Working with AWS Credentials

To make requests to Amazon Web Services, you must supply AWS credentials to the AWS SDK for Java. You can do this in the following ways:

Using the Default Credential Provider Chain

When you initialize a new service client without supplying any arguments, the AWS SDK for Java attempts to find AWS credentials by using the default credential provider chain implemented by the DefaultAWSCredentialsProviderChain class. The default credential provider chain looks for credentials in this order:

Setting Credentials

To be able to use AWS credentials, they must be set in at least one of the preceding locations. For information about setting credentials, see the following topics:

Setting an Alternate Credentials Profile

The AWS SDK for Java uses the default profile by default, but there are ways to customize which profile is sourced from the credentials file.

You can use the AWS Profile environment variable to change the profile loaded by the SDK.

For example, on Linux, macOS, or Unix you would run the following command to change the profile to myProfile.

export AWS_PROFILE="myProfile"

On Windows you would use the following.

set AWS_PROFILE="myProfile"

Setting the AWS_PROFILE environment variable affects credential loading for all officially supported AWS SDKs and Tools (including the AWS CLI and the AWS CLI for PowerShell). To change only the profile for a Java application, you can use the system property aws.profile instead.

Setting an Alternate Credentials File Location

The AWS SDK for Java loads AWS credentials automatically from the default credentials file location. However, you can also specify the location by setting the AWS_CREDENTIAL_PROFILES_FILE environment variable with the full path to the credentials file.

You can use this feature to temporarily change the location where the AWS SDK for Java looks for your credentials file (for example, by setting this variable with the command line). Or you can set the environment variable in your user or system environment to change it for the user or systemwide.

To override the default credentials file location

AWS Credentials File Format

When you use the aws configure command to create an AWS credentials file, the command creates a file with the following format.

[default]
aws_access_key_id={YOUR_ACCESS_KEY_ID}
aws_secret_access_key={YOUR_SECRET_ACCESS_KEY}

[profile2]
aws_access_key_id={YOUR_ACCESS_KEY_ID}
aws_secret_access_key={YOUR_SECRET_ACCESS_KEY}

The profile name is specified in square brackets (for example, [default]), followed by the configurable fields in that profile as key-value pairs. You can have multiple profiles in your credentials file, which can be added or edited using aws configure --profile PROFILE_NAME to select the profile to configure.

You can specify additional fields, such as aws_session_token, metadata_service_timeout, and metadata_service_num_attempts. These are not configurable with the CLI—you must edit the file by hand if you want to use them. For more information about the configuration file and its available fields, see Configuring the AWS Command Line Interface in the AWS CLI User Guide.

Loading Credentials

After you set credentials, you can load them by using the default credential provider chain.

To do this, you instantiate an AWS Service client without explicitly providing credentials to the builder, as follows.

AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                       .withRegion(Regions.US_WEST_2)
                       .build();

Specifying a Credential Provider or Provider Chain

You can specify a credential provider that is different from the default credential provider chain by using the client builder.

You provide an instance of a credentials provider or provider chain to a client builder that takes an AWSCredentialsProvider interface as input. The following example shows how to use environment credentials specifically.

AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                       .withCredentials(new EnvironmentVariableCredentialsProvider())
                       .build();

For the full list of AWS SDK for Java-supplied credential providers and provider chains, see All Known Implementing Classes in AWSCredentialsProvider.

Explicitly Specifying Credentials

If the default credential chain or a specific or custom provider or provider chain doesn’t work for your code, you can set credentials that you supply explicitly. If you’ve retrieved temporary credentials using AWS STS, use this method to specify the credentials for AWS access.

The following is an example.

BasicAWSCredentials awsCreds = new BasicAWSCredentials("access_key_id", "secret_key_id");
AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                        .withCredentials(new AWSStaticCredentialsProvider(awsCreds))
                        .build();

When using temporary credentials obtained from STS, create a BasicSessionCredentials object, passing it the STS-supplied credentials and session token.

BasicSessionCredentials sessionCredentials = new BasicSessionCredentials(
   session_creds.getAccessKeyId(),
   session_creds.getSecretAccessKey(),
   session_creds.getSessionToken());

AmazonS3 s3 = AmazonS3ClientBuilder.standard()
                        .withCredentials(new AWSStaticCredentialsProvider(sessionCredentials))
                        .build();

More Info