Using Amazon S3 dual-stack endpoints

Amazon S3 dual-stack endpoints support requests to S3 buckets over IPv6 and IPv4. This section describes how to use dual-stack endpoints.

Amazon S3 dual-stack endpoints

When you make a request to a dual-stack endpoint, the bucket URL resolves to an IPv6 or an IPv4 address. For more information about accessing a bucket over IPv6, see Making requests to Amazon S3 over IPv6.

When using the REST API, you directly access an Amazon S3 endpoint by using the endpoint name (URI). You can access an S3 bucket through a dual-stack endpoint by using a virtual hosted-style or a path-style endpoint name. Amazon S3 supports only regional dual-stack endpoint names, which means that you must specify the region as part of the name.

Use the following naming conventions for the dual-stack virtual hosted-style and path-style endpoint names:

For more information, about endpoint name style, see Accessing and listing an Amazon S3 bucket . For a list of Amazon S3 endpoints, see Regions and Endpoints in the AWS General Reference.

When using the AWS Command Line Interface (AWS CLI) and AWS SDKs, you can use a parameter or flag to change to a dual-stack endpoint. You can also specify the dual-stack endpoint directly as an override of the Amazon S3 endpoint in the config file. The following sections describe how to use dual-stack endpoints from the AWS CLI and the AWS SDKs.

Using dual-stack endpoints from the AWS CLI

This section provides examples of AWS CLI commands used to make requests to a dual-stack endpoint. For instructions on setting up the AWS CLI, see Developing with Amazon S3 using the AWS CLI.

You set the configuration value use_dualstack_endpoint to true in a profile in your AWS Config file to direct all Amazon S3 requests made by the s3 and s3api AWS CLI commands to the dual-stack endpoint for the specified region. You specify the region in the config file or in a command using the --region option.

When using dual-stack endpoints with the AWS CLI, both path and virtual addressing styles are supported. The addressing style, set in the config file, controls if the bucket name is in the hostname or part of the URL. By default, the CLI will attempt to use virtual style where possible, but will fall back to path style if necessary. For more information, see AWS CLI Amazon S3 Configuration.

You can also make configuration changes by using a command, as shown in the following example, which sets use_dualstack_endpoint to true and addressing_style to virtual in the default profile.

$ aws configure set default.s3.use_dualstack_endpoint true
$ aws configure set default.s3.addressing_style virtual

If you want to use a dual-stack endpoint for specified AWS CLI commands only (not all commands), you can use either of the following methods:

Using dual-stack endpoints from the AWS SDKs

This section provides examples of how to access a dual-stack endpoint by using the AWS SDKs.

AWS SDK for Java dual-stack endpoint example

The following example shows how to enable dual-stack endpoints when creating an Amazon S3 client using the AWS SDK for Java.

For instructions on creating and testing a working Java sample, see Getting Started in the AWS SDK for Java Developer Guide.

import com.amazonaws.AmazonServiceException;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;

public class DualStackEndpoints {

    public static void main(String[] args) {
        Regions clientRegion = Regions.DEFAULT_REGION;
        String bucketName = "*** Bucket name ***";

        try {
            // Create an Amazon S3 client with dual-stack endpoints enabled.
            AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                    .withCredentials(new ProfileCredentialsProvider())
                    .withRegion(clientRegion)
                    .withDualstackEnabled(true)
                    .build();

            s3Client.listObjects(bucketName);
        } catch (AmazonServiceException e) {
            // The call was transmitted successfully, but Amazon S3 couldn't process
            // it, so it returned an error response.
            e.printStackTrace();
        } catch (SdkClientException e) {
            // Amazon S3 couldn't be contacted for a response, or the client
            // couldn't parse the response from Amazon S3.
            e.printStackTrace();
        }
    }
}

If you are using the AWS SDK for Java on Windows, you might have to set the following Java virtual machine (JVM) property:

java.net.preferIPv6Addresses=true

AWS .NET SDK dual-stack endpoint example

When using the AWS SDK for .NET you use the AmazonS3Config class to enable the use of a dual-stack endpoint as shown in the following example.

using Amazon;
using Amazon.S3;
using Amazon.S3.Model;
using System;
using System.Threading.Tasks;

namespace Amazon.DocSamples.S3
{
    class DualStackEndpointTest
    {
        private const string bucketName = "*** bucket name ***";
        // Specify your bucket region (an example region is shown).
        private static readonly RegionEndpoint bucketRegion = RegionEndpoint.USWest2;
        private static IAmazonS3 client;

        public static void Main()
        {
            var config = new AmazonS3Config
            {
                UseDualstackEndpoint = true,
                RegionEndpoint = bucketRegion
            };
            client = new AmazonS3Client(config);
            Console.WriteLine("Listing objects stored in a bucket");
            ListingObjectsAsync().Wait();
        }

        private static async Task ListingObjectsAsync()
        {
            try
            {
                var request = new ListObjectsV2Request
                {
                    BucketName = bucketName,
                    MaxKeys = 10
                };
                ListObjectsV2Response response;
                do
                {
                    response = await client.ListObjectsV2Async(request);

                    // Process the response.
                    foreach (S3Object entry in response.S3Objects)
                    {
                        Console.WriteLine("key = {0} size = {1}",
                            entry.Key, entry.Size);
                    }
                    Console.WriteLine("Next Continuation Token: {0}", response.NextContinuationToken);
                    request.ContinuationToken = response.NextContinuationToken;
                } while (response.IsTruncated == true);
            }
            catch (AmazonS3Exception amazonS3Exception)
            {
                Console.WriteLine("An AmazonS3Exception was thrown. Exception: " + amazonS3Exception.ToString());
            }
            catch (Exception e)
            {
                Console.WriteLine("Exception: " + e.ToString());
            }
        }
    }
}

For information about setting up and running the code examples, see Getting Started with the AWS SDK for .NET in the AWS SDK for .NET Developer Guide.

Using dual-stack endpoints from the REST API

For information about making requests to dual-stack endpoints by using the REST API, see Making requests to dual-stack endpoints by using the REST API.