Can't Get Amazon S3 Cross Region Replication Between Two Accounts to Work? Here's How

Can’t Get Amazon S3 Cross Region Replication Between Two Accounts to Work? Here’s How

Amazon S3 Cross Region Replication (CRR) is a powerful feature that enables automatic, asynchronous copying of objects across buckets in different AWS regions. It can be incredibly useful for disaster recovery, data migration, and compliance needs. But what happens when you’re trying to set up CRR between two different AWS accounts and it just doesn’t seem to work? In this blog post, we’ll explain why this might be happening and how to resolve the issue.

Understand the Basic Requirements

Before we delve into the solution, let’s clarify some basic prerequisites for setting up CRR:

1. Both source and destination buckets must have versioning enabled.
2. The AWS Identity and Access Management (IAM) roles must have the necessary permissions to replicate objects.
3. The AWS regions of the source and destination buckets must be different.

Assuming you’ve met these requirements, let’s move on to the common pitfalls and their solutions.

The Common Pitfalls and Solutions

1. Incorrect Bucket Policy

First, check your bucket policy. To replicate objects between AWS accounts, the destination bucket owner must grant the source bucket owner the necessary permissions.

Here’s a sample bucket policy for the destination bucket:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "DelegateS3Access",
            "Effect": "Allow",
            "Principal": {"AWS": "arn:aws:iam::Source_Account_ID:root"},
            "Action": ["s3:ReplicateObject", "s3:ReplicateDelete"],
            "Resource": [
                "arn:aws:s3:::Destination_Bucket_Name/*",
                "arn:aws:s3:::Destination_Bucket_Name"
            ]
        }
    ]
}

Replace Source_Account_ID with your source account ID and Destination_Bucket_Name with the name of your destination bucket.

2. Incorrect IAM Role Permissions

Next, verify the IAM role permissions. The IAM role associated with the source bucket must have permissions to replicate objects.

Here’s a sample IAM policy for the source bucket:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "s3:ReplicateObject",
                "s3:ReplicateDelete",
                "s3:GetBucketVersioning",
                "s3:GetObjectVersion"
            ],
            "Resource": "*"
        }
    ]
}

3. Incorrect Configuration of CRR

Lastly, ensure that the CRR is correctly set up. The source bucket must have a replication configuration that identifies the destination bucket and IAM role.

Here’s a sample replication configuration:

{
    "Rules": [
        {
            "Status": "Enabled",
            "Priority": 1,
            "DeleteMarkerReplication": { "Status": "Enabled" },
            "Filter": { "Prefix": "" },
            "Destination": {
                "Bucket": "arn:aws:s3:::Destination_Bucket_Name",
                "StorageClass": "STANDARD",
                "Account": "Destination_Account_ID"
            }
        }
    ],
    "Role": "arn:aws:iam::Source_Account_ID:role/Role_Name"
}

Replace Destination_Bucket_Name with the name of your destination bucket, Destination_Account_ID with your destination account ID, Source_Account_ID with your source account ID, and Role_Name with the name of your IAM role.

Conclusion

Setting up Amazon S3 Cross Region Replication between two accounts can be tricky, but by ensuring the correct bucket policies, IAM role permissions, and replication configurations, you can resolve most issues. Always remember to check and double-check each step of the process. Happy data replicating!

Tags:

#AmazonS3 #CrossRegionReplication #DataScience #AWS #IAM #CRR #BucketPolicy #Troubleshooting

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