[BUG] Automatic S3 endpoint routing

[magersh]

Describe the bug

Endpoints: As of 11/5/25, OpenSearch supports a single S3 endpoint format style of s3.region.amazonaws.com that matches S3 general purpose bucket format. However, all other other S3 bucket types (directory buckets, outposts buckets) use alternate endpoint formats including s3express-control.region.amazonaws.com and s3-outposts.region.amazonaws.com respectively.

Request: Remove the existing single format style, and update to support multi formats. One method could be using a SDK version for endpoint routing that's at or higher than 3/31/2025. It constructs the endpoint format based on the bucket name provided and routes (based on bucket name or access point name or alias)

AWS SDK References
aws/aws-sdk-js-v3@7f2cfea (3/31/25 for access points or higher )

OpenSearch References
https://github.com/opensearch-project/OpenSearch/blob/main/plugins/repository-s3/src/main/java/org/opensearch/repositories/s3/S3ClientSettings.java

https://github.com/opensearch-project/OpenSearch/blob/main/plugins/repository-s3/src/main/java/org/opensearch/repositories/s3/S3Repository.java

https://github.com/opensearch-project/OpenSearch/blob/main/plugins/repository-s3/src/main/java/org/opensearch/repositories/s3/S3Service.java

Related component

No response

To Reproduce

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4. See error

Expected behavior

more than 1 S3 endpoint is supported

Additional Details

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[magersh]

This would solve for #19897 as well

[andrross]

Catch All Triage - 1 2 3

[cwperks]

Thank you for the detail @magersh. I agree that this should be delegated to the AWS SDK for endpoint creation. I have been spiking on that here: #20345