Amazon Simple Storage Service
API Reference (API Version 2006-03-01)

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HeadObject

The HEAD operation retrieves metadata from an object without returning the object itself. This operation 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 operation on an object. The response is identical to the GET response except that there is no response body.

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).

Note

Encryption request headers, like x-amz-server-side-encryption, should not be sent for GET requests if your object uses server-side encryption with AWS KMS–managed encryption 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.

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 s3:GetObject 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 will return a HTTP status code 404 ("no such key") error.

  • If you don’t have the s3:ListBucket permission, Amazon S3 will return a HTTP status code 403 ("access denied") error.

The following operation is related to HeadObject:

Request Syntax

HEAD /Key+?PartNumber=PartNumber&VersionId=VersionId HTTP/1.1 Host: Bucket.s3.amazonaws.com If-Match: IfMatch If-Modified-Since: IfModifiedSince If-None-Match: IfNoneMatch If-Unmodified-Since: IfUnmodifiedSince Range: Range x-amz-server-side-encryption-customer-algorithm: SSECustomerAlgorithm x-amz-server-side-encryption-customer-key: SSECustomerKey x-amz-server-side-encryption-customer-key-MD5: SSECustomerKeyMD5 x-amz-request-payer: RequestPayer

URI Request Parameters

The request requires the following URI parameters.

Bucket

The name of the bucket containing the object.

If-Match

Return the object only if its entity tag (ETag) is the same as the one specified, otherwise return a 412 (precondition failed).

If-Modified-Since

Return the object only if it has been modified since the specified time, otherwise return a 304 (not modified).

If-None-Match

Return the object only if its entity tag (ETag) is different from the one specified, otherwise return a 304 (not modified).

If-Unmodified-Since

Return the object only if it has not been modified since the specified time, otherwise return a 412 (precondition failed).

Key

The object key.

Length Constraints: Minimum length of 1.

partNumber

Part number of the object being read. This is a positive integer between 1 and 10,000. Effectively performs a 'ranged' HEAD request for the part specified. Useful querying about the size of the part and the number of parts in this object.

Range

Downloads the specified range bytes of an object. For more information about the HTTP Range header, go to http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35.

versionId

VersionId used to reference a specific version of the object.

x-amz-request-payer

Confirms that the requester knows that she or he will be charged for the request. Bucket owners need not specify this parameter in their requests. Documentation on downloading objects from requester pays buckets can be found at http://docs.aws.amazon.com/AmazonS3/latest/dev/ObjectsinRequesterPaysBuckets.html

Valid Values: requester

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

Specifies the algorithm to use to when encrypting the object (e.g., AES256).

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

Specifies the customer-provided encryption key for Amazon S3 to use in encrypting data. This value is used to store the object and then it is discarded; Amazon does not store the encryption key. The key must be appropriate for use with the algorithm specified in the x-amz-server-side​-encryption​-customer-algorithm header.

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

Specifies the 128-bit MD5 digest of the encryption key according to RFC 1321. Amazon S3 uses this header for a message integrity check to ensure the encryption key was transmitted without error.

Request Body

The request does not have a request body.

Response Syntax

HTTP/1.1 200 x-amz-delete-marker: DeleteMarker accept-ranges: AcceptRanges x-amz-expiration: Expiration x-amz-restore: Restore Last-Modified: LastModified Content-Length: ContentLength ETag: ETag x-amz-missing-meta: MissingMeta x-amz-version-id: VersionId Cache-Control: CacheControl Content-Disposition: ContentDisposition Content-Encoding: ContentEncoding Content-Language: ContentLanguage Content-Type: ContentType Expires: Expires x-amz-website-redirect-location: WebsiteRedirectLocation x-amz-server-side-encryption: ServerSideEncryption x-amz-server-side-encryption-customer-algorithm: SSECustomerAlgorithm x-amz-server-side-encryption-customer-key-MD5: SSECustomerKeyMD5 x-amz-server-side-encryption-aws-kms-key-id: SSEKMSKeyId x-amz-storage-class: StorageClass x-amz-request-charged: RequestCharged x-amz-replication-status: ReplicationStatus x-amz-mp-parts-count: PartsCount x-amz-object-lock-mode: ObjectLockMode x-amz-object-lock-retain-until-date: ObjectLockRetainUntilDate x-amz-object-lock-legal-hold: ObjectLockLegalHoldStatus

Response Elements

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

The response returns the following HTTP headers.

accept-ranges

Indicates that a range of bytes was specifed.

Cache-Control

Specifies caching behavior along the request/reply chain.

Content-Disposition

Specifies presentational information for the object.

Content-Encoding

Specifies what content encodings have been applied to the object and thus what decoding mechanisms must be applied to obtain the media-type referenced by the Content-Type header field.

Content-Language

The language the content is in.

Content-Length

Size of the body in bytes.

Content-Type

A standard MIME type describing the format of the object data.

ETag

An ETag is an opaque identifier assigned by a web server to a specific version of a resource found at a URL

Expires

The date and time at which the object is no longer cacheable.

Last-Modified

Last modified date of the object

x-amz-delete-marker

Specifies whether the object retrieved was (true) or was not (false) a Delete Marker. If false, this response header does not appear in the response.

x-amz-expiration

If the object expiration is configured (see PUT Bucket lifecycle), the response includes this header. It includes the expiry-date and rule-id key value pairs providing object expiration information. The value of the rule-id is URL encoded.

x-amz-missing-meta

This is set to the number of metadata entries not returned in x-amz-meta headers. This can happen if you create metadata using an API like SOAP that supports more flexible metadata than the REST API. For example, using SOAP, you can create metadata whose values are not legal HTTP headers.

x-amz-mp-parts-count

The count of parts this object has.

x-amz-object-lock-legal-hold

Specifies whether a legal hold is in effect for this object. This header is only returned if the requester has the s3:GetObjectLegalHold permission. This header is not returned if the specified version of this object has never had a legal hold applied. For more information about S3 Object Lock, see Object Lock.

Valid Values: ON | OFF

x-amz-object-lock-mode

The Object Lock mode, if any, that's in effect for this object. This header is only returned if the requester has the s3:GetObjectRetention permission. For more information about S3 Object Lock, see Object Lock.

Valid Values: GOVERNANCE | COMPLIANCE

x-amz-object-lock-retain-until-date

The date and time when the Object Lock retention period expires. This header is only returned if the requester has the s3:GetObjectRetention permission.

x-amz-replication-status

Amazon S3 can return this header if your request involves a bucket that is either a source or destination in a replication rule.

In replication you have a source bucket on which you configure replication and destination bucket where Amazon S3 stores object replicas. When you request an object (GetObject) or object metadata (HeadObject) from these buckets, Amazon S3 will return the x-amz-replication-status header in the response as follows:

  • If requesting object from the source bucket — Amazon S3 will return the x-amz-replication-status header if object in your request is eligible for replication.

    For example, suppose in your replication configuration you specify object prefix "TaxDocs" requesting Amazon S3 to replicate objects with key prefix "TaxDocs". Then any objects you upload with this key name prefix, for example "TaxDocs/document1.pdf", is eligible for replication. For any object request with this key name prefix Amazon S3 will return the x-amz-replication-status header with value PENDING, COMPLETED or FAILED indicating object replication status.

  • If requesting object from the destination bucket — Amazon S3 will return the x-amz-replication-status header with value REPLICA if object in your request is a replica that Amazon S3 created.

For more information, see Replication.

Valid Values: COMPLETE | PENDING | FAILED | REPLICA

x-amz-request-charged

If present, indicates that the requester was successfully charged for the request.

Valid Values: requester

x-amz-restore

If the object is an archived object (an object whose storage class is GLACIER), the response includes this header if either the archive restoration is in progress (see RestoreObject or an archive copy is already restored.

If an archive copy is already restored, the header value indicates when Amazon S3 is scheduled to delete the object copy. For example:

x-amz-restore: ongoing-request="false", expiry-date="Fri, 23 Dec 2012 00:00:00 GMT"

If the object restoration is in progress, the header returns the value ongoing-request="true".

For more information about archiving objects, see Transitioning Objects: General Considerations.

x-amz-server-side-encryption

If the object is stored using server-side encryption either with an AWS KMS or an Amazon S3-managed encryption key, the response includes this header with the value of the Server-side encryption algorithm used when storing this object in S3 (e.g., AES256, aws:kms).

Valid Values: AES256 | aws:kms

x-amz-server-side-encryption-aws-kms-key-id

If present, specifies the ID of the AWS Key Management Service (KMS) master encryption key that was used for the object.

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

If server-side encryption with a customer-provided encryption key was requested, the response will include this header confirming the encryption algorithm used.

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

If server-side encryption with a customer-provided encryption key was requested, the response will include this header to provide round trip message integrity verification of the customer-provided encryption key.

x-amz-storage-class

Provides storage class information of the object. Amazon S3 returns this header for all objects except for Standard storage class objects.

For more information, see Storage Classes.

Valid Values: STANDARD | REDUCED_REDUNDANCY | STANDARD_IA | ONEZONE_IA | INTELLIGENT_TIERING | GLACIER | DEEP_ARCHIVE

x-amz-version-id

Version of the object.

x-amz-website-redirect-location

If the bucket is configured as a website, redirects requests for this object to another object in the same bucket or to an external URL. Amazon S3 stores the value of this header in the object metadata.

Examples

Sample Request

The following request returns the metadata of an object.

HEAD /my-image.jpg HTTP/1.1 Host: bucket.s3.amazonaws.com Date: Wed, 28 Oct 2009 22:32:00 GMT Authorization: AWS AKIAIOSFODNN7EXAMPLE:02236Q3V0RonhpaBX5sCYVf1bNRuU=

Sample Response

Delete the metric configuration with a specified ID, which disables theCloudWatch metrics with the ExampleMetrics value for the FilterId dimension.

HTTP/1.1 200 OK x-amz-id-2: ef8yU9AS1ed4OpIszj7UDNEHGran x-amz-request-id: 318BC8BC143432E5 x-amz-version-id: 3HL4kqtJlcpXroDTDmjVBH40Nrjfkd Date: Wed, 28 Oct 2009 22:32:00 GMT Last-Modified: Sun, 1 Jan 2006 12:00:00 GMT ETag: "fba9dede5f27731c9771645a39863328" Content-Length: 434234 Content-Type: text/plain Connection: close Server: AmazonS3

Sample Response with an expiration tag

If the object is scheduled to expire according to a lifecycle configuration set on the bucket, the response returns the x-amz-expiration tag with information about when Amazon S3 will delete the object. For more information, see Transitioning Objects: General Considerations.

HTTP/1.1 200 OK x-amz-id-2: azQRZtQJ2m1P8R+TIsG9h0VuC/DmiSJmjXUMq7snk+LKSJeurtmfzSlGhR46GzSJ x-amz-request-id: 0EFF61CCE3F24A26 Date: Mon, 17 Dec 2012 02:26:39 GMT Last-Modified: Mon, 17 Dec 2012 02:14:10 GMT x-amz-expiration: expiry-date="Fri, 21 Dec 2012 00:00:00 GMT", rule-id="Rule for testfile.txt" ETag: "54b0c58c7ce9f2a8b551351102ee0938" Accept-Ranges: bytes Content-Type: text/plain Content-Length: 14 Server: AmazonS3

Sample Request Getting Metadata from a Specified Version of an Object

The following request returns the metadata of the specified version of an object.

HEAD /my-image.jpg?versionId=3HL4kqCxf3vjVBH40Nrjfkd HTTP/1.1 Host: bucket.s3.amazonaws.com Date: Wed, 28 Oct 2009 22:32:00 GMT Authorization: AWS AKIAIOSFODNN7EXAMPLE:02236Q3V0WpaBX5sCYVf1bNRuU=

Sample Response to a Versioned HEAD Request

HTTP/1.1 200 OK x-amz-id-2: eftixk72aD6Ap51TnqcoF8epIszj7UDNEHGran x-amz-request-id: 318BC8BC143432E5 x-amz-version-id: 3HL4kqtJlcpXrof3vjVBH40Nrjfkd Date: Wed, 28 Oct 2009 22:32:00 GMT Last-Modified: Sun, 1 Jan 2006 12:00:00 GMT ETag: "fba9dede5f27731c9771645a39863328" Content-Length: 434234 Content-Type: text/plain Connection: close Server: AmazonS3

Sample Request for an Glacier Object

For an archived object, the x-amz-restore header provides the date when the restored copy expires, as shown in the following response. Even if the object is stored in Glacier, all object metadata is still available.

HEAD /my-image.jpg HTTP/1.1 Host: bucket.s3.amazonaws.com Date: 13 Nov 2012 00:28:38 GMT Authorization: AWS AKIAIOSFODNN7EXAMPLE:02236Q3V0RonhpaBX5sCYVf1bNRuU=

Sample Response - Glacier Object

If the object is already restored, the x-amz-restore header provides the date when the restored copy will expire, as shown in the following response.

HTTP/1.1 200 OK x-amz-id-2: FSVaTMjrmBp3Izs1NnwBZeu7M19iI8UbxMbi0A8AirHANJBo+hEftBuiESACOMJp x-amz-request-id: E5CEFCB143EB505A Date: Tue, 13 Nov 2012 00:28:38 GMT Last-Modified: Mon, 15 Oct 2012 21:58:07 GMT x-amz-restore: ongoing-request="false", expiry-date="Wed, 07 Nov 2012 00:00:00 GMT" ETag: "1accb31fcf202eba0c0f41fa2f09b4d7" Accept-Ranges: bytes Content-Type: binary/octet-stream Content-Length: 300 Server: AmazonS3

Sample Response - In-progress restoration

If the restoration is in progress, then the x-amz-restore header returns a message accordingly.

HTTP/1.1 200 OK x-amz-id-2: b+V2mDiMHTdy1myoUBpctvmJl95H9U/OSUm/jRtHxjh0+pCk5SvByL4xu2TDv4GM x-amz-request-id: E2E7B6AEE4E9BD2B Date: Tue, 13 Nov 2012 00:43:32 GMT Last-Modified: Sat, 20 Oct 2012 21:28:27 GMT x-amz-restore: ongoing-request="true" ETag: "1accb31fcf202eba0c0f41fa2f09b4d7" Accept-Ranges: bytes Content-Type: binary/octet-stream Content-Length: 300 Server: AmazonS3

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: