Setting the Amazon Web Services Region for the Amazon SDK for Java 2.x - Amazon SDK for Java 2.x
Explicitly configure an Amazon Web Services RegionDetermine Region from environmentCheck for service availabilityChoose a specific endpoint
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Setting the Amazon Web Services Region for the Amazon SDK for Java 2.x

SDK clients connect to an Amazon Web Services service in a specific Amazon Web Services Region that you specify when you create the client. This configuration allows your application to interact with Amazon resources in that geographical area. When you create a service client without explicitly setting a Region, the SDK uses the default Region from your external configuration.

Explicitly configure an Amazon Web Services Region

To explicitly set a Region, we recommend that you use the constants defined in the Region class. This is an enumeration of all publicly available regions.

To create a client with an enumerated Region from the class, use the client builder's region method.

Ec2Client ec2 = Ec2Client.builder()
          .region(Region.US_WEST_2)
          .build();

If the Region you want to use isn’t one of the enumerations in the Region class, you can create a new Region by using the static of method. This method allows you access to new Regions without upgrading the SDK. 

Region newRegion = Region.of("us-east-42");
Ec2Client ec2 = Ec2Client.builder()
          .region(newRegion)
          .build();
Note

After you build a client with the builder, it’s immutable and the Amazon Web Services Region cannot be changed. If you need to work with multiple Amazon Web Services Regions for the same service, you should create multiple clients—​one per Region.

Let the SDK automatically determine the default Amazon Web Services Region from the environment

When your code runs on Amazon EC2 or Amazon Lambda, you might want to configure clients to use the same Amazon Web Services Region that your code is running on. This decouples your code from the environment it’s running in and makes it easier to deploy your application to multiple Amazon Web Services Regions for lower latency or redundancy.

To use the default Amazon Web Services Region provider chain to determine the Region from the environment, use the client builder’s create method.

Ec2Client ec2 = Ec2Client.create();

You can also configure the client in other ways, but not set the Region. The SDK picks up the Amazon Web Services Region by using the default region provider chain:

Ec2Client ec2Client = Ec2Client.builder()
        .credentialsProvider(ProfileCredentialsProvider.builder()
                .profileName("my-profile")
                .build())
        .build();

If you don’t explicitly set an Amazon Web Services Region by using the region method, the SDK consults the default region provider chain to determine the Region to use.

Understanding the default Amazon Web Services Region provider chain

The SDK takes the following steps to look for an Amazon Web Services Region:

  1. Any explicit Region set by using the region method on the builder itself takes precedence over anything else.

  2. The SDK looks for the JVM system property aws.region and uses its value if found.

  3. The AWS_REGION environment variable is checked. If it’s set, that Region is used to configure the client.

    Note

    The Lambda container sets this environment variable.

  4. The SDK checks the active profile in the Amazon shared config and credentials files. If the region property is present, the SDK uses it.

    The default profile is the active profile unless overridden by AWS_PROFILE environment variable or aws.profile JVM system property. If the SDK finds the region property in both files for the same profile (including the default profile), the SDK uses the value in the shared credentials file.

  5. The SDK attempts to use the Amazon EC2 instance metadata service (IMDS) to determine the Region of the currently running Amazon EC2 instance.

    • For greater security, you should disable the SDK from attempting to use version 1 of IMDS. You use the same setting to disable version 1 that are described in the Securely acquire IAM role credentials section.

  6. If the SDK still hasn’t found a Region by this point, client creation fails with an exception.

When developing Amazon applications, a common approach is to use the shared configuration file to set the Region for local development, and rely on the default region provider chain to determine the Region when the application runs on Amazon infrastructure. This greatly simplifies client creation and keeps your application portable.

Check to see if a service is available in a Region

To see if a particular Amazon Web Services service is available in a Region, use the static serviceMetadata method on a service client:

DynamoDbClient.serviceMetadata().regions().forEach(System.out::println);

The previous snippet prints out a long list of Amazon Web Services Region codes that have the DynamoDB service:

af-south-1
ap-east-1
ap-northeast-1
ap-northeast-2
ap-northeast-3
ap-south-1
ap-south-2
ap-southeast-1
...

You can use a code to look up the Region class enumeration for the Region you need your service client to use.

For example, if you want to work with DynamoDB in the Region with the code ap-northeast-2, create your DynamoDB client with at least the following configuration:

DynamoDbClient ddb = DynamoDbClient.builder()
    .region(Region.AP_NORTHEAST_2)
    .build();

Choose a specific endpoint

In certain situations—such as to test preview features of a service before the features graduate to general availability—you may need to specify a specific endpoint in a Region. In these situations, service clients can be configured by calling the endpointOverride method.

For example, to configure an Amazon EC2 client to use the Europe (Ireland) Region with a specific endpoint, use the following code.

Ec2Client ec2 = Ec2Client.builder()
               .region(Region.EU_WEST_1)
               .endpointOverride(URI.create("https://ec2.eu-west-1.amazonaws.com"))
               .build();

See Regions and Endpoints for the current list of regions and their corresponding endpoints for all Amazon services.