Resolve cross-db queries for Runner scopes

The changes are behind the FF ci_find_runners_by_ci_mirrors

app/models/ci/runner.rb

@@ -112,6 +112,13 @@ module Ci
       from("(#{union_sql}) #{table_name}")
     }
 
+    scope :belonging_to_group_and_ancestors, -> (group_id) {
+      group_self_and_ancestors_ids = ::Group.find_by(id: group_id)&.self_and_ancestor_ids
+
+      joins(:runner_namespaces)
+        .where(ci_runner_namespaces: { namespace_id: group_self_and_ancestors_ids })
+    }
+
     # deprecated
     # split this into: belonging_to_group & belonging_to_group_and_ancestors
     scope :legacy_belonging_to_group, -> (group_id, include_ancestors: false) {

ee/lib/analytics/devops_adoption/snapshot_calculator.rb

@@ -61,8 +61,12 @@ module Analytics
       # rubocop: enable CodeReuse/ActiveRecord
 
       def runner_configured
-        ::Gitlab::Database.allow_cross_joins_across_databases(url: 'https://gitlab.com/gitlab-org/gitlab/-/issues/337541') do
-          Ci::Runner.active.legacy_belonging_to_group_or_project(snapshot_groups, snapshot_project_ids).exists?
+        if ::Feature.enabled?(:ci_find_runners_by_ci_mirrors, enabled_namespace.namespace, default_enabled: :yaml)
+          Ci::Runner.active.belonging_to_group_or_project_descendants(enabled_namespace.namespace.id).exists?
+        else
+          ::Gitlab::Database.allow_cross_joins_across_databases(url: 'https://gitlab.com/gitlab-org/gitlab/-/issues/337541') do
+            Ci::Runner.active.legacy_belonging_to_group_or_project(snapshot_groups, snapshot_project_ids).exists?
+          end
         end
       end
 

ee/spec/lib/analytics/devops_adoption/snapshot_calculator_spec.rb

@@ -61,7 +61,7 @@ RSpec.describe Analytics::DevopsAdoption::SnapshotCalculator do
     it { is_expected.to eq false }
   end
 
-  describe 'runner_configured' do
+  shared_examples 'runner_configured' do
     subject { data[:runner_configured] }
 
     let!(:inactive_runner) { create(:ci_runner, :project, active: false) }
@@ -77,6 +77,16 @@ RSpec.describe Analytics::DevopsAdoption::SnapshotCalculator do
     it { is_expected.to eq false }
   end
 
+  it_behaves_like 'runner_configured'
+
+  context 'when the FF ci_find_runners_by_ci_mirrors is disabled' do
+    before do
+      stub_feature_flags(ci_find_runners_by_ci_mirrors: false)
+    end
+
+    it_behaves_like 'runner_configured'
+  end
+
   describe 'pipeline_succeeded' do
     subject { data[:pipeline_succeeded] }
 

lib/api/ci/runners.rb

@@ -229,7 +229,12 @@ module API
           use :pagination
         end
         get ':id/runners' do
-          runners = ::Ci::Runner.legacy_belonging_to_group(user_group.id, include_ancestors: true)
+          runners = if ::Feature.enabled?(:ci_find_runners_by_ci_mirrors, user_group, default_enabled: :yaml)
+                      ::Ci::Runner.belonging_to_group_and_ancestors(user_group.id)
+                    else
+                      ::Ci::Runner.legacy_belonging_to_group(user_group.id, include_ancestors: true)
+                    end
+
           runners = apply_filter(runners, params)
 
           present paginate(runners), with: Entities::Ci::Runner

spec/models/ci/runner_spec.rb

@@ -1438,6 +1438,16 @@ RSpec.describe Ci::Runner do
     end
   end
 
+  describe '.belonging_to_group_and_ancestors' do
+    let_it_be(:parent_group) { create(:group) }
+    let_it_be(:parent_runner) { create(:ci_runner, :group, groups: [parent_group]) }
+    let_it_be(:group) { create(:group, parent: parent_group) }
+
+    it 'returns the group runner from the parent group' do
+      expect(described_class.belonging_to_group_and_ancestors(group.id)).to contain_exactly(parent_runner)
+    end
+  end
+
   describe '.belonging_to_group_or_project_descendants' do
     it 'returns the specific group runners' do
       group1 = create(:group)

spec/requests/api/ci/runners_spec.rb

@@ -980,7 +980,7 @@ RSpec.describe API::Ci::Runners do
     end
   end
 
-  describe 'GET /groups/:id/runners' do
+  shared_context 'GET /groups/:id/runners' do
     context 'authorized user with maintainer privileges' do
       it 'returns all runners' do
         get api("/groups/#{group.id}/runners", user)
@@ -1048,6 +1048,16 @@ RSpec.describe API::Ci::Runners do
     end
   end
 
+  it_behaves_like 'GET /groups/:id/runners'
+
+  context 'when the FF ci_find_runners_by_ci_mirrors is disabled' do
+    before do
+      stub_feature_flags(ci_find_runners_by_ci_mirrors: false)
+    end
+
+    it_behaves_like 'GET /groups/:id/runners'
+  end
+
   describe 'POST /projects/:id/runners' do
     context 'authorized user' do
       let_it_be(:project_runner2) { create(:ci_runner, :project, projects: [project2]) }