Appendix F. S3 event message structure

This appendix covers

• S3 event message structure

If you use S3 with Lambda, you need to understand the S3 event message structure for the purpose of extracting needed information from the message. This appendix describes the structure of the event message, so that you’re aware of the available properties and their expected values.

F.1. S3 structure

The following listing shows an example S3 event message after an object has been added to a bucket. This example is adapted from https://docs.aws.amazon.com/AmazonS3/latest/dev/notification-content-structure.html.

Listing F.1. S3 Event message structure

F.2. A few things to remember

• The key of the object is encoded. For example, the file hello world.jpg is encoded to hello+world.jpg.
• Event notifications are not guaranteed to arrive in order, but you can use the sequencer to determine which event came later (a greater hex value indicates that the sequence came later).