Support creating project from template via API

This adds support for creating projects from instance/project/group
templates via the API.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/19497

doc/api/projects.md

@@ -991,6 +991,9 @@ POST /projects/user/:user_id
 | `external_authorization_classification_label` | string | no | **(PREMIUM)** The classification label for the project |
 | `mirror` | boolean | no | **(STARTER)** Enables pull mirroring in a project |
 | `mirror_trigger_builds` | boolean | no | **(STARTER)** Pull mirroring triggers builds |
+| `template_name` | string | no | When used without `use_custom_template`, name of a [built-in project template](../gitlab-basics/create-project.md#built-in-templates). When used with `use_custom_template`, name of a custom project template |
+| `use_custom_template` | boolean | no | **(PREMIUM)** Use either custom [instance](../user/admin_area/custom_project_templates.md) or [group](../user/group/custom_project_templates.md) (with `group_with_project_templates_id`) project template |
+| `group_with_project_templates_id` | integer | no | **(PREMIUM)** For group-level custom templates, specifies ID of group from which all the custom project templates are sourced. Leave empty for instance-level templates. Requires `use_custom_template` to be true |
 
 NOTE: **Note:** If your HTTP repository is not publicly accessible,
 add authentication information to the URL: `https://username:password@gitlab.company.com/group/project.git`

ee/changelogs/unreleased/sh-create-project-from-template-api.yml

+---
+title: Support creating project from template via API
+merge_request: 16352
+author:
+type: added

ee/lib/ee/api/helpers/projects_helpers.rb

@@ -8,6 +8,13 @@ module EE
         extend ::Gitlab::Utils::Override
 
         prepended do
+          params :optional_create_project_params_ee do
+            optional :use_custom_template, type: Grape::API::Boolean, desc: "Use custom template"
+            given :use_custom_template do
+              optional :group_with_project_templates_id, type: Integer, desc: "Group ID that serves as the template source"
+            end
+          end
+
           params :optional_project_params_ee do
             optional :repository_storage, type: String, desc: 'Which storage shard the repository is on. Available only to admins'
             optional :approvals_before_merge, type: Integer, desc: 'How many approvers should approve merge request by default'

ee/spec/requests/api/projects_spec.rb

@@ -183,6 +183,65 @@ describe API::Projects do
   end
 
   describe 'POST /projects' do
+    shared_examples 'creates projects with templates' do
+      before do
+        group.add_maintainer(user)
+        stub_licensed_features(custom_project_templates: true)
+        stub_ee_application_setting(custom_project_templates_group_id: group.id)
+      end
+
+      it 'creates a project using a template' do
+        expect(ProjectExportWorker).to receive(:perform_async).and_call_original
+
+        Sidekiq::Testing.fake! do
+          expect { post api('/projects', user), params: project_params }
+            .to change { Project.count }.by(1)
+        end
+
+        expect(response).to have_gitlab_http_status(201)
+
+        project = Project.find(json_response['id'])
+        expect(project.name).to eq(new_project_name)
+      end
+    end
+
+    context 'with instance-level templates' do
+      let(:group) { create(:group) }
+      let!(:project) { create(:project, :public, namespace: group) }
+      let(:new_project_name) { "project-#{SecureRandom.hex}" }
+      let(:project_params) do
+        {
+          template_name: project.name,
+          name: new_project_name,
+          path: new_project_name,
+          use_custom_template: true,
+          namespace_id: group.id
+        }
+      end
+
+      it_behaves_like 'creates projects with templates'
+    end
+
+    context 'with group templates' do
+      let(:parent_group) { create(:group) }
+      let(:subgroup) { create(:group, :public, parent: parent_group) }
+      let(:group) { subgroup }
+      let!(:project) { create(:project, :public, namespace: subgroup) }
+      let(:new_project_name) { "project-#{SecureRandom.hex}" }
+      let(:project_params) do
+        {
+          template_name: project.name,
+          name: new_project_name,
+          path: new_project_name,
+          use_custom_template: true,
+          group_with_project_templates_id: subgroup.id,
+          namespace_id: subgroup.id
+        }
+      end
+
+      it_behaves_like 'creates projects with templates'
+    end
+
     context 'when importing with mirror attributes' do
       let(:import_url) { generate(:url) }
       let(:mirror_params) do

lib/api/helpers/projects_helpers.rb

@@ -56,6 +56,14 @@ module API
         use :optional_project_params_ee
       end
 
+      params :optional_create_project_params_ee do
+      end
+
+      params :optional_create_project_params do
+        use :optional_project_params
+        use :optional_create_project_params_ee
+      end
+
       params :optional_filter_params_ee do
       end
 

lib/api/projects.rb

@@ -68,6 +68,8 @@ module API
       params :create_params do
         optional :namespace_id, type: Integer, desc: 'Namespace ID for the new project. Default to the user namespace.'
         optional :import_url, type: String, desc: 'URL from which the project is imported'
+        optional :template_name, type: String, desc: "Name of template from which to create project"
+        mutually_exclusive :import_url, :template_name
       end
 
       def load_projects
@@ -155,7 +157,7 @@ module API
         optional :name, type: String, desc: 'The name of the project'
         optional :path, type: String, desc: 'The path of the repository'
         at_least_one_of :name, :path
-        use :optional_project_params
+        use :optional_create_project_params
         use :create_params
       end
       post do

spec/requests/api/projects_spec.rb

@@ -631,6 +631,25 @@ describe API::Projects do
       expect(project.project_feature.wiki_access_level).to eq(ProjectFeature::DISABLED)
     end
 
+    it 'creates a project using a template' do
+      expect { post api('/projects', user), params: { template_name: 'rails', name: 'rails-test' } }
+        .to change { Project.count }.by(1)
+
+      expect(response).to have_gitlab_http_status(201)
+
+      project = Project.find(json_response['id'])
+      expect(project).to be_saved
+      expect(project.import_type).to eq('gitlab_project')
+    end
+
+    it 'disallows creating a project with an import_url and template' do
+      project_params = { import_url: 'http://example.com', template_name: 'rails', name: 'rails-test' }
+      expect { post api('/projects', user), params: project_params }
+        .not_to change {  Project.count }
+
+      expect(response).to have_gitlab_http_status(400)
+    end
+
     it 'sets a project as public' do
       project = attributes_for(:project, visibility: 'public')
 
@@ -867,7 +886,7 @@ describe API::Projects do
       expect { post api("/projects/user/#{user.id}", admin), params: { name: 'Foo Project' } }.to change { Project.count }.by(1)
       expect(response).to have_gitlab_http_status(201)
 
-      project = Project.last
+      project = Project.find(json_response['id'])
 
       expect(project.name).to eq('Foo Project')
       expect(project.path).to eq('foo-project')
@@ -878,7 +897,7 @@ describe API::Projects do
         .to change { Project.count }.by(1)
       expect(response).to have_gitlab_http_status(201)
 
-      project = Project.last
+      project = Project.find(json_response['id'])
 
       expect(project.name).to eq('Foo Project')
       expect(project.path).to eq('path-project-Foo')