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File System Illusion

Remember how I mentioned that S3's "object storage" doesn't support directories? Well, that's true, but there's some trickery involved that makes it feel like it does.

Directories are really great for organizing stuff. Storing everything in one giant bucket makes a big hard-to-manage mess. So, S3 makes your objects feel like they're in directories, even though they're not.

It's Just Prefixes

Keys inside of a bucket are just strings. And strings can have slashes, right? Right.

If you upload an object to S3 with the key users/john/profile.jpg, we can kind of pretend that the object is in a directory called users and a subdirectory called john. Not only that, but the S3 API actually provides tools that allow this illusion to thrive.

Let's say I create some objects with keys:

users/dan/profile.jpg
users/dan/friends.jpg
users/lane/profile.jpg
users/lane/friends.jpg
people/matt/profile.jpg

Then I can use the S3 API to list all the objects with the key prefix users/lane. It returns:

users/lane/profile.jpg
users/lane/friends.jpg

or just everything with the prefix "users":

users/dan/profile.jpg
users/dan/friends.jpg
users/lane/profile.jpg
users/lane/friends.jpg

It feels like a hierarchy, without all the technical overhead of actually creating directories.

Assignment

Manually create a directory (folder) called "backups" in your bucket
Upload all the files from your samples directory there for safe keeping
Use the AWS CLI to list the files in each directory:

aws s3 ls s3://YOURBUCKET/backups/

Replace YOURBUCKET with the name of your bucket.

Do it again, but redirect the output to /tmp/s3_listing.txt:

aws s3 ls s3://YOURBUCKET/backups/ > /tmp/s3_listing.txt

Run and submit the CLI tests.

You can delete the backups folder and its contents when you're done.