Problem

Is CFT supports S3 multi-region access points (MRAP) that is a cluster of buckets in different regions.

Resolution

This is not supported in 3.6 but there is a workaround for it:

In Transfer CFT 3.10, AWS SDK has been updated and support the ARN format for the bucket.
So using the supported format 's3://bucket.region' for WORKINGDIR in CFT configuration, the bucket part can be set to the MRAP ARN, and since region is not used, it can be left empty.

From official documentation, https://docs.aws.amazon.com/AmazonS3/latest/userguide/MultiRegionAccessPointRequests.html
The ARN of a MRAP is constructed as following:

• arn:aws:s3::<account-id>:accesspoint/<MRAP_alias>
  for example: arn:aws:s3::123456789012:accesspoint/mfzwi23gnjvgw.mrap

Since slashes '/' in path are not really welcome and per this documentation: https://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html
The slash can be replaced by a colon:

• arn:aws:s3::<account-id>:accesspoint:<MRAP_alias>
  for example: arn:aws:s3::123456789012:accesspoint:mfzwi23gnjvgw.mrap

In CFT configuration, to respect the format of WORKINGDIR matching s3://bucket.region

• s3://arn:aws:s3::<account-id>:accesspoint:<MRAP_alias>.
  for example: s3://arn:aws:s3::123456789012:accesspoint:mfzwi23gnjvgw.mrap.

The last dot is important so that CFT does not consider 'mrap' extension as the given region.

It tests successfully the use of the ARN of a MRAP.