Is it possible to enable CRR between two buckets in different accounts and different regions?

Question

I work for a company and we have a goverment client who wants to use CRR between their bucket and ours. Our bucket is in a different gov region than theirs (we are us-gov-east and they are us-gov-west). Also, we have different AWS accounts. The biggest concern the client has is the data traversing the public internet even if it is encrypted. They would like to know if we can implement a solution to have the CRR happen strictly through the AWS Private Network. Now I have done things in the past like set up an EC2 instance to grab data from S3 through way of a GW endpoint so I know that's possible. But is CRR between two different buckets in two different regions and accounts possible without traversing through the public internet?

Or is this already the case whenever two buckets try and use CRR? Do they go strictly through the AWS Backbone and not the public internet? If this is true, then this verification alone would be enough proof that we can assure the client the data will not traverse the public internet.

Also if this is not possible, can someone please provide me alternatives? The goal is to have object replication without using the public internet.

Or is this already the case whenever two buckets try and use CRR? Do they go strictly through the AWS Backbone and not the public internet? If this is true, then this verification alone would be enough proof that we can assure the client the data will not traverse the public internet.

Also if this is not possible, can someone please provide me alternatives? The goal is to have object replication without using the public internet.

Mike · Answer

Yes, it is possible to enable Cross-Region Replication (CRR) between two Amazon S3 buckets that are in different AWS accounts and different regions. This is a common use case for organizations that want to maintain data redundancy, comply with data sovereignty requirements, or optimize access to data across different geographical locations. [1]

To set up CRR between buckets in different accounts and regions, you'll need to follow these general steps:

1. Ensure both buckets have versioning enabled.
2. Create an IAM role in the source account that allows S3 to assume the role and perform replication.
3. Set up a bucket policy on the destination bucket that allows the source bucket to replicate objects.
4. Configure the replication rule on the source bucket, specifying the destination bucket in the other account and region.

Here's a high-level example of how you might set up the replication rule using the AWS CLI:

aws s3api put-bucket-replication --bucket source-bucket --replication-configuration file://replication.json

The replication.json file might look something like this:

{
  "Role": "arn:aws:iam::source-account-id:role/replication-role",
  "Rules": [
    {
      "Status": "Enabled",
      "Priority": 1,
      "DeleteMarkerReplication": { "Status": "Disabled" },
      "Filter": {},
      "Destination": {
        "Bucket": "",
        "Account": "destination-account-id"
      }
    }
  ]
}

Remember to replace source-account-id, destination-account-id, source-bucket, and destination-bucket with your actual account IDs and bucket names.

Some important considerations for cross-account, cross-region replication:

1. The IAM role in the source account must have permissions to read from the source bucket and replicate to the destination bucket.
2. The destination bucket must have a bucket policy that allows the source bucket to replicate objects into it.
3. You may need to consider the potential data transfer costs associated with cross-region replication.
4. Replication is not retroactive. Only new or updated objects will be replicated after you enable CRR.
5. You should ensure that both the source and destination regions are enabled for your AWS accounts.

By setting up CRR between buckets in different accounts and regions, you can create a robust data replication strategy that spans multiple AWS accounts and geographical locations, enhancing your data resilience and availability.

When using Cross-Region Replication (CRR) between S3 buckets in different regions, the data does indeed travel through Amazon's private network infrastructure, not over the public internet. However, it's important to understand some nuances:

1. AWS Global Network: AWS uses its own global network infrastructure to transfer data between regions. This network is designed to be secure, reliable, and high-performance. [2]
2. Data Encryption: By default, Amazon S3 uses SSL/TLS to encrypt data in transit between regions. This adds an extra layer of security even though the data is already traveling on AWS's private network.
3. Inter-Region Data Transfer: While the data travels on AWS's private network, it's important to note that it does leave the geographical boundaries of the source region. This could be relevant for compliance or data sovereignty requirements.
4. No VPC Involvement: The replication traffic does not go through your VPCs or require any specific VPC configuration. It's handled entirely by AWS at the S3 service level.
5. Data Transfer Costs: Even though the data travels on AWS's private network, there are still data transfer costs associated with moving data between regions. [3]
6. Consistency: While the network is private and optimized, replication is still asynchronous and eventually consistent. The time it takes for an object to replicate depends on the size of the object and the distance between regions.
7. S3 Transfer Acceleration: If you're concerned about transfer speeds, you might consider using S3 Transfer Acceleration for the initial data upload to S3, though this isn't directly related to the replication process itself.

While the AWS private network provides a secure path for your data, if you have extremely sensitive data or stringent compliance requirements, you might want to consider additional measures:

1. Using server-side encryption with AWS KMS for objects in both the source and destination buckets.
2. Enabling S3 Object Lock on the destination bucket to prevent accidental or malicious deletions.
3. Setting up AWS CloudTrail to monitor and log all S3 API activities in both regions.

In summary, while CRR data does travel on AWS's private network infrastructure, it's important to understand the implications for your specific use case, especially regarding data sovereignty, compliance, and security requirements.

Sources:
[1] Ten tips for multi-tenant, multi-Region object replication in Amazon S3 https://aws.amazon.com/blogs/storage/ten-tips-for-multi-tenant-multi-region-object-replication-in-amazon-s3/
[2] Private network for enterprises: AWS Private 5G https://community.aws/content/2aysRkJj9E41gnNRqJdaIB3czeo/private-network-for-enterprises-aws-private-5g
[3] What is AWS Private 5G? https://docs.aws.amazon.com/private-networks/latest/userguide/what-is-private-5g.html

Is it possible to enable CRR between two buckets in different accounts and different regions?

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