restrict projects ci controller to project runners

app/controllers/projects/settings/ci_cd_controller.rb

@@ -68,8 +68,13 @@ module Projects
       def define_runners_variables
         @project_runners = @project.runners.ordered
 
-        @assignable_runners = current_user.ci_authorized_runners
-          .assignable_for(project).ordered.page(params[:page]).per(20)
+        @assignable_runners = current_user
+          .ci_authorized_runners
+          .assignable_for(project)
+          .ordered
+          .belonging_to_any_project
+          .page(params[:page]).per(20)
+
         @shared_runners = ::Ci::Runner.shared.active
 
         @shared_runners_count = @shared_runners.count(:all)

app/models/ci/runner.rb

@@ -27,9 +27,13 @@ module Ci
     scope :paused, -> { where(active: false) }
     scope :online, -> { where('contacted_at > ?', contact_time_deadline) }
     scope :ordered, -> { order(id: :desc) }
+
     scope :belonging_to_project, -> (project_id) {
       joins(:runner_projects).where(ci_runner_projects: { project_id: project_id })
     }
+
+    scope :belonging_to_any_project, -> { joins(:runner_projects) }
+
     scope :belonging_to_group, -> (project_id) {
       project_groups = ::Group.joins(:projects).where(projects: { id: project_id })
       hierarchy_groups = Gitlab::GroupHierarchy.new(project_groups).base_and_ancestors
@@ -46,7 +50,8 @@ module Ci
       # FIXME: That `to_sql` is needed to workaround a weird Rails bug.
       #        Without that, placeholders would miss one and couldn't match.
       where(locked: false)
-        .where.not("id IN (#{project.runners.select(:id).to_sql})").specific
+        .where.not("ci_runners.id IN (#{project.runners.select(:id).to_sql})")
+        .specific
     end
 
     validate :tag_constraints

spec/controllers/projects/settings/ci_cd_controller_spec.rb

@@ -17,6 +17,17 @@ describe Projects::Settings::CiCdController do
       expect(response).to have_gitlab_http_status(200)
       expect(response).to render_template(:show)
     end
+
+    it 'sets assignable project runners' do
+      group = create(:group, runners: [create(:ci_runner)], parent: create(:group))
+      group.add_master(user)
+      project_runner = create(:ci_runner, projects: [create(:project, group: group)])
+      create(:ci_runner, :shared)
+
+      get :show, namespace_id: project.namespace, project_id: project
+
+      expect(assigns(:assignable_runners)).to eq [project_runner]
+    end
   end
 
   describe '#reset_cache' do

spec/models/ci/runner_spec.rb

@@ -136,6 +136,21 @@ describe Ci::Runner do
     end
   end
 
+  describe '.belonging_to_any_project' do
+    it 'returns the specific project runner' do
+      # project
+      project_project = create :project
+      project_runner = create :ci_runner, :specific, projects: [project_project]
+
+      # group
+      group = create :group
+      create :project, group: group
+      create :ci_runner, :specific, groups: [group]
+
+      expect(described_class.belonging_to_any_project).to eq [project_runner]
+    end
+  end
+
   describe '.belonging_to_group' do
     it 'returns the specific group runner' do
       # own