AmazonS3Client.GetObjectAttributesAsync (GetObjectAttributesRequest, CancellationToken)

Method

Retrieves all of the metadata from an object without returning the object itself. This operation is useful if you're interested only in an object's metadata.

GetObjectAttributes combines the functionality of HeadObject and ListParts. All of the data returned with both of those individual calls can be returned with a single call to GetObjectAttributes.

Permissions

• General purpose bucket permissions - To use GetObjectAttributes, you must have READ access to the object.

  The other permissions that you need to use this operation depend on whether the bucket is versioned and if a version ID is passed in the GetObjectAttributes request.

  • If you pass a version ID in your request, you need both the s3:GetObjectVersion and s3:GetObjectVersionAttributes permissions.

  • If you do not pass a version ID in your request, you need the s3:GetObject and s3:GetObjectAttributes permissions.

  For more information, see Specifying Permissions in a Policy in the Amazon S3 User Guide.

  If the object that you request does not exist, the error Amazon S3 returns depends on whether you also have the s3:ListBucket permission.

  • If you have the s3:ListBucket permission on the bucket, Amazon S3 returns an HTTP status code 404 Not Found ("no such key") error.

  • If you don't have the s3:ListBucket permission, Amazon S3 returns an HTTP status code 403 Forbidden ("access denied") error.

• Directory bucket permissions - To grant access to this API operation on a directory bucket, we recommend that you use the CreateSession API operation for session-based authorization. Specifically, you grant the s3express:CreateSession permission to the directory bucket in a bucket policy or an IAM identity-based policy. Then, you make the CreateSession API call on the bucket to obtain a session token. With the session token in your request header, you can make API requests to this operation. After the session token expires, you make another CreateSession API call to generate a new session token for use. Amazon Web Services CLI or SDKs create session and refresh the session token automatically to avoid service interruptions when a session expires. For more information about authorization, see CreateSession.

  If the object is encrypted with SSE-KMS, you must also have the kms:GenerateDataKey and kms:Decrypt permissions in IAM identity-based policies and KMS key policies for the KMS key.

Encryption

Encryption request headers, like x-amz-server-side-encryption, should not be sent for HEAD requests if your object uses server-side encryption with Key Management Service (KMS) keys (SSE-KMS), dual-layer server-side encryption with Amazon Web Services KMS keys (DSSE-KMS), or server-side encryption with Amazon S3 managed encryption keys (SSE-S3). The x-amz-server-side-encryption header is used when you PUT an object to S3 and want to specify the encryption method. If you include this header in a GET request for an object that uses these types of keys, you’ll get an HTTP 400 Bad Request error. It's because the encryption method can't be changed when you retrieve the object.

If you encrypted an object when you stored the object in Amazon S3 by using server-side encryption with customer-provided encryption keys (SSE-C), then when you retrieve the metadata from the object, you must use the following headers. These headers provide the server with the encryption key required to retrieve the object's metadata. The headers are:

• x-amz-server-side-encryption-customer-algorithm

• x-amz-server-side-encryption-customer-key

• x-amz-server-side-encryption-customer-key-MD5

For more information about SSE-C, see Server-Side Encryption (Using Customer-Provided Encryption Keys) in the Amazon S3 User Guide.

Directory bucket permissions - For directory buckets, there are only two supported options for server-side encryption: server-side encryption with Amazon S3 managed keys (SSE-S3) (AES256) and server-side encryption with KMS keys (SSE-KMS) (aws:kms). We recommend that the bucket's default encryption uses the desired encryption configuration and you don't override the bucket default encryption in your CreateSession requests or PUT object requests. Then, new objects are automatically encrypted with the desired encryption settings. For more information, see Protecting data with server-side encryption in the Amazon S3 User Guide. For more information about the encryption overriding behaviors in directory buckets, see Specifying server-side encryption with KMS for new object uploads.

Versioning

Directory buckets - S3 Versioning isn't enabled and supported for directory buckets. For this API operation, only the null value of the version ID is supported by directory buckets. You can only specify null to the versionId query parameter in the request.

Conditional request headers

Consider the following when using request headers:

• If both of the If-Match and If-Unmodified-Since headers are present in the request as follows, then Amazon S3 returns the HTTP status code 200 OK and the data requested:

  • If-Match condition evaluates to true.

  • If-Unmodified-Since condition evaluates to false.

  For more information about conditional requests, see RFC 7232.

• If both of the If-None-Match and If-Modified-Since headers are present in the request as follows, then Amazon S3 returns the HTTP status code 304 Not Modified:

  • If-None-Match condition evaluates to false.

  • If-Modified-Since condition evaluates to true.

  For more information about conditional requests, see RFC 7232.

HTTP Host header syntax

Directory buckets - The HTTP Host header syntax is Bucket-name.s3express-zone-id.region-code.amazonaws.com.

The following actions are related to GetObjectAttributes:

• GetObject

• GetObjectAcl

• GetObjectLegalHold

• GetObjectLockConfiguration

• GetObjectRetention

• GetObjectTagging

• HeadObject

• ListParts

Namespace: Amazon.S3
Assembly: AWSSDK.S3.dll
Version: 3.x.y.z