Fix bug where destroying a namespace would not always destroy projects

There is a race condition in DestroyGroupService now that projects are deleted asynchronously:

1. User attempts to delete group
2. DestroyGroupService iterates through all projects and schedules a Sidekiq job to delete each Project
3. DestroyGroupService destroys the Group, leaving all its projects without a namespace
4. Projects::DestroyService runs later but the can?(current_user,
   :remove_project) is `false` because the user no longer has permission to
   destroy projects with no namespace.
5. This leaves the project in pending_delete state with no namespace/group.

Projects without a namespace or group also adds another problem: it's not possible to destroy the container
registry tags, since container_registry_path_with_namespace is the wrong value.

The fix is to destroy the group asynchronously and to run execute directly on Projects::DestroyService.

Closes #17893

2 files changed, 53 insertions, 0 deletions

diff --git a/spec/controllers/admin/groups_controller_spec.rb b/spec/controllers/admin/groups_controller_spec.rb
new file mode 100644
index 00000000000..0239aea47fb
--- /dev/null
+++ b/spec/controllers/admin/groups_controller_spec.rb
@@ -0,0 +1,24 @@
+require 'spec_helper'
+
+describe Admin::GroupsController do
+  let(:group) { create(:group) }
+  let(:project) { create(:project, namespace: group) }
+  let(:admin) { create(:admin) }
+
+  before do
+    sign_in(admin)
+    Sidekiq::Testing.fake!
+  end
+
+  describe 'DELETE #destroy' do
+    it 'schedules a group destroy' do
+      expect { delete :destroy, id: project.group.path }.to change(GroupDestroyWorker.jobs, :size).by(1)
+    end
+
+    it 'redirects to the admin group path' do
+      delete :destroy, id: project.group.path
+
+      expect(response).to redirect_to(admin_groups_path)
+    end
+  end
+end
diff --git a/spec/controllers/groups_controller_spec.rb b/spec/controllers/groups_controller_spec.rb
index cd98fecd0c7..4ae6364207b 100644
--- a/spec/controllers/groups_controller_spec.rb
+++ b/spec/controllers/groups_controller_spec.rb
@@ -75,4 +75,33 @@ describe GroupsController do
       end
     end
   end
+
+  describe 'DELETE #destroy' do
+    context 'as another user' do
+      it 'returns 404' do
+        sign_in(create(:user))
+
+        delete :destroy, id: group.path
+
+        expect(response.status).to eq(404)
+      end
+    end
+
+    context 'as the group owner' do
+      before do
+        Sidekiq::Testing.fake!
+        sign_in(user)
+      end
+
+      it 'schedules a group destroy' do
+        expect { delete :destroy, id: group.path }.to change(GroupDestroyWorker.jobs, :size).by(1)
+      end
+
+      it 'redirects to the root path' do
+        delete :destroy, id: group.path
+
+        expect(response).to redirect_to(root_path)
+      end
+    end
+  end
 end