support group hierarchies for group runners

app/models/ci/runner.rb

@@ -31,13 +31,10 @@ module Ci
       joins(:runner_projects).where(ci_runner_projects: { project_id: project_id })
     }
     scope :belonging_to_group, -> (project_id) {
-      joins(
-        %{
-          INNER JOIN ci_runner_groups ON ci_runner_groups.runner_id = ci_runners.id
-          INNER JOIN namespaces ON namespaces.id = ci_runner_groups.group_id
-          INNER JOIN projects ON projects.namespace_id = namespaces.id
-        }
-      ).where('projects.id = :project_id', project_id: project_id)
+      project_groups = ::Group.joins(:projects).where(projects: { id: project_id })
+      hierarchy_groups = Gitlab::GroupHierarchy.new(project_groups).base_and_ancestors
+
+      joins(:groups).where(namespaces: { id: hierarchy_groups })
     }
 
     scope :owned_or_shared, -> (project_id) do

spec/models/ci/runner_spec.rb

@@ -93,6 +93,15 @@ describe Ci::Runner do
 
       expect(described_class.belonging_to_group(specific_project.id)).to eq [specific_runner]
     end
+
+    it 'returns the group runner from a parent group' do
+      parent_group = create :group
+      group = create :group, parent: parent_group
+      project = create :project, group: group
+      runner = create :ci_runner, :specific, groups: [parent_group]
+
+      expect(described_class.belonging_to_group(project.id)).to eq [runner]
+    end
   end
 
   describe '.owned_or_shared' do