Request Syntax URI Request Parameters Request Body Response Syntax Response Elements Errors See Also

CreateSession

Creates a session that establishes temporary security credentials to support fast authentication and authorization for the Zonal endpoint APIs on directory buckets. For more information about Zonal endpoint APIs that include the Availability Zone in the request endpoint, see S3 Express One Zone APIs in the Amazon S3 User Guide.

To make Zonal endpoint API requests on a directory bucket, use the CreateSession API operation. Specifically, you grant s3express:CreateSession permission to a bucket in a bucket policy or an IAM identity-based policy. Then, you use IAM credentials to make the CreateSession API request on the bucket, which returns temporary security credentials that include the access key ID, secret access key, session token, and expiration. These credentials have associated permissions to access the Zonal endpoint APIs. After the session is created, you don’t need to use other policies to grant permissions to each Zonal endpoint API individually. Instead, in your Zonal endpoint API requests, you sign your requests by applying the temporary security credentials of the session to the request headers and following the SigV4 protocol for authentication. You also apply the session token to the x-amz-s3session-token request header for authorization. Temporary security credentials are scoped to the bucket and expire after 5 minutes. After the expiration time, any calls that you make with those credentials will fail. You must use IAM credentials again to make a CreateSession API request that generates a new set of temporary credentials for use. Temporary credentials cannot be extended or refreshed beyond the original specified interval.

If you use AWS SDKs, SDKs handle the session token refreshes automatically to avoid service interruptions when a session expires. We recommend that you use the AWS SDKs to initiate and manage requests to the CreateSession API. For more information, see Performance guidelines and design patterns in the Amazon S3 User Guide.

Note

You must make requests for this API operation to the Zonal endpoint. These endpoints support virtual-hosted-style requests in the format https://bucket_name.s3express-az_id.region.amazonaws.com. Path-style requests are not supported. For more information, see Regional and Zonal endpoints in the Amazon S3 User Guide.
CopyObject API operation - Unlike other Zonal endpoint APIs, the CopyObject API operation doesn't use the temporary security credentials returned from the CreateSession API operation for authentication and authorization. For information about authentication and authorization of the CopyObject API operation on directory buckets, see CopyObject.
HeadBucket API operation - Unlike other Zonal endpoint APIs, the HeadBucket API operation doesn't use the temporary security credentials returned from the CreateSession API operation for authentication and authorization. For information about authentication and authorization of the HeadBucket API operation on directory buckets, see HeadBucket.

Permissions

To obtain temporary security credentials, you must create a bucket policy or an IAM identity-based policy that grants s3express:CreateSession permission to the bucket. In a policy, you can have the s3express:SessionMode condition key to control who can create a ReadWrite or ReadOnly session. For more information about ReadWrite or ReadOnly sessions, see x-amz-create-session-mode. For example policies, see Example bucket policies for S3 Express One Zone and AWS Identity and Access Management (IAM) identity-based policies for S3 Express One Zone in the Amazon S3 User Guide.

To grant cross-account access to Zonal endpoint APIs, the bucket policy should also grant both accounts the s3express:CreateSession permission.

HTTP Host header syntax

Directory buckets - The HTTP Host header syntax is Bucket_name.s3express-az_id.region.amazonaws.com.

Request Syntax


GET /?session HTTP/1.1
Host: Bucket.s3.amazonaws.com
x-amz-create-session-mode: SessionMode

URI Request Parameters

The request uses the following URI parameters.

Bucket

The name of the bucket that you create a session for.

Required: Yes

x-amz-create-session-mode

Specifies the mode of the session that will be created, either ReadWrite or ReadOnly. By default, a ReadWrite session is created. A ReadWrite session is capable of executing all the Zonal endpoint APIs on a directory bucket. A ReadOnly session is constrained to execute the following Zonal endpoint APIs: GetObject, HeadObject, ListObjectsV2, GetObjectAttributes, ListParts, and ListMultipartUploads.

Valid Values: ReadOnly | ReadWrite

Request Body

The request does not have a request body.

Response Syntax


HTTP/1.1 200
<?xml version="1.0" encoding="UTF-8"?>
<CreateSessionOutput>
   <Credentials>
      <AccessKeyId>string</AccessKeyId>
      <Expiration>timestamp</Expiration>
      <SecretAccessKey>string</SecretAccessKey>
      <SessionToken>string</SessionToken>
   </Credentials>
</CreateSessionOutput>

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in XML format by the service.

CreateSessionOutput

Root level tag for the CreateSessionOutput parameters.

Required: Yes

Credentials

The established temporary security credentials for the created session.

Type: SessionCredentials data type

Errors

NoSuchBucket

The specified bucket does not exist.

HTTP Status Code: 404