Add build_git_strategy attribute to project API

We map the boolean to the string 'fetch' or 'clone', to be more
explicit.

app/models/concerns/project_api_compatibility.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+# Add methods used by the projects API
+module ProjectAPICompatibility
+  extend ActiveSupport::Concern
+
+  def build_git_strategy=(value)
+    write_attribute(:build_allow_git_fetch, value == 'fetch')
+  end
+end

app/models/project.rb

@@ -15,6 +15,7 @@ class Project < ApplicationRecord
   include CaseSensitivity
   include TokenAuthenticatable
   include ValidAttribute
+  include ProjectAPICompatibility
   include ProjectFeaturesCompatibility
   include SelectForProjectAuthorization
   include Presentable

doc/api/projects.md

@@ -733,6 +733,7 @@ POST /projects
 | `tag_list`    | array   | no       | The list of tags for a project; put array of tags, that should be finally assigned to a project |
 | `avatar`    | mixed   | no      | Image file for avatar of the project                |
 | `printing_merge_request_link_enabled` | boolean | no | Show link to create/view merge request when pushing from the command line |
+| `build_git_strategy` | string | no | The Git strategy. Defaults to `fetch` |
 | `ci_config_path` | string | no | The path to CI config file |
 | `repository_storage` | string | no | Which storage shard the repository is on. Available only to admins |
 | `approvals_before_merge` | integer | no | **[STARTER]** How many approvers should approve merge requests by default |
@@ -784,6 +785,7 @@ POST /projects/user/:user_id
 | `tag_list`    | array   | no       | The list of tags for a project; put array of tags, that should be finally assigned to a project |
 | `avatar`    | mixed   | no      | Image file for avatar of the project                |
 | `printing_merge_request_link_enabled` | boolean | no | Show link to create/view merge request when pushing from the command line |
+| `build_git_strategy` | string | no | The Git strategy. Defaults to `fetch` |
 | `ci_config_path` | string | no | The path to CI config file |
 | `repository_storage` | string | no | Which storage shard the repository is on. Available only to admins |
 | `approvals_before_merge` | integer | no | **[STARTER]** How many approvers should approve merge requests by default |
@@ -834,6 +836,7 @@ PUT /projects/:id
 | `request_access_enabled` | boolean | no | Allow users to request member access |
 | `tag_list`    | array   | no       | The list of tags for a project; put array of tags, that should be finally assigned to a project |
 | `avatar`    | mixed   | no      | Image file for avatar of the project                |
+| `build_git_strategy` | string | no | The Git strategy. Defaults to `fetch` |
 | `ci_config_path` | string | no | The path to CI config file |
 | `ci_default_git_depth` | integer | no | Default number of revisions for [shallow cloning](../user/project/pipelines/settings.md#git-shallow-clone) |
 | `repository_storage` | string | no | Which storage shard the repository is on. Available only to admins |

lib/api/entities.rb

@@ -275,6 +275,9 @@ module API
       expose :runners_token, if: lambda { |_project, options| options[:user_can_admin_project] }
       expose :ci_default_git_depth
       expose :public_builds, as: :public_jobs
+      expose :build_git_strategy, if: lambda { |project, options| options[:user_can_admin_project] } do |project, options|
+        project.build_allow_git_fetch ? 'fetch' : 'clone'
+      end
       expose :ci_config_path, if: -> (project, options) { Ability.allowed?(options[:current_user], :download_code, project) }
       expose :shared_with_groups do |project, options|
         SharedGroup.represent(project.project_group_links, options)

lib/api/helpers/projects_helpers.rb

@@ -8,6 +8,7 @@ module API
 
       params :optional_project_params_ce do
         optional :description, type: String, desc: 'The description of the project'
+        optional :build_git_strategy, type: String, values: %w(fetch clone), desc: 'The Git strategy. Defaults to `fetch`'
         optional :ci_config_path, type: String, desc: 'The path to CI config file. Defaults to `.gitlab-ci.yml`'
 
         # TODO: remove in API v5, replaced by *_access_level
@@ -58,6 +59,7 @@ module API
 
       def self.update_params_at_least_one_of
         [
+          :build_git_strategy,
           :builds_access_level,
           :ci_config_path,
           :container_registry_enabled,

spec/models/concerns/project_api_compatibility_spec.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe ProjectAPICompatibility do
+  let(:project) { create(:project) }
+
+  it "converts build_git_strategy=fetch to build_allow_git_fetch=true" do
+    project.update!(:build_git_strategy, 'fetch')
+    expect(project.build_allow_git_fetch).to eq(true)
+  end
+
+  it "converts build_git_strategy=clone to build_allow_git_fetch=false" do
+    project.update!(:build_git_strategy, 'clone')
+    expect(project.build_allow_git_fetch).to eq(false)
+  end
+end

spec/requests/api/projects_spec.rb

@@ -1929,6 +1929,24 @@ describe API::Projects do
         expect(json_response['builds_access_level']).to eq('private')
       end
 
+      it 'updates build_git_strategy' do
+        project_param = { build_git_strategy: 'clone' }
+
+        put api("/projects/#{project3.id}", user), params: project_param
+
+        expect(response).to have_gitlab_http_status(200)
+
+        expect(json_response['build_git_strategy']).to eq('clone')
+      end
+
+      it 'rejects to update build_git_strategy when build_git_strategy is invalid' do
+        project_param = { build_git_strategy: 'invalid' }
+
+        put api("/projects/#{project3.id}", user), params: project_param
+
+        expect(response).to have_gitlab_http_status(400)
+      end
+
       it 'updates merge_method' do
         project_param = { merge_method: 'ff' }