Persistent notifications

Persistent notifications enable reliable and asynchronous delivery of notifications from the Ceph Object Gateway to the endpoint configured at the topic.

Regular notifications are also reliable because the delivery to the endpoint is performed synchronously during the request. With persistent notifications, the Ceph Object Gateway retries sending notifications even when the endpoint is down or there are network issues during the operations, that is notifications are retried if not successfully delivered to the endpoint. Notifications are sent only after all other actions related to the notified operation are successful. If an endpoint goes down for a longer duration, the notification queue fills up and the S3 operations that have configured notifications for these endpoints will fail.