How to use IAM role with AWS Java SDK

It's been a while, but this is not currently the case, it is now possible to use assume role with the Java SDK with a user. You can configure credentials in your .aws/credentials file as follows:

[useraccount]
aws_access_key_id=<key>
aws_secret_access_key=<secret>

[somerole]
role_arn=<the ARN of the role you want to assume>
source_profile=useraccount

Then, when you launch, set an environment variable: AWS_PROFILE=somerole

The SDK will use the credentials defined in useraccount to call assumeRole with the role_arn you provided. You'll of course need to be sure that the user with those credentials has the permissions to assume that role.

Note that if you're not including the full Java SDK in your project (i.e. you're including just the libraries for the services you need), you also need to include the aws-java-sdk-sts library in your classpath for this to work.

It is also possible to do all of this programmatically using STSAssumeRoleSessionCredentialsProvider, but this would require you to directly configure all of the services so it might not be as convenient as the profile approach which should just work for all services.

You can use role based authentication only on EC2 Instances, ECS Containers and Lambda functions. It is not possible to use them locally or on on premise servers.

DefaultAWSCredentialsProviderChain will automatically pick the EC2 Instance Role if it can't find the credentials via any of other methods. You can also create a custom AWSCredentialsProviderChain object with only injecting a instance of InstanceProfileCredentialsProvider to it like here

AWSCredentialsProviderChain myCustomChain = new AWSCredentialsProviderChain(new InstanceProfileCredentialsProvider());

For more info: https://docs.aws.amazon.com/java-sdk/latest/developer-guide/java-dg-roles.html