Main part of S3 lowercaser

lowercaser.py

def lambda_handler(event, context):
    for record in event['Records']:
        try:
            bucket_name = record['s3']['bucket']['name']
            object_name = record['s3']['object']['key']
            object_size = record['s3']['object']['size']
            version_id = record['s3']['object']['versionId']

            # Key's come HTML encoded, we need to remove that. 
            object_name = urllib.parse.unquote_plus(object_name)
            lower_case_object_name = object_name.lower()
            if lower_case_object_name != object_name:
                print("Current object is not of the correct case (" + bucket_name + " / " + object_name +")")

                # If over ~ 5 GB copy with alternative method
                if object_size > 5368709100:
                    copy_large_object(bucket_name, object_name, lower_case_object_name)
                else:
                    copy_object(bucket_name, object_name, lower_case_object_name)
                delete_object_entirely(object_name, version_id, bucket_name)
            else:
                print("Already in the right case: (" + bucket_name + " / " + lower_case_object_name +")")
        except Exception as e:
            send_failed_object(record, e)
            raise
        
    return