Question

How do you make an AWS S3 public folder private again?

I was testing out some staging data, so I made the entire folder public within a bucket. I’d like to restrict its access again. So how do I make the folder private again?

Answer 1

From what I understand, the ‘Make public’ option in the managment console recursively adds a public grant for every object ‘in’ the directory.
You can see this by right-clicking on one file, then click on ‘Properties’. You then need to click on ‘Permissions’ and there should be a line:

 Grantee:  Everyone  [x] open/download  [] view permissions   [] edit permission.

If you upload a new file within this directory it won’t have this public access set and therefore be private.

You need to remove public read permission one by one, either manually if you only have a few keys or by using a script.

I wrote a small script in Python with the ‘boto’ module to recursively remove the ‘public read’ attribute of all keys in a S3 folder:

#!/usr/bin/env python
#remove public read right for all keys within a directory

#usage: remove_public.py bucketName folderName

import sys
import boto3

BUCKET = sys.argv[1]
PATH = sys.argv[2]
s3client = boto3.client("s3")
paginator = s3client.get_paginator('list_objects_v2')
page_iterator = paginator.paginate(Bucket=BUCKET, Prefix=PATH)
for page in page_iterator:
    keys = page['Contents']
    for k in keys:
        response = s3client.put_object_acl(
                        ACL='private',
                        Bucket=BUCKET,
                        Key=k['Key']
                    )

I tested it in a folder with (only) 2 objects and it worked. If you have lots of keys it may take some time to complete and a parallel approach might be necessary.