How reliable is AWS S3 Event Nofications on SQS?

Question

I want to design an application that is based on AWS S3 Event Notifications mechanism. Basically each time a file is placed into a S3 bucket, then an SQS notification is triggered.

The official documentation says pretty clearly that "On very rare occasions, events might be lost ."

Does anyone knows what this "rare occasions" means? Would it be safer to send the SQS notification manually (the sender adds the file into the bucket and then sends the SQS notification) instead of relying on this Event Notification System?

Thanks!

Answer 1

"On very rare occasions, events might be lost."

Basically refers to outages to one of the following:

• S3
• SQS
• Network Connectivity issues
• General Problems in the Availability zone
• General Problems in the Region

Most of these things will remain an issue, even if you send the notifications manually.

Answer 2

AWS documentation also says the following (in https://docs.aws.amazon.com/AmazonS3/latest/userguide/NotificationHowTo.html#supported-notification-event-types ): Amazon S3 event notifications are designed to be delivered at least once. Typically, event notifications are delivered in seconds but can sometimes take a minute or longer. If two writes are made to a single non-versioned object at the same time, it is possible that only a single event notification will be sent. If you want to ensure that an event notification is sent for every successful write, you can enable versioning on your bucket. With versioning, every successful write will create a new version of your object and will also send an event notification.