CloudFormation support for S3 replication to multiple destination buckets

Question

As per https://aws.amazon.com/blogs/aws/new-amazon-s3-replication-adds-support-for-multiple-destination-buckets/, S3 now supports replication to multiple destination buckets, and according to the press release, it should be supported in CloudFormation.  
  
However when adding the following configuration to CloudFormation:

```yaml
PublicBucket:
    Type: AWS::S3::Bucket
    DependsOn: GlobalBuckets
    Properties:
      BucketName: !Sub learning-${Environment}-${AWS::Region}-public-web${Suffix}
      VersioningConfiguration:
        Status: Enabled
      ReplicationConfiguration:
        Role: !GetAtt PublicBucketReplicationRole.Arn
        Rules:
          - Id: ap-southeast-1
            Status: Enabled
            Destination:
              Bucket: !Sub arn:aws:s3:::learning-${Environment}-ap-southeast-1-public-web
          - Id: ap-southeast-2
            Status: Enabled
            Destination:
              Bucket: !Sub arn:aws:s3:::learning-${Environment}-ap-southeast-2-public-web
```

The deployment fails with the following error:  
  
Number of distinct destination bucket ARNs cannot exceed 1 (Service: Amazon S3; Status Code: 400; Error Code: InvalidRequest; Request ID: EA29054861FE2AD9; S3 Extended Request ID: lbdTf_mHpoDLdCKp0w_bh38gjfcCKNF2Z7PmoIS/C6aMYGfdi1o8N1MS/MReNTRseuDPbo2y6LU=; Proxy: null)  
  
The configuration works if I limit to a single replication rule.  
  
Looks like this is actually NOT yet supported in CloudFormation?

Answer

Found the solution - it is supported as of now, but not well documented.  
  
Basically you need to ensure you force rules to use the new Replication Rules V2 schema to support multiple destination buckets.  As per https://docs.aws.amazon.com/AmazonS3/latest/dev/replication-add-config.html#replication-backward-compat-considerations V2 schema is forced by specifying the `Filter` property on each rule.  
  
Once you do this you need to ensure you add a number of configuration properties for each rule as per the example below, and you also need to ensure each `Priority` is a unique value.  
  
Here is a working example:

```yaml
Resources:
  PublicBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: foo-sandbox-us-west-2-public-web
      VersioningConfiguration:
        Status: Enabled
      ReplicationConfiguration:
        Role: !GetAtt PublicBucketReplicationRole.Arn
        Rules:
          - Id: ap-southeast-1
            Status: Enabled
            DeleteMarkerReplication:
              Status: Enabled
            Priority: 1
            Filter:
              Prefix: ''
            Destination:
              Bucket: arn:aws:s3:::foo-sandbox-ap-southeast-1-public-web
          - Id: ap-southeast-2
            Status: Enabled
            DeleteMarkerReplication:
              Status: Enabled
            Priority: 2
            Filter:
              Prefix: ''
            Destination:
              Bucket: arn:aws:s3:::foo-sandbox-ap-southeast-2-public-web
  PublicBucketReplicationRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Principal:
              Service: s3.amazonaws.com
            Action: sts:AssumeRole
      Policies:
        - PolicyName: Allow
          PolicyDocument:
            Statement:
              - Effect: Allow
                Action:
                - s3:GetReplicationConfiguration
                - s3:ListBucket
                Resource: arn:aws:s3:::foo-sandbox-us-west-2-public-web
              - Effect: Allow
                Action:
                - s3:GetObjectVersionForReplication
                - s3:GetObjectVersionAcl
                - s3:GetObjectVersionTagging
                Resource: arn:aws:s3:::foo-sandbox-us-west-2-public-web/*
              - Effect: Allow
                Action:
                - s3:GetObjectVersionTagging
                - s3:ReplicateObject
                - s3:ReplicateDelete
                - s3:ReplicateTags
                Resource: arn:aws:s3:::foo-sandbox-*-public-web/*
```

CloudFormation support for S3 replication to multiple destination buckets

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