使用 lambda 从外部 s3 存储桶下载文件

Question

I want to use lambda to download backup files from external s3 account. I have got Access Key ID, Secret Access Key, Bucket Name and Region Name. And then synchronize it with my private s3 bucket. Is it possible? And how?

Answer 1

It appears your requirement is:

• Take data stored in Bucket-A in Account-A
• Copy it to Bucket-B in Account-B

The simplest way to do this is to use the CopyObject() command because it can directly transfer data between buckets (even between regions!) without needing to download & upload.

To do this, you will require one set of credentials that have Read permissions on Bucket-A and write permissions on Bucket-B . This can be either:

• An IAM User-A in Account-A that can read Bucket-A and a Bucket Policy on Bucket-B that permits User-A to write to Bucket-B , OR
• An IAM User-B in Account-B that can write to Bucket-B and a Bucket Policy on Bucket-A that permits Read access for User-B

Using the Bucket Policy means that one set of credentials can use the CopyObject() command to both Read & Write. Without that, you'd need to use one set of credentials to download an object and another set of credentials to upload the object. That's not a smart way to do it.

See: Provide Cross-Account Access to Objects In S3 Buckets

The easiest way to run the copy command is to use the AWS Command-Line Interface (CLI) aws s3 cp or aws s3 sync commands. In your case, if you wish to synchronize the contents of files, you would use aws s3 sync .

A final option is to use Cross-Region Replication - Amazon Simple Storage Service , but that only works on buckets in different regions. The buckets can belong to different AWS accounts.