AWS 使用 Lambda 將文件從 S3 存儲桶下載到 Windows 本地目錄

Question

我想使用 Lambda 函數將文件從 S3 存儲桶下載到我的 Windows PC 上的本地目錄。

我試過這個名為“myLambdaFunction”的代碼：

import boto3
import os

def lambda_handler(event, context):   
    ACCESS_KEY = 'AAA...'
    SECRET_KEY = 'BBB...'

path = os.path.join("C:", "Users", "username", "Downloads")
if not os.path.exists(path):
    os.makedirs(path)
s3 = boto3.client('s3', aws_access_key_id=ACCESS_KEY , aws_secret_access_key=SECRET_KEY)
s3.download_file('bucketName','1.mat',path)

# TODO implement
return {
    'statusCode': 200,
    'body': json.dumps('Hello from Lambda!')
}

當我從 Windows PC 運行以下命令時：

aws lambda invoke --function-name myLambdaFunction response.json

我收到以下錯誤消息：

{"errorMessage": "[Errno 30] Read-only file system: 'C:'", "errorType": "OSError", "stackTrace": ["  File \"/var/task/lambda_function.py\", line 37, in lambda_handler\n    os.makedirs(path)\n", "  File \"/var/lang/lib/python3.8/os.py\", line 211, in makedirs\n    makedirs(head, exist_ok=exist_ok)\n", "  File \"/var/lang/lib/python3.8/os.py\", line 211, in makedirs\n    makedirs(head, exist_ok=exist_ok)\n", "  File \"/var/lang/lib/python3.8/os.py\", line 211, in makedirs\n    makedirs(head, exist_ok=exist_ok)\n", "  File \"/var/lang/lib/python3.8/os.py\", line 221, in makedirs\n    mkdir(name, mode)\n"]}

當我從代碼中刪除路徑檢查時，出現以下錯誤：

{"errorMessage": "[Errno 2] No such file or directory: 'C:/Users/username/Downloads.dce48B09'", "errorType": "FileNotFoundError", "stackTrace": ["  File \"/var/task/lambda_function.py\", line 39, in lambda_handler\n    s3.download_file('bucketName','1.mat',path)\n", "  File \"/var/runtime/boto3/s3/inject.py\", line 170, in download_file\n    return transfer.download_file(\n", "  File \"/var/runtime/boto3/s3/transfer.py\", line 307, in download_file\n    future.result()\n", "  File \"/var/runtime/s3transfer/futures.py\", line 106, in result\n    return self._coordinator.result()\n", "  File \"/var/runtime/s3transfer/futures.py\", line 265, in result\n    raise self._exception\n", "  File \"/var/runtime/s3transfer/tasks.py\", line 126, in __call__\n    return self._execute_main(kwargs)\n", "  File \"/var/runtime/s3transfer/tasks.py\", line 150, in _execute_main\n    return_value = self._main(**kwargs)\n", "  File \"/var/runtime/s3transfer/download.py\", line 573, in _main\n    fileobj.seek(offset)\n", "  File \"/var/runtime/s3transfer/utils.py\", line 361, in seek\n    self._open_if_needed()\n", "  File \"/var/runtime/s3transfer/utils.py\", line 344, in _open_if_needed\n    self._fileobj = self._open_function(self._filename, self._mode)\n", "  File \"/var/runtime/s3transfer/utils.py\", line 259, in open\n    return open(filename, mode)\n"]}

不知何故，路徑與.dce48B09連接在一起，我不明白為什么。

我知道我可以使用命令

aws s3 cp ...

為了復制文件，雖然我需要添加更多的邏輯，而且使用 Lambda 會更方便。

Answer 1

Lambda 函數未在您的本地計算機上運行。 當您運行aws lambda invoke您正在觸發 AWS 在某個 AWS 服務器上運行您的 Lambda 函數實例。 lambda 函數將無法訪問您的本地計算機。

如果要在本地計算機上運行一些 Python 代碼以從 S3 下載文件，則需要將其編寫為常規 Python 腳本，而不是 Lambda 函數。