Only send one notification for failed remote mirror

Retries in Sidekiq and in the remote mirror scheduler can cause repeated
attempts in quick succession if the sync fails. Each failure will then
send an e-mail to all project maintainers, which can spam users
unnecessarily.

Modify the logic to send one notification the first time the mirror
fails by setting `error_notification_sent` to `true` and reset the
flag after a successful sync.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/56222

2 files changed, 46 insertions, 0 deletions

diff --git a/spec/workers/remote_mirror_notification_worker_spec.rb b/spec/workers/remote_mirror_notification_worker_spec.rb
new file mode 100644
index 00000000000..e3db10ed645
--- /dev/null
+++ b/spec/workers/remote_mirror_notification_worker_spec.rb
@@ -0,0 +1,39 @@
+require 'spec_helper'
+
+describe RemoteMirrorNotificationWorker, :mailer do
+  set(:project) { create(:project, :repository, :remote_mirror) }
+  set(:mirror) { project.remote_mirrors.first }
+
+  describe '#execute' do
+    it 'calls NotificationService#remote_mirror_update_failed when the mirror exists' do
+      mirror.update_column(:last_error, "There was a problem fetching")
+
+      expect(NotificationService).to receive_message_chain(:new, :remote_mirror_update_failed)
+
+      subject.perform(mirror.id)
+
+      expect(mirror.reload.error_notification_sent?).to be_truthy
+    end
+
+    it 'does nothing when the mirror has no errors' do
+      expect(NotificationService).not_to receive(:new)
+
+      subject.perform(mirror.id)
+    end
+
+    it 'does nothing when the mirror does not exist' do
+      expect(NotificationService).not_to receive(:new)
+
+      subject.perform(RemoteMirror.maximum(:id).to_i.succ)
+    end
+
+    it 'does nothing when a notification has already been sent' do
+      mirror.update_columns(last_error: "There was a problem fetching",
+                            error_notification_sent: true)
+
+      expect(NotificationService).not_to receive(:new)
+
+      subject.perform(mirror.id)
+    end
+  end
+end
diff --git a/spec/workers/repository_update_remote_mirror_worker_spec.rb b/spec/workers/repository_update_remote_mirror_worker_spec.rb
index d73b0b53713..b582a3650b6 100644
--- a/spec/workers/repository_update_remote_mirror_worker_spec.rb
+++ b/spec/workers/repository_update_remote_mirror_worker_spec.rb
@@ -22,6 +22,13 @@ describe RepositoryUpdateRemoteMirrorWorker do
         expect { subject.perform(remote_mirror.id, Time.now) }.to change { remote_mirror.reload.update_status }.to('finished')
       end
 
+      it 'resets the notification flag upon success' do
+        expect_any_instance_of(Projects::UpdateRemoteMirrorService).to receive(:execute).with(remote_mirror).and_return(status: :success)
+        remote_mirror.update_column(:error_notification_sent, true)
+
+        expect { subject.perform(remote_mirror.id, Time.now) }.to change { remote_mirror.reload.error_notification_sent }.to(false)
+      end
+
       it 'sets status as failed when update remote mirror service executes with errors' do
         error_message = 'fail!'