CreateSession authorization - Amazon Simple Storage Service
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CreateSession authorization

Amazon S3 Express One Zone supports both Amazon Identity and Access Management (Amazon IAM) authorization and session-based authorization:

  • To use Regional endpoint API operations (bucket-level, or control plane, operations) with S3 Express One Zone, you use the IAM authorization model, which doesn't involve session management. Permissions are granted for actions individually. For more information, see Amazon Identity and Access Management (IAM) for S3 Express One Zone.

  • To use Zonal endpoint API operations (object-level, or data plane, operations), you use the CreateSession API operation to create and manage sessions that are optimized for low-latency authorization of data requests. To retrieve and use a session token, you must allow the s3express:CreateSession action for your directory bucket in an identity-based policy or a bucket policy. For more information, see Amazon Identity and Access Management (IAM) for S3 Express One Zone. If you're accessing S3 Express One Zone in the Amazon S3 console, through the Amazon Command Line Interface (Amazon CLI), or by using the Amazon SDKs, S3 Express One Zone creates a session on your behalf.

If you use the Amazon S3 REST API, you can then use the CreateSession API operation to obtain temporary security credentials that include an access key ID, a secret access key, a session token, and an expiration time. The temporary credentials provide the same permissions as long-term security credentials, such as IAM user credentials, but temporary security credentials must include a session token.

Session Mode

Session mode defines the scope of the session. In your bucket policy, you can specify the s3express:SessionMode condition key to control who can create a ReadWrite or ReadOnly session. For more information about ReadWrite or ReadOnly sessions, see the x-amz-create-session-mode parameter for CreateSession in the Amazon S3 API Reference. For more information about the bucket policy to create, see Example directory bucket policies for S3 Express One Zone.

Session Token

When you make a call by using temporary security credentials, the call must include a session token. The session token is returned along with the temporary credentials. A session token is scoped to your directory bucket and is used to verify that the security credentials are valid and haven't expired. To protect your sessions, temporary security credentials expire after 5 minutes.

CopyObject and HeadBucket

Temporary security credentials are scoped to a specific directory bucket and are automatically enabled for all Zonal (object-level) operation API calls to a given directory bucket. Unlike other Zonal endpoint API operations, CopyObject and HeadBucket don't use CreateSession authentication. All CopyObject and HeadBucket requests must be authenticated and signed by using IAM credentials. However, CopyObject and HeadBucket are still authorized by s3express:CreateSession, like other Zonal endpoint API operations.

For more information, see CreateSession in the Amazon Simple Storage Service API Reference.