Moto: Alias Issue when Creating S3 Access Point is Fixed

 Two days ago, I discovered a small bug in the moto library that I use to unit test my lambdas on AWS. I needed to create an S3 Access Point with boto3, and while retrieving the its alias, I had different results when using the return value of create_access_point or get_access_point.

So I wrote a small unit test:

from moto import mock_s3control

import boto3

@mock_s3control

def test_access_point_alias():

    client = boto3.client("s3control")

    alias_from_create = client.create_access_point(

        AccountId="123456789012",

        Name="my-access-point",

        Bucket="MyBucket",

    )["Alias"]

    alias_from_get = client.get_access_point(

        AccountId="123456789012",

        Name="my-access-point",

    )["Alias"]

    assert alias_from_create == alias_from_get

I create an S3 Access Point, and retrieve its alias in two ways: from the response of the create_access_point function, and from the get_access_point function. On my moto 4.2.6, this test fails.

So I opened an issue on the project's repository. It was fixed and closed on the same day. That's reactivity!

AWS: Simpler S3 File Deletes by Prefix

 I came across this code that deletes files in an S3 from a list of prefixes:

s3_client = boto3.client('s3')

for prefix in prefix_list:

    paginator = s3_client.get_paginator('list_objects_v2')

    file_list = paginator.paginate(

        Bucket=data_bucket,

        Prefix=prefix

    )

    for current_content in file_list:

        for current_file in current_content.get('Contents', []):

            current_key = current_file['Key']

            response = s3_client.delete_object(

                Bucket=data_bucket,

                Key=current_key

            )

The code creates an S3 client, and then, for each prefix in a list, it creates a paginator. Paginators are great because they help you avoid using all your memory when the list of files is big. Using this paginator, the code retrieves the list of all the files corresponding to the prefix, and deletes it.

Nothing bad in the code, it works nicely. My only remark here, is that there exists a simpler way. Instead of using the S3 client, you can create an S3 bucket resource. From there, you can simply delete all files listed under a prefix using a simple filter:

s3_resource = boto3.resource('s3')

bucket = s3_resource.Bucket(data_bucket)

for prefix in prefix_list:

    bucket.objects.filter(Prefix=prefix).delete()

Simpler!