Merge branch 'fix-namespace-deletion' into 'master'

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 run `execute` directly on Projects::DestroyService.
 
Closes #17893

See merge request !4341

2 files changed, 19 insertions, 4 deletions

diff --git a/app/services/delete_user_service.rb b/app/services/delete_user_service.rb
index 2f237de813c..eaff88d6463 100644
--- a/app/services/delete_user_service.rb
+++ b/app/services/delete_user_service.rb
@@ -21,6 +21,11 @@ class DeleteUserService
       ::Projects::DestroyService.new(project, current_user, skip_repo: true).async_execute
     end
 
-    user.destroy
+    # Destroy the namespace after destroying the user since certain methods may depend on the namespace existing
+    namespace = user.namespace
+    user_data = user.destroy
+    namespace.really_destroy!
+
+    user_data
   end
 end
diff --git a/app/services/destroy_group_service.rb b/app/services/destroy_group_service.rb
index a4ebccb5606..0081364b8aa 100644
--- a/app/services/destroy_group_service.rb
+++ b/app/services/destroy_group_service.rb
@@ -5,13 +5,23 @@ class DestroyGroupService
     @group, @current_user = group, user
   end
 
+  def async_execute
+    group.transaction do
+      # Soft delete via paranoia gem
+      group.destroy
+      job_id = GroupDestroyWorker.perform_async(group.id, current_user.id)
+      Rails.logger.info("User #{current_user.id} scheduled a deletion of group ID #{group.id} with job ID #{job_id}")
+    end
+  end
+
   def execute
     group.projects.each do |project|
+      # Execute the destruction of the models immediately to ensure atomic cleanup.
       # Skip repository removal because we remove directory with namespace
-      # that contain all this repositories
-      ::Projects::DestroyService.new(project, current_user, skip_repo: true).async_execute
+      # that contain all these repositories
+      ::Projects::DestroyService.new(project, current_user, skip_repo: true).execute
     end
 
-    group.destroy
+    group.really_destroy!
   end
 end