Support custom messages in the cherry-pick API

The API used for cherry-picking commits into a branch now supports the
use of a custom commit message. Leaving out a custom message results in
one being generated for you (as before).

See https://gitlab.com/gitlab-org/release-tools/-/issues/500 for more
information.

Changelog: added

app/services/commits/change_service.rb

@@ -6,6 +6,7 @@ module Commits
       super
 
       @commit = params[:commit]
+      @message = params[:message]
     end
 
     private
@@ -14,7 +15,9 @@ module Commits
       raise NotImplementedError unless repository.respond_to?(action)
 
       # rubocop:disable GitlabSecurity/PublicSend
-      message = @commit.public_send(:"#{action}_message", current_user)
+      message =
+        @message || @commit.public_send(:"#{action}_message", current_user)
+
       repository.public_send(
         action,
         current_user,

doc/api/commits.md

@@ -305,6 +305,7 @@ Parameters:
 | `sha` | string | yes | The commit hash  |
 | `branch` | string | yes | The name of the branch  |
 | `dry_run` | boolean | no | Does not commit any changes. Default is false. [Introduced in GitLab 13.3](https://gitlab.com/gitlab-org/gitlab/-/issues/231032) |
+| `message` | string | no | A custom commit message to use for the new commit. [Introduced in GitLab 14.0](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/62481)
 
 ```shell
 curl --request POST --header "PRIVATE-TOKEN: <your_access_token>" --form "branch=master" "https://gitlab.example.com/api/v4/projects/5/repository/commits/master/cherry_pick"

doc/user/project/merge_requests/cherry_pick_changes.md

@@ -100,6 +100,11 @@ To disable it:
 Feature.disable(:pick_into_project)
 ```
 
+## Related links
+
+- The [Commits API](../../../api/commits.md) enables you to add custom messages
+  to changes you cherry-pick through the API.
+
 <!-- ## Troubleshooting
 
 Include any troubleshooting steps that you can foresee. If you know beforehand what issues

lib/api/commits.rb

@@ -203,6 +203,7 @@ module API
         requires :sha, type: String, desc: 'A commit sha, or the name of a branch or tag to be cherry picked'
         requires :branch, type: String, desc: 'The name of the branch', allow_blank: false
         optional :dry_run, type: Boolean, default: false, desc: "Does not commit any changes"
+        optional :message, type: String, desc: 'A custom commit message to use for the picked commit'
       end
       post ':id/repository/commits/:sha/cherry_pick', requirements: API::COMMIT_ENDPOINT_REQUIREMENTS do
         authorize_push_to_branch!(params[:branch])
@@ -216,7 +217,8 @@ module API
           commit: commit,
           start_branch: params[:branch],
           branch_name: params[:branch],
-          dry_run: params[:dry_run]
+          dry_run: params[:dry_run],
+          message: params[:message]
         }
 
         result = ::Commits::CherryPickService

spec/requests/api/commits_spec.rb

@@ -1503,6 +1503,13 @@ RSpec.describe API::Commits do
           expect(json_response).to eq("dry_run" => "success")
           expect(project.commit(branch)).to eq(head)
         end
+
+        it 'supports the use of a custom commit message' do
+          post api(route, user), params: { branch: branch, message: 'foo' }
+
+          expect(response).to have_gitlab_http_status(:created)
+          expect(json_response["message"]).to eq('foo')
+        end
       end
 
       context 'when repository is disabled' do

spec/services/commits/cherry_pick_service_spec.rb

@@ -24,7 +24,7 @@ RSpec.describe Commits::CherryPickService do
     repository.add_branch(user, branch_name, merge_base_sha)
   end
 
-  def cherry_pick(sha, branch_name)
+  def cherry_pick(sha, branch_name, message: nil)
     commit = project.commit(sha)
 
     described_class.new(
@@ -32,7 +32,8 @@ RSpec.describe Commits::CherryPickService do
       user,
       commit: commit,
       start_branch: branch_name,
-      branch_name: branch_name
+      branch_name: branch_name,
+      message: message
     ).execute
   end
 
@@ -45,6 +46,14 @@ RSpec.describe Commits::CherryPickService do
         head = repository.find_branch(branch_name).target
         expect(head).not_to eq(merge_base_sha)
       end
+
+      it 'supports a custom commit message' do
+        result = cherry_pick(merge_commit_sha, branch_name, message: 'foo')
+        branch = repository.find_branch(branch_name)
+
+        expect(result[:status]).to eq(:success)
+        expect(branch.dereferenced_target.message).to eq('foo')
+      end
     end
 
     it_behaves_like 'successful cherry-pick'