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

1 files changed, 19 insertions, 0 deletions

diff --git a/spec/workers/group_destroy_worker_spec.rb b/spec/workers/group_destroy_worker_spec.rb
new file mode 100644
index 00000000000..4e4eaf9b2f7
--- /dev/null
+++ b/spec/workers/group_destroy_worker_spec.rb
@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe GroupDestroyWorker do
+  let(:group) { create(:group) }
+  let(:user) { create(:admin) }
+  let!(:project) { create(:project, namespace: group) }
+
+  subject { GroupDestroyWorker.new }
+
+  describe "#perform" do
+    it "deletes the project" do
+      subject.perform(group.id, user.id)
+
+      expect(Group.all).not_to include(group)
+      expect(Project.all).not_to include(project)
+      expect(Dir.exist?(project.path)).to be_falsey
+    end
+  end
+end