Pass "skip_ci" parameter to MR rebase API

* Let `skip_ci` to be passed to the API endpoint
* Add doc entry
* Add changelog entry

app/models/merge_request.rb

@@ -449,7 +449,7 @@ class MergeRequest < ApplicationRecord
 
   # Set off a rebase asynchronously, atomically updating the `rebase_jid` of
   # the MR so that the status of the operation can be tracked.
-  def rebase_async(user_id)
+  def rebase_async(user_id, skip_ci: false)
     with_rebase_lock do
       raise ActiveRecord::StaleObjectError if !open? || rebase_in_progress?
 
@@ -458,7 +458,7 @@ class MergeRequest < ApplicationRecord
       # attribute is set *and* that the sidekiq job is still running. So a JID
       # for a completed RebaseWorker is equivalent to a nil JID.
       jid = Sidekiq::Worker.skipping_transaction_check do
-        RebaseWorker.perform_async(id, user_id)
+        RebaseWorker.perform_async(id, user_id, skip_ci)
       end
 
       update_column(:rebase_jid, jid)

app/services/merge_requests/rebase_service.rb

@@ -8,8 +8,9 @@ module MergeRequests
 
     attr_reader :merge_request
 
-    def execute(merge_request)
+    def execute(merge_request, skip_ci: false)
       @merge_request = merge_request
+      @skip_ci = skip_ci
 
       if rebase
         success
@@ -25,7 +26,7 @@ module MergeRequests
         return false
       end
 
-      repository.rebase(current_user, merge_request)
+      repository.rebase(current_user, merge_request, skip_ci: @skip_ci)
 
       true
     rescue => e

app/workers/rebase_worker.rb

@@ -7,12 +7,12 @@ class RebaseWorker
 
   feature_category :source_code_management
 
-  def perform(merge_request_id, current_user_id)
+  def perform(merge_request_id, current_user_id, skip_ci = false)
     current_user = User.find(current_user_id)
     merge_request = MergeRequest.find(merge_request_id)
 
     MergeRequests::RebaseService
       .new(merge_request.source_project, current_user)
-      .execute(merge_request)
+      .execute(merge_request, skip_ci: skip_ci)
   end
 end

changelogs/unreleased/allow-skip-ci-on-rebase.yml

+---
+title: Allow "skip_ci" flag to be passed to rebase operation
+merge_request: 22800
+author:
+type: added

doc/api/merge_requests.md

@@ -1613,6 +1613,7 @@ PUT /projects/:id/merge_requests/:merge_request_iid/rebase
 | ---------           | ----    | -------- | -----------                          |
 | `id`                | integer/string | yes      | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding) owned by the authenticated user                  |
 | `merge_request_iid` | integer | yes      | The internal ID of the merge request |
+| `skip_ci`           | boolean | no       | Set to `true` to skip creating a CI pipeline |
 
 ```bash
 curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/projects/76/merge_requests/1/rebase

ee/spec/controllers/projects/merge_requests_controller_spec.rb

@@ -366,7 +366,7 @@ describe Projects::MergeRequestsController do
     end
 
     def expect_rebase_worker_for(user)
-      expect(RebaseWorker).to receive(:perform_async).with(merge_request.id, user.id)
+      expect(RebaseWorker).to receive(:perform_async).with(merge_request.id, user.id, false)
     end
 
     context 'approvals pending' do

lib/api/merge_requests.rb

@@ -439,12 +439,15 @@ module API
       desc 'Rebase the merge request against its target branch' do
         detail 'This feature was added in GitLab 11.6'
       end
+      params do
+        optional :skip_ci, type: Boolean, desc: 'Do not create CI pipeline'
+      end
       put ':id/merge_requests/:merge_request_iid/rebase' do
         merge_request = find_project_merge_request(params[:merge_request_iid])
 
         authorize_push_to_merge_request!(merge_request)
 
-        merge_request.rebase_async(current_user.id)
+        merge_request.rebase_async(current_user.id, skip_ci: params[:skip_ci])
 
         status :accepted
         present rebase_in_progress: merge_request.rebase_in_progress?

lib/gitlab/gitaly_client/operation_service.rb

@@ -256,7 +256,8 @@ module Gitlab
               branch: encode_binary(branch),
               branch_sha: branch_sha,
               remote_repository: remote_repository.gitaly_repository,
-              remote_branch: encode_binary(remote_branch)
+              remote_branch: encode_binary(remote_branch),
+              skip_ci: skip_ci
             )
           )
         )

spec/controllers/projects/merge_requests_controller_spec.rb

@@ -1376,7 +1376,7 @@ describe Projects::MergeRequestsController do
     end
 
     def expect_rebase_worker_for(user)
-      expect(RebaseWorker).to receive(:perform_async).with(merge_request.id, user.id)
+      expect(RebaseWorker).to receive(:perform_async).with(merge_request.id, user.id, false)
     end
 
     context 'successfully' do

spec/models/merge_request_spec.rb

@@ -2022,7 +2022,7 @@ describe MergeRequest do
     it 'atomically enqueues a RebaseWorker job and updates rebase_jid' do
       expect(RebaseWorker)
         .to receive(:perform_async)
-        .with(merge_request.id, user_id)
+        .with(merge_request.id, user_id, false)
         .and_return(rebase_jid)
 
       expect(merge_request).to receive(:expire_etag_cache)

spec/requests/api/merge_requests_spec.rb

@@ -2222,16 +2222,34 @@ describe API::MergeRequests do
   end
 
   describe 'PUT :id/merge_requests/:merge_request_iid/rebase' do
-    it 'enqueues a rebase of the merge request against the target branch' do
-      Sidekiq::Testing.fake! do
-        put api("/projects/#{project.id}/merge_requests/#{merge_request.iid}/rebase", user)
+    context 'when rebase can be performed' do
+      it 'enqueues a rebase of the merge request against the target branch' do
+        Sidekiq::Testing.fake! do
+          expect do
+            put api("/projects/#{project.id}/merge_requests/#{merge_request.iid}/rebase", user)
+          end.to change { RebaseWorker.jobs.size }.by(1)
+        end
+
+        expect(response).to have_gitlab_http_status(202)
+        expect(merge_request.reload).to be_rebase_in_progress
+        expect(json_response['rebase_in_progress']).to be(true)
       end
 
-      expect(response).to have_gitlab_http_status(202)
-      expect(RebaseWorker.jobs.size).to eq(1)
+      context 'when skip_ci parameter is set' do
+        it 'enqueues a rebase of the merge request with skip_ci flag set' do
+          expect(RebaseWorker).to receive(:perform_async).with(merge_request.id, user.id, true).and_call_original
 
-      expect(merge_request.reload).to be_rebase_in_progress
-      expect(json_response['rebase_in_progress']).to be(true)
+          Sidekiq::Testing.fake! do
+            expect do
+              put api("/projects/#{project.id}/merge_requests/#{merge_request.iid}/rebase", user), params: { skip_ci: true }
+            end.to change { RebaseWorker.jobs.size }.by(1)
+          end
+
+          expect(response).to have_gitlab_http_status(202)
+          expect(merge_request.reload).to be_rebase_in_progress
+          expect(json_response['rebase_in_progress']).to be(true)
+        end
+      end
     end
 
     it 'returns 403 if the user cannot push to the branch' do

spec/services/merge_requests/rebase_service_spec.rb

@@ -15,6 +15,7 @@ describe MergeRequests::RebaseService do
   end
   let(:project) { merge_request.project }
   let(:repository) { project.repository.raw }
+  let(:skip_ci) { false }
 
   subject(:service) { described_class.new(project, user, {}) }
 
@@ -115,7 +116,7 @@ describe MergeRequests::RebaseService do
     context 'valid params' do
       shared_examples_for 'a service that can execute a successful rebase' do
         before do
-          service.execute(merge_request)
+          service.execute(merge_request, skip_ci: skip_ci)
         end
 
         it 'rebases source branch' do
@@ -155,6 +156,12 @@ describe MergeRequests::RebaseService do
         it_behaves_like 'a service that can execute a successful rebase'
       end
 
+      context 'when skip_ci flag is set' do
+        let(:skip_ci) { true }
+
+        it_behaves_like 'a service that can execute a successful rebase'
+      end
+
       context 'fork' do
         describe 'successful fork rebase' do
           let(:forked_project) do