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The HEAD action retrieves metadata from an object without returning the object itself. This action is useful if you're only interested in an object's metadata. To use HEAD, you must have READ access to the object.
A HEAD
request has the same options as a GET
action 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 404 Not Found
or 403 Forbidden
code. It is not possible to retrieve the exact exception beyond these error codes.
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:
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).
Encryption request headers, like x-amz-server-side-encryption
, should
not be sent for GET requests if your object uses server-side encryption with KMS keys
(SSE-KMS) or server-side encryption with Amazon S3–managed encryption keys (SSE-S3).
If your object does use these types of keys, you’ll get an HTTP 400 BadRequest error.
The last modified property in this case is the creation date of the object.
Request headers are limited to 8 KB in size. For more information, see Common Request Headers.
Consider the following when using request headers:
Consideration 1 – If both of the If-Match
and If-Unmodified-Since
headers are present in the request as follows:
If-Match
condition evaluates to true
, and;
If-Unmodified-Since
condition evaluates to false
;
Then Amazon S3 returns 200 OK
and the data requested.
Consideration 2 – If both of the If-None-Match
and If-Modified-Since
headers are present in the request as follows:
If-None-Match
condition evaluates to false
, and;
If-Modified-Since
condition evaluates to true
;
Then Amazon S3 returns the 304 Not Modified
response code.
For more information about conditional requests, see RFC 7232.
Permissions
You need the relevant read object (or version) permission for this operation. For more information, see Specifying Permissions in a Policy. If the object 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 ("no such key") error.
If you don’t have the s3:ListBucket
permission, Amazon S3 returns an
HTTP status code 403 ("access denied") error.
The following actions are related to HeadObject
:
For .NET Core this operation is only available in asynchronous form. Please refer to GetObjectMetadataAsync.
Namespace: Amazon.S3
Assembly: AWSSDK.S3.dll
Version: 3.x.y.z
public virtual GetObjectMetadataResponse GetObjectMetadata( GetObjectMetadataRequest request )
Container for the necessary parameters to execute the GetObjectMetadata service method.
.NET Framework:
Supported in: 4.5, 4.0, 3.5