A python script to fairly quickly delete a large S3 bucket (though Lifecycle policies may be the only option for extremely large buckets)

large-bucket-s3-delete.py

import boto3
from concurrent.futures import ThreadPoolExecutor

client1 = boto3.client(
    'sts',
    aws_session_token='my-current-session-token' # EDIT HERE
    )

response = client1.get_caller_identity(
)

sts_assumed_role = client1.assume_role(
    RoleArn='arn:aws:iam::123456789101:role/my-role', # EDIT HERE
    RoleSessionName='mysession'
)

credentials=sts_assumed_role['Credentials']

print(credentials["SessionToken"])
client=boto3.client(
    's3',
    aws_access_key_id=credentials['AccessKeyId'],
    aws_secret_access_key=credentials['SecretAccessKey'],
    aws_session_token=credentials['SessionToken'],
)

bucketname = 'my-bucket-name-without-s3-protocol' # EDIT HERE
# i.e. "my-bucket" not "s3://my-bucket"

def deleteobjects(key, versionid):
    client.delete_object(Bucket=bucketname, Key=key, VersionId=versionid)
    print('Deleting delete marker {0} for version {1}'.format(key, versionid))
    
#We will need to gather a list of all versions by using the paginator for the list_object_versions call
paginator = client.get_paginator('list_object_versions')
pages = paginator.paginate(Bucket=bucketname)
for page in pages:
    listofobjects = page.get('Versions')
    listofdeletemarkers = page.get('DeleteMarkers')
    if listofobjects != None:
        with ThreadPoolExecutor(max_workers=20) as executor:
            for objectL in listofobjects:
                executor.submit(deleteobjects, key=objectL['Key'], versionid=objectL['VersionId'])
    elif listofdeletemarkers != None:
        with ThreadPoolExecutor(max_workers=20) as executor:
            for deletemarker in listofdeletemarkers:
                executor.submit(deleteobjects, key=deletemarker['Key'], versionid=deletemarker['VersionId'])
                    
print('Deletion of objects complete!')

response = client.delete_bucket(Bucket=bucketname)