Create master branch first if project is repository-less

app/controllers/projects/branches_controller.rb

 class Projects::BranchesController < Projects::ApplicationController
   include ActionView::Helpers::SanitizeHelper
   include SortingHelper
+  include ProjectsHelper
+
   # Authorize
-  before_action :require_non_empty_project
+  before_action :require_non_empty_project, except: :create
   before_action :authorize_download_code!
   before_action :authorize_push_code!, only: [:new, :create, :destroy, :destroy_all_merged]
 
@@ -32,6 +34,8 @@ class Projects::BranchesController < Projects::ApplicationController
     branch_name = sanitize(strip_tags(params[:branch_name]))
     branch_name = Addressable::URI.unescape(branch_name)
 
+    is_redirect_to_autodeploy_needed = project.empty_repo? && project.deployment_services.present?
+
     result = CreateBranchService.new(project, current_user).
         execute(branch_name, ref)
 
@@ -42,8 +46,16 @@ class Projects::BranchesController < Projects::ApplicationController
 
     if result[:status] == :success
       @branch = result[:branch]
-      redirect_to namespace_project_tree_path(@project.namespace, @project,
-                                              @branch.name)
+
+      if is_redirect_to_autodeploy_needed
+        redirect_to(
+          url_to_autodeploy_setup(project, branch_name),
+          notice: "Branch \"#{sanitize(branch_name)}\" was created. To set up auto deploy, \
+            choose a GitLab CI Yaml template and commit your changes. #{view_context.link_to_autodeploy_doc}".html_safe)
+      else
+        redirect_to namespace_project_tree_path(@project.namespace, @project,
+                                                @branch.name)
+      end
     else
       @error = result[:message]
       render action: 'new'
@@ -76,7 +88,7 @@ class Projects::BranchesController < Projects::ApplicationController
       ref_escaped = sanitize(strip_tags(params[:ref]))
       Addressable::URI.unescape(ref_escaped)
     else
-      @project.default_branch
+      @project.default_branch || 'master'
     end
   end
 end

app/helpers/projects_helper.rb

@@ -150,6 +150,10 @@ module ProjectsHelper
     ).html_safe
   end
 
+  def link_to_autodeploy_doc
+    link_to 'About auto deploy', help_page_path('ci/autodeploy/index'), target: '_blank'
+  end
+
   private
 
   def repo_children_classes(field)
@@ -268,6 +272,18 @@ module ProjectsHelper
     )
   end
 
+  def url_to_autodeploy_setup(project, branch_name)
+    namespace_project_new_blob_path(
+      project.namespace,
+      project,
+      branch_name,
+      file_name: '.gitlab-ci.yml',
+      commit_message: 'Set up auto deploy',
+      target_branch: branch_name,
+      context: 'autodeploy'
+    )
+  end
+
   def add_koding_stack_path(project)
     namespace_project_new_blob_path(
       project.namespace,

app/services/create_branch_service.rb

 class CreateBranchService < BaseService
   def execute(branch_name, ref)
+    create_master_branch if project.empty_repo?
+
     result = ValidateNewBranchService.new(project, current_user)
       .execute(branch_name)
 
@@ -19,4 +21,16 @@ class CreateBranchService < BaseService
   def success(branch)
     super().merge(branch: branch)
   end
+
+  private
+
+  def create_master_branch
+    project.repository.commit_file(
+      current_user,
+      '/README.md',
+      '',
+      message: 'Add README.md',
+      branch_name: 'master',
+      update: false)
+  end
 end

spec/controllers/projects/branches_controller_spec.rb

@@ -68,7 +68,7 @@ describe Projects::BranchesController do
 
     describe "created from the new branch button on issues" do
       let(:branch) { "1-feature-branch" }
-      let!(:issue) { create(:issue, project: project) }
+      let(:issue) { create(:issue, project: project) }
 
       before do
         sign_in(user)
@@ -95,6 +95,49 @@ describe Projects::BranchesController do
           issue_iid: issue.iid
       end
 
+      context 'repository-less project' do
+        let(:project) { create :empty_project }
+
+        it 'redirects to newly created branch' do
+          result = { status: :success, branch: double(name: branch) }
+
+          expect_any_instance_of(CreateBranchService).to receive(:execute).and_return(result)
+          expect(SystemNoteService).to receive(:new_issue_branch).and_return(true)
+
+          post :create,
+            namespace_id: project.namespace.to_param,
+            project_id: project.to_param,
+            branch_name: branch,
+            issue_iid: issue.iid
+
+          expect(response).to redirect_to namespace_project_tree_path(project.namespace, project, branch)
+        end
+
+        it 'redirects to autodeploy setup page' do
+          result = { status: :success, branch: double(name: branch) }
+
+          project.create_kubernetes_service(
+            active: true,
+            properties: {
+              namespace: project.path,
+              api_url: 'https://kubernetes.example.com',
+              token: 'a' * 40,
+            }
+          )
+
+          expect_any_instance_of(CreateBranchService).to receive(:execute).and_return(result)
+          expect(SystemNoteService).to receive(:new_issue_branch).and_return(true)
+
+          post :create,
+            namespace_id: project.namespace.to_param,
+            project_id: project.to_param,
+            branch_name: branch,
+            issue_iid: issue.iid
+
+          expect(response.location).to include(namespace_project_new_blob_path(project.namespace, project, branch))
+        end
+      end
+
       context 'without issue feature access' do
         before do
           project.update!(visibility_level: Gitlab::VisibilityLevel::PUBLIC)