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The HEAD operation retrieves metadata from an object without returning the
object itself. This operation is useful if you're interested only in an object's metadata.
A HEAD request has the same options as a GET operation on an object.
The response is identical to the GET response except that there is no response
body. Because of this, if the HEAD request generates an error, it returns a
generic code, such as 400 Bad Request, 403 Forbidden, 404 Not Found,
405 Method Not Allowed, 412 Precondition Failed, or 304 Not Modified.
It's not possible to retrieve the exact exception of these error codes.
Request headers are limited to 8 KB in size. For more information, see Common Request Headers.
Directory buckets - For directory buckets, 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/key-name. Path-style requests are not supported. For more information, see Regional
and Zonal endpoints in the Amazon S3 User Guide.
General purpose bucket permissions - To use HEAD, you must have the
s3:GetObject permission. You need the relevant read object (or version) permission
for this operation. For more information, see Actions,
resources, and condition keys for Amazon S3 in the Amazon S3 User Guide.
If the object you request doesn't exist, the error that 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 error.
If you don’t have the s3:ListBucket permission, Amazon S3 returns an HTTP status
code 403 Forbidden 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.
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 HEAD 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 encrypt an object by using server-side encryption with customer-provided encryption keys (SSE-C) when you store the object in Amazon S3, then when you retrieve the metadata from the object, you must use the following headers to provide the encryption key for the server to be able 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, only server-side encryption
with Amazon S3 managed keys (SSE-S3) (AES256) is supported.
If the current version of the object is a delete marker, Amazon S3 behaves as if the
object was deleted and includes x-amz-delete-marker: true in the response.
If the specified version is a delete marker, the response returns a 405 Method
Not Allowed error and the Last-Modified: timestamp response header.
Directory buckets - Delete marker is not supported by directory buckets.
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.
Directory buckets - The HTTP Host header syntax is Bucket_name.s3express-az_id.region.amazonaws.com.
The following actions are related to HeadObject:
This is an asynchronous operation using the standard naming convention for .NET 4.5 or higher. For .NET 3.5 the operation is implemented as a pair of methods using the standard naming convention of BeginGetObjectMetadata and EndGetObjectMetadata.
Namespace: Amazon.S3
Assembly: AWSSDK.S3.dll
Version: 3.x.y.z
public virtual Task<GetObjectMetadataResponse> GetObjectMetadataAsync( String bucketName, String key, CancellationToken cancellationToken )
The name of the bucket that contains the object. Directory buckets - When you use this operation with a directory bucket, you must use virtual-hosted-style requests in the format Bucket_name.s3express-az_id.region.amazonaws.com. Path-style requests are not supported. Directory bucket names must be unique in the chosen Availability Zone. Bucket names must follow the format bucket_base_name--az-id--x-s3 (for example, DOC-EXAMPLE-BUCKET--usw2-az1--x-s3). For information about bucket naming restrictions, see Directory bucket naming rules in the Amazon S3 User Guide. Access points - When you use this action with an access point, you must provide the alias of the access point in place of the bucket name or specify the access point ARN. When using the access point ARN, you must direct requests to the access point hostname. The access point hostname takes the form AccessPointName-AccountId.s3-accesspoint.Region.amazonaws.com. When using this action with an access point through the Amazon Web Services SDKs, you provide the access point ARN in place of the bucket name. For more information about access point ARNs, see Using access points in the Amazon S3 User Guide. Access points and Object Lambda access points are not supported by directory buckets. S3 on Outposts - When you use this action with Amazon S3 on Outposts, you must direct requests to the S3 on Outposts hostname. The S3 on Outposts hostname takes the form AccessPointName-AccountId.outpostID.s3-outposts.Region.amazonaws.com. When you use this action with S3 on Outposts through the Amazon Web Services SDKs, you provide the Outposts access point ARN in place of the bucket name. For more information about S3 on Outposts ARNs, see What is S3 on Outposts? in the Amazon S3 User Guide.
The object key.
A cancellation token that can be used by other objects or threads to receive notice of cancellation.
.NET Core App:
Supported in: 3.1
.NET Standard:
Supported in: 2.0
.NET Framework:
Supported in: 4.5