Unify into :group_clusters feature flag

With this MR, group clusters is now functional, so default to enabled.

Have a single setting on the root ancestor group to enabled or disable
group clusters feature as a whole

app/controllers/groups/clusters_controller.rb

@@ -3,8 +3,8 @@
 class Groups::ClustersController < Clusters::ClustersController
   include ControllerWithCrossProjectAccessCheck
-  prepend_before_action :check_group_clusters_feature_flag!
   prepend_before_action :group
+  prepend_before_action :check_group_clusters_feature_flag!
   requires_cross_project_access
   layout 'group'
@@ -20,6 +20,10 @@ class Groups::ClustersController < Clusters::ClustersController
   end
   def check_group_clusters_feature_flag!
-    render_404 unless Feature.enabled?(:group_clusters)
+    render_404 unless group_clusters_enabled?
+  end
+
+  def group_clusters_enabled?
+    group.group_clusters_enabled?
   end
 end

app/helpers/groups_helper.rb

@@ -140,7 +140,7 @@ module GroupsHelper
       can?(current_user, "read_group_#{resource}".to_sym, @group)
     end
-    if can?(current_user, :read_cluster, @group) && Feature.enabled?(:group_clusters)
+    if can?(current_user, :read_cluster, @group) && @group.group_clusters_enabled?
       links << :kubernetes
     end

app/models/concerns/deployment_platform.rb

@@ -25,7 +25,7 @@ module DeploymentPlatform
   end
   def find_group_cluster_platform_kubernetes_with_feature_guard(environment: nil)
-    return unless Feature.enabled?(:deploy_group_clusters, default_enabled: true)
+    return unless group_clusters_enabled?
     find_group_cluster_platform_kubernetes(environment: environment)
   end

app/models/group.rb

@@ -400,6 +400,10 @@ class Group < Namespace
     ensure_runners_token!
   end
+  def group_clusters_enabled?
+    Feature.enabled?(:group_clusters, root_ancestor, default_enabled: true)
+  end
+
   private
   def update_two_factor_requirement

app/models/namespace.rb

@@ -243,7 +243,7 @@ class Namespace < ActiveRecord::Base
   end
   def root_ancestor
-    ancestors.reorder(nil).find_by(parent_id: nil)
+    self_and_ancestors.reorder(nil).find_by(parent_id: nil)
   end
   def subgroup?

app/models/project.rb

@@ -291,6 +291,8 @@ class Project < ActiveRecord::Base
   delegate :add_guest, :add_reporter, :add_developer, :add_maintainer, :add_role, to: :team
   delegate :add_master, to: :team # @deprecated
   delegate :group_runners_enabled, :group_runners_enabled=, :group_runners_enabled?, to: :ci_cd_settings
+  delegate :group_clusters_enabled?, to: :group, allow_nil: true
+  delegate :root_ancestor, to: :namespace, allow_nil: true
   # Validations
   validates :creator, presence: true, on: :create

spec/models/concerns/deployment_platform_spec.rb

@@ -69,8 +69,6 @@ describe DeploymentPlatform do
       let(:group) { group_cluster.group }
       before do
-        stub_feature_flags(deploy_group_clusters: true)
-
         project.update!(group: group)
       end
@@ -118,7 +116,7 @@ describe DeploymentPlatform do
       context 'feature flag disabled' do
         before do
-          stub_feature_flags(deploy_group_clusters: false)
+          stub_feature_flags(group_clusters: false)
         end
         it 'returns nil' do

spec/models/group_spec.rb

@@ -745,4 +745,33 @@ describe Group do
       let(:uploader_class) { AttachmentUploader }
     end
   end
+
+  describe '#group_clusters_enabled?' do
+    before do
+      # Override global stub in spec/spec_helper.rb
+      expect(Feature).to receive(:enabled?).and_call_original
+    end
+
+    subject { group.group_clusters_enabled? }
+
+    it { is_expected.to be_truthy }
+
+    context 'explicitly disabled for root ancestor' do
+      before do
+        feature = Feature.get(:group_clusters)
+        feature.disable(group.root_ancestor)
+      end
+
+      it { is_expected.to be_falsey }
+    end
+
+    context 'explicitly disabled for root ancestor' do
+      before do
+        feature = Feature.get(:group_clusters)
+        feature.enable(group.root_ancestor)
+      end
+
+      it { is_expected.to be_truthy }
+    end
+  end
 end

spec/models/namespace_spec.rb

@@ -721,6 +721,7 @@ describe Namespace do
       deep_nested_group = create(:group, parent: nested_group)
       very_deep_nested_group = create(:group, parent: deep_nested_group)
+      expect(root_group.root_ancestor).to eq(root_group)
       expect(nested_group.root_ancestor).to eq(root_group)
       expect(deep_nested_group.root_ancestor).to eq(root_group)
       expect(very_deep_nested_group.root_ancestor).to eq(root_group)

spec/models/project_spec.rb

@@ -412,6 +412,8 @@ describe Project do
     it { is_expected.to delegate_method(:members).to(:team).with_prefix(true) }
     it { is_expected.to delegate_method(:name).to(:owner).with_prefix(true).with_arguments(allow_nil: true) }
+    it { is_expected.to delegate_method(:group_clusters_enabled?).to(:group).with_arguments(allow_nil: true) }
+    it { is_expected.to delegate_method(:root_ancestor).to(:namespace).with_arguments(allow_nil: true) }
   end
   describe '#to_reference_with_postfix' do
@@ -2129,6 +2131,29 @@ describe Project do
     end
   end
+  describe '#root_ancestor' do
+    let(:project) { create(:project) }
+
+    subject { project.root_ancestor }
+
+    it { is_expected.to eq(project.namespace) }
+
+    context 'in a group' do
+      let(:group) { create(:group) }
+      let(:project) { create(:project, group: group) }
+
+      it { is_expected.to eq(group) }
+    end
+
+    context 'in a nested group', :nested_groups do
+      let(:root) { create(:group) }
+      let(:child) { create(:group, parent: root) }
+      let(:project) { create(:project, group: child) }
+
+      it { is_expected.to eq(root) }
+    end
+  end
+
   describe '#lfs_enabled?' do
     let(:project) { create(:project) }