AWS S3バケットの指定フォルダ直下のフォルダとファイルをLambdaで取得する

import json
import boto3

def lambda_handler(event, context):
    S3Bucket = "{your-bucket-name}"
    S3KeyPrefix = ""
    dirDepth = 1

    folders = []
    files = []
    result = ""

    # Get requesting path from query string and normalize it.
    try:
        path = event['queryStringParameters']['path']
        if path is not None:
            S3KeyPrefix = path
            if (len(S3KeyPrefix) > 0) and (S3KeyPrefix[0] == "/"):
                S3KeyPrefix = S3KeyPrefix[1:]
            if (len(S3KeyPrefix) > 0) and (S3KeyPrefix[-1] == "/"):
                S3KeyPrefix = S3KeyPrefix[:-1]
            if (len(S3KeyPrefix) > 0):
                dirDepth = len(S3KeyPrefix.split('/')) + 1
    except Exception as e:
        print(e)

    # Create instances.
    s3 = boto3.resource('s3')
    bucket = s3.Bucket(S3Bucket)
    objs = bucket.meta.client.list_objects(Bucket = bucket.name, Prefix = S3KeyPrefix, Delimiter = "/")

    try:
        # Enumrate subfolders.
        for o in objs.get('CommonPrefixes'):
            folder = o.get('Prefix')
            folders.append(folder)
            subFolders = bucket.meta.client.list_objects(Bucket = bucket.name, Prefix = folder, Delimiter = "/")
            if (subFolders is not None) and (subFolders.get('CommonPrefixes') is not None):
                for f in subFolders.get('CommonPrefixes'):
                    subFolder = f.get('Prefix')
                    if len(subFolder.split('/')) == dirDepth + 1:
                        folders.append(subFolder)

        # Enumrate files.
        oFiles = bucket.meta.client.list_objects_v2(Bucket = bucket.name, Prefix = S3KeyPrefix)

        for f in oFiles.get('Contents'):
            file = f.get('Key')
            if (file[-1] != '/') and (len(file.split('/')) <= dirDepth):
                files.append(file)
    except Exception as e:
        result += "No such folder : " + S3KeyPrefix

    # Get results.
    folders = sorted(folders)
    result += "\n".join(folders) + "\n"
    files = sorted(files)
    result += "\n".join(files) + "\n"

    return {
        'statusCode': 200,
        'body': result
    }

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "ListObjectsInBucket",
            "Effect": "Allow",
            "Action": [
                "s3:ListBucket"
            ],
            "Resource": [
                "arn:aws:s3:::your-bucket-name"
            ]
        },
        {
            "Sid": "AllObjectActions",
            "Effect": "Allow",
            "Action": "s3:*Object",
            "Resource": [
                "arn:aws:s3:::your-bucket-name/*"
            ]
        }
    ]
}

{
  "queryStringParameters": {
    "path": "path-to-folders"
  }
}