2014-10_AWS_buckets_migration.md

created_at	kind	publish	title	authors	tags
2014-10-21	article	true	Data migration between two Amazon S3 buckets on different accounts	tukan	amazon

Recently we needed to migrate data between two Amazon S3 buckets on different accounts. Situation seemed simple but while diving into topic we didn't find good documentation how to accomplish this. We tried few solutions but result one was that we had migrated data between buckets without proper rights on files so we couldn't do much with migrated data.

Solution is to add proper policies on destination bucket and use sync on source bucket via AWS CLI. Here's how we did it in 2 steps:

1. Create policy on destination bucket. Source bucket user needs to have access to destination bucket. You need to know source bucket account ID and source bucket user name (for user name you may use root if you don't want to use specific user).

{
  "Id": "Policy1357935677554",
    "Statement": 
      [
        {
          "Sid": "Stmt1357935647218",
          "Action": "s3:*",
          "Effect": "Allow",
          "Resource": 
            [
              "arn:aws:s3:::destination-bucket-here",
              "arn:aws:s3:::destination-bucket-here/*"
            ],
          "Principal": 
            {
              "AWS": "arn:aws:iam::account-number-here:user-name-here"
            }
        }
      ]
}

1. Synchronise buckets via AWS CLI Make sure you have AWS CLI installed and set up with source bucket user credentials. Then you're ready to use sync.

A sync command makes it easy to synchronise the contents of a local folder with a copy in a S3 bucket.

In our case we'll synchronise two S3 buckets on different accounts.

aws s3 sync s3://source-bucket-name s3://destination-bucket-name --acl public-read

In case you may need different parameters have a look at sync in AWS reference.