quick S3 region to endpoint mapping

s3_endpoints.json

{
  "us-east-2": "s3.us-east-2.amazonaws.com",
  "us-east-1": "s3.amazonaws.com",
  "us-west-2": "s3-us-west-2.amazonaws.com",
  "ca-central-1": "s3.ca-central-1.amazonaws.com",
  "ap-south-1": "s3.ap-south-1.amazonaws.com",
  "ap-northeast-2": "s3.ap-northeast-2.amazonaws.com",
  "ap-southeast-1": "s3-ap-southeast-1.amazonaws.com",
  "ap-southeast-2": "s3-ap-southeast-2.amazonaws.com",
  "ap-northeast-1": "s3-ap-northeast-1.amazonaws.com",
  "eu-central-1": "s3.eu-central-1.amazonaws.com",
  "eu-west-1": "s3-eu-west-1.amazonaws.com",
  "sa-east-1": "s3-sa-east-1.amazonaws.com"
}

See http://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region for latest table.