Bucket Versioning

By default, S3 does not store multiple versions of an object. If you upload a file to a key that already contains an object, the old object is overwritten.

Bucket versioning is an optional feature where the bucket stores multiple versions of an object. It helps:

Prevent accidental deletion
Rollback to previous versions of files
Store multiple versions of files in the same key

On that last point, I recommend primarily using object versions for "just-in-case" purposes, not for expected day-to-day versioning. If you have an application that stores multiple versions of the "same" object, I would probably store them in different keys entirely. If I write a bug, I don't want to screw up my "user's versions"... I prefer my infrastructure-level backups to only be used for disaster recovery.

Assignment

Enable versioning on your public bucket.
Make a copy of boots-image-horizontal.png locally called bootsimg.png.
Upload bootsimg.png to the root of your public bucket.
Open the image in the browser using its public URL - confirm that it's the horizontal image.
Delete the local bootsimg.png file, and now make a copy of boots-image-vertical.png locally called bootsimg.png.
Upload bootsimg.png to the root of your public bucket. You should see that it doesn't create a new object. Instead, click on the bootsimg.png object and go to the "Versions" tab - you should see two versions!
Open the image in the browser using its public URL - confirm that it's the vertical image now (you might need to hard refresh and clear the cache).
Run the following to list the versions of the object:

aws s3api list-object-versions --bucket BUCKET --prefix bootsimg.png --no-cli-pager

Replace BUCKET with your bucket name.

Run it again, but redirect the output to a file:

aws s3api list-object-versions --bucket BUCKET --prefix bootsimg.png --no-cli-pager > /tmp/versions.json

Run and submit the CLI tests.

If you're interested, go delete the latest version using the web console. You should be able to see the old version again when visiting the public URL! Very handy for rolling back changes.