pipeline = Ci::Pipeline.where(project: merge_request.source_project, ref: merge_request.source_branch).last
+
+    return unless pipeline && pipeline.latest?
+    raise ArgumentError, 'merge request sha does not equal pipeline sha' if merge_request.diff_head_sha != pipeline.sha
+
+    merge_request.update_attribute(:head_pipeline_id, pipeline.id)
+  end
+end
diff --git a/changelogs/unreleased/37354-pipelines-update.yml b/changelogs/unreleased/37354-pipelines-update.yml
new file mode 100644
index 00000000000..2b6ddfe95ed
--- /dev/null
+++ b/changelogs/unreleased/37354-pipelines-update.yml
@@ -0,0 +1,5 @@
+---
+title: Make sure head pippeline always corresponds with the head sha of an MR
+merge_request:
+author:
+type: fixed
diff --git a/spec/controllers/projects/merge_requests_controller_spec.rb b/spec/controllers/projects/merge_requests_controller_spec.rb
index bfdad85c082..51d5d6a52b3 100644
--- a/spec/controllers/projects/merge_requests_controller_spec.rb
+++ b/spec/controllers/projects/merge_requests_controller_spec.rb
@@ -324,12 +324,12 @@ describe Projects::MergeRequestsController do
       end
 
       context 'when the pipeline succeeds is passed' do
-        def merge_when_pipeline_succeeds
-          post :merge, base_params.merge(sha: merge_request.diff_head_sha, merge_when_pipeline_succeeds: '1')
+        let!(:head_pipeline) do
+          create(:ci_empty_pipeline, project: project, sha: merge_request.diff_head_sha, ref: merge_request.source_branch, head_pipeline_of: merge_request)
         end
 
-        before do
-          create(:ci_empty_pipeline, project: project, sha: merge_request.diff_head_sha, ref: merge_request.source_branch, head_pipeline_of: merge_request)
+        def merge_when_pipeline_succeeds
+          post :merge, base_params.merge(sha: merge_request.diff_head_sha, merge_when_pipeline_succeeds: '1')
         end
 
         it 'returns :merge_when_pipeline_succeeds' do
@@ -354,6 +354,18 @@ describe Projects::MergeRequestsController do
             project.update_column(:only_allow_merge_if_pipeline_succeeds, true)
           end
 
+          context 'and head pipeline is not the current one' do
+            before do
+              head_pipeline.update(sha: 'not_current_sha')
+            end
+
+            it 'returns :failed' do
+              merge_when_pipeline_succeeds
+
+              expect(json_response).to eq('status' => 'failed')
+            end
+          end
+
           it 'returns :merge_when_pipeline_succeeds' do
             merge_when_pipeline_succeeds
 
diff --git a/spec/features/merge_requests/pipelines_spec.rb b/spec/features/merge_requests/pipelines_spec.rb
index a3fcc27cab0..307c860eac4 100644
--- a/spec/features/merge_requests/pipelines_spec.rb
+++ b/spec/features/merge_requests/pipelines_spec.rb
@@ -20,10 +20,14 @@ feature 'Pipelines for Merge Requests', :js do
       end
 
       before do
-        visit project_merge_request_path(project, merge_request)
+        merge_request.update_attribute(:head_pipeline_id, pipeline.id)
       end
 
       scenario 'user visits merge request pipelines tab' do
+        visit project_merge_request_path(project, merge_request)
+
+        expect(page.find('.ci-widget')).to have_content('pending')
+
         page.within('.merge-request-tabs') do
           click_link('Pipelines')
         end
@@ -31,6 +35,15 @@ feature 'Pipelines for Merge Requests', :js do
 
         expect(page).to have_selector('.stage-cell')
       end
+
+      scenario 'pipeline sha does not equal last commit sha' do
+        pipeline.update_attribute(:sha, '19e2e9b4ef76b422ce1154af39a91323ccc57434')
+        visit project_merge_request_path(project, merge_request)
+        wait_for_requests
+
+        expect(page.find('.ci-widget')).to have_content(
+          'Could not connect to the CI server. Please check your settings and try again')
+      end
     end
 
     context 'without pipelines' do
diff --git a/spec/models/merge_request_spec.rb b/spec/models/merge_request_spec.rb
index 728028746d8..e606fb027b5 100644
--- a/spec/models/merge_request_spec.rb
+++ b/spec/models/merge_request_spec.rb
@@ -827,20 +827,47 @@ describe MergeRequest do
     end
   end
 
-  describe '#head_pipeline' do
-    describe 'when the source project exists' do
-      it 'returns the latest pipeline' do
-        pipeline = create(:ci_empty_pipeline, project: subject.source_project, ref: 'master', status: 'running', sha: "123abc", head_pipeline_of: subject)
+  context 'head pipeline' do
+    before do
+      allow(subject).to receive(:diff_head_sha).and_return('lastsha')
+    end
+
+    describe '#head_pipeline' do
+      it 'returns nil for MR without head_pipeline_id' do
+        subject.update_attribute(:head_pipeline_id, nil)
+
+        expect(subject.head_pipeline).to be_nil
+      end
 
-        expect(subject.head_pipeline).to eq(pipeline)
+      context 'when the source project does not exist' do
+        it 'returns nil' do
+          allow(subject).to receive(:source_project).and_return(nil)
+
+          expect(subject.head_pipeline).to be_nil
+        end
       end
     end
 
-    describe 'when the source project does not exist' do
-      it 'returns nil' do
+    describe '#actual_head_pipeline' do
+      it 'returns nil for MR with old pipeline' do
+        pipeline = create(:ci_empty_pipeline, sha: 'notlatestsha')
+        subject.update_attribute(:head_pipeline_id, pipeline.id)
+
+        expect(subject.actual_head_pipeline).to be_nil
+      end
+
+      it 'returns the pipeline for MR with recent pipeline' do
+        pipeline = create(:ci_empty_pipeline, sha: 'lastsha')
+        subject.update_attribute(:head_pipeline_id, pipeline.id)
+
+        expect(subject.actual_head_pipeline).to eq(subject.head_pipeline)
+        expect(subject.actual_head_pipeline).to eq(pipeline)
+      end
+
+      it 'returns nil when source project does not exist' do
         allow(subject).to receive(:source_project).and_return(nil)
 
-        expect(subject.head_pipeline).to be_nil
+        expect(subject.actual_head_pipeline).to be_nil
       end
     end
   end
@@ -1179,7 +1206,7 @@ describe MergeRequest do
     context 'when it is only allowed to merge when build is green' do
       context 'and a failed pipeline is associated' do
         before do
-          pipeline.update(status: 'failed')
+          pipeline.update(status: 'failed', sha: subject.diff_head_sha)
           allow(subject).to receive(:head_pipeline) { pipeline }
         end
 
@@ -1188,7 +1215,7 @@ describe MergeRequest do
 
       context 'and a successful pipeline is associated' do
         before do
-          pipeline.update(status: 'success')
+          pipeline.update(status: 'success', sha: subject.diff_head_sha)
           allow(subject).to receive(:head_pipeline) { pipeline }
         end
 
@@ -1197,7 +1224,7 @@ describe MergeRequest do
 
       context 'and a skipped pipeline is associated' do
         before do
-          pipeline.update(status: 'skipped')
+          pipeline.update(status: 'skipped', sha: subject.diff_head_sha)
           allow(subject).to receive(:head_pipeline) { pipeline }
         end
 
diff --git a/spec/presenters/merge_request_presenter_spec.rb b/spec/presenters/merge_request_presenter_spec.rb
index 5e114434a67..f325d1776e4 100644
--- a/spec/presenters/merge_request_presenter_spec.rb
+++ b/spec/presenters/merge_request_presenter_spec.rb
@@ -31,7 +31,7 @@ describe MergeRequestPresenter do
       let(:pipeline) { build_stubbed(:ci_pipeline) }
 
       before do
-        allow(resource).to receive(:head_pipeline).and_return(pipeline)
+        allow(resource).to receive(:actual_head_pipeline).and_return(pipeline)
       end
 
       context 'success with warnings' do
diff --git a/spec/serializers/merge_request_entity_spec.rb b/spec/serializers/merge_request_entity_spec.rb
index f9285049c0d..1ad672fd355 100644
--- a/spec/serializers/merge_request_entity_spec.rb
+++ b/spec/serializers/merge_request_entity_spec.rb
@@ -5,22 +5,34 @@ describe MergeRequestEntity do
   let(:resource) { create(:merge_request, source_project: project, target_project: project) }
   let(:user)     { create(:user) }
 
-  let(:request) { double('request', current_user: user) }
+  let(:request) { double('request', current_user: user, project: project) }
 
   subject do
     described_class.new(resource, request: request).as_json
   end
 
-  it 'includes pipeline' do
-    req = double('request', current_user: user)
-    pipeline = build_stubbed(:ci_pipeline)
-    allow(resource).to receive(:head_pipeline).and_return(pipeline)
+  describe 'pipeline' do
+    let(:pipeline) { create(:ci_empty_pipeline, project: project, ref: resource.source_branch, sha: resource.source_branch_sha, head_pipeline_of: resource) }
 
-    pipeline_payload = PipelineDetailsEntity
-      .represent(pipeline, request: req)
-      .as_json
+    context 'when is up to date' do
+      let(:req) { double('request', current_user: user, project: project) }
 
-    expect(subject[:pipeline]).to eq(pipeline_payload)
+      it 'returns pipeline' do
+        pipeline_payload = PipelineDetailsEntity
+          .represent(pipeline, request: req)
+          .as_json
+
+        expect(subject[:pipeline]).to eq(pipeline_payload)
+      end
+    end
+
+    context 'when is not up to date' do
+      it 'returns nil' do
+        pipeline.update(sha: "not up to date")
+
+        expect(subject[:pipeline]).to be_nil
+      end
+    end
   end
 
   it 'includes issues_links' do
diff --git a/spec/services/ci/create_pipeline_service_spec.rb b/spec/services/ci/create_pipeline_service_spec.rb
index befd0faf1b6..b0de8d447a2 100644
--- a/spec/services/ci/create_pipeline_service_spec.rb
+++ b/spec/services/ci/create_pipeline_service_spec.rb
@@ -57,19 +57,39 @@ describe Ci::CreatePipelineService do
       end
 
       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)
+        let(:merge_request_1) do
+          create(:merge_request, source_branch: 'master', target_branch: "branch_1", source_project: project)
+        end
+        let(:merge_request_2) do
+          create(:merge_request, source_branch: 'master', target_branch: "branch_2", source_project: project)
+        end
 
-          merge_request_2 = create(:merge_request, source_branch: 'master',
-                                                   target_branch: "branch_2",
-                                                   source_project: project)
+        context 'when the head pipeline sha equals merge request sha' do
+          it 'updates head pipeline of each merge request' do
+            merge_request_1
+            merge_request_2
 
-          head_pipeline = execute_service
+            head_pipeline = execute_service
 
-          expect(merge_request_1.reload.head_pipeline).to eq(head_pipeline)
-          expect(merge_request_2.reload.head_pipeline).to eq(head_pipeline)
+            expect(merge_request_1.reload.head_pipeline).to eq(head_pipeline)
+            expect(merge_request_2.reload.head_pipeline).to eq(head_pipeline)
+          end
+        end
+
+        context 'when the head pipeline sha does not equal merge request sha' do
+          it 'raises the ArgumentError error from worker and does not update the head piepeline of MRs' do
+            merge_request_1
+            merge_request_2
+
+            allow_any_instance_of(Ci::Pipeline).to receive(:latest?).and_return(true)
+
+            expect { execute_service(after: 'ae73cb07c9eeaf35924a10f713b364d32b2dd34f') }.to raise_error(ArgumentError)
+
+            last_pipeline = Ci::Pipeline.last
+
+            expect(merge_request_1.reload.head_pipeline).not_to eq(last_pipeline)
+            expect(merge_request_2.reload.head_pipeline).not_to eq(last_pipeline)
+          end
         end
 
         context 'when there is no pipeline for source branch' do
@@ -106,8 +126,7 @@ describe Ci::CreatePipelineService do
                                                    target_branch: "branch_1",
                                                    source_project: project)
 
-            allow_any_instance_of(Ci::Pipeline)
-              .to receive(:latest?).and_return(false)
+            allow_any_instance_of(Ci::Pipeline).to receive(:latest?).and_return(false)
 
             execute_service
 
diff --git a/spec/services/merge_requests/refresh_service_spec.rb b/spec/services/merge_requests/refresh_service_spec.rb
index a2c05761f6b..61ec4709c59 100644
--- a/spec/services/merge_requests/refresh_service_spec.rb
+++ b/spec/services/merge_requests/refresh_service_spec.rb
@@ -74,6 +74,20 @@ describe MergeRequests::RefreshService do
       end
     end
 
+    context 'when pipeline exists for the source branch' do
+      let!(:pipeline) { create(:ci_empty_pipeline, ref: @merge_request.source_branch, project: @project, sha: @commits.first.sha)}
+
+      subject { service.new(@project, @user).execute(@oldrev, @newrev, 'refs/heads/master') }
+
+      it 'updates the head_pipeline_id for @merge_request' do
+        expect { subject }.to change { @merge_request.reload.head_pipeline_id }.from(nil).to(pipeline.id)
+      end
+
+      it 'does not update the head_pipeline_id for @fork_merge_request' do
+        expect { subject }.not_to change { @fork_merge_request.reload.head_pipeline_id }
+      end
+    end
+
     context 'push to origin repo source branch when an MR was reopened' do
       let(:refresh_service) { service.new(@project, @user) }
 
diff --git a/spec/workers/update_head_pipeline_for_merge_request_worker_spec.rb b/spec/workers/update_head_pipeline_for_merge_request_worker_spec.rb
new file mode 100644
index 00000000000..522e1566271
--- /dev/null
+++ b/spec/workers/update_head_pipeline_for_merge_request_worker_spec.rb
@@ -0,0 +1,38 @@
+require 'spec_helper'
+
+describe UpdateHeadPipelineForMergeRequestWorker do
+  describe '#perform' do
+    let(:user) { create(:user) }
+    let(:project) { create(:project, :repository) }
+    let(:merge_request) { create(:merge_request, source_project: project) }
+    let(:latest_sha) { 'b83d6e391c22777fca1ed3012fce84f633d7fed0' }
+
+    context 'when pipeline exists for the source project and branch' do
+      before do
+        create(:ci_empty_pipeline, project: project, ref: merge_request.source_branch, sha: latest_sha)
+      end
+
+      it 'updates the head_pipeline_id of the merge_request' do
+        expect { subject.perform(merge_request.id) }.to change { merge_request.reload.head_pipeline_id }
+      end
+
+      context 'when merge request sha does not equal pipeline sha' do
+        before do
+          merge_request.merge_request_diff.update(head_commit_sha: 'different_sha')
+        end
+
+        it 'does not update head_pipeline_id' do
+          expect { subject.perform(merge_request.id) }.to raise_error(ArgumentError)
+
+          expect(merge_request.reload.head_pipeline_id).to eq(nil)
+        end
+      end
+    end
+
+    context 'when pipeline does not exist for the source project and branch' do
+      it 'does not update the head_pipeline_id of the merge_request' do
+        expect { subject.perform(merge_request.id) }.not_to change { merge_request.reload.head_pipeline_id }
+      end
+    end
+  end
+end