s3_head_object: The HEAD operation retrieves metadata from an object without...

Description Usage Arguments Value Request syntax Examples

View source: R/s3_operations.R

Description

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:

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 CMKs stored in AWS KMS (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:

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.

The following operation is related to head_object:

Usage

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s3_head_object(Bucket, IfMatch, IfModifiedSince, IfNoneMatch,
  IfUnmodifiedSince, Key, Range, VersionId, SSECustomerAlgorithm,
  SSECustomerKey, SSECustomerKeyMD5, RequestPayer, PartNumber,
  ExpectedBucketOwner)

Arguments

Bucket

[required] The name of the bucket containing the object.

When using this API with an access point, 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 operation with an access point through the AWS 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 Simple Storage Service Developer Guide.

When using this API 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 using this operation using S3 on Outposts through the AWS SDKs, you provide the Outposts bucket ARN in place of the bucket name. For more information about S3 on Outposts ARNs, see Using S3 on Outposts in the Amazon Simple Storage Service Developer Guide.

IfMatch

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

IfModifiedSince

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

IfNoneMatch

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

IfUnmodifiedSince

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

Key

[required] The object key.

Range

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

Amazon S3 doesn't support retrieving multiple ranges of data per GET request.

VersionId

VersionId used to reference a specific version of the object.

SSECustomerAlgorithm

Specifies the algorithm to use to when encrypting the object (for example, AES256).

SSECustomerKey

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 S3 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.

SSECustomerKeyMD5

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 that the encryption key was transmitted without error.

RequestPayer
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.

ExpectedBucketOwner

The account id of the expected bucket owner. If the bucket is owned by a different account, the request will fail with an HTTP 403 (Access Denied) error.

Value

A list with the following syntax:

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list(
  DeleteMarker = TRUE|FALSE,
  AcceptRanges = "string",
  Expiration = "string",
  Restore = "string",
  ArchiveStatus = "ARCHIVE_ACCESS"|"DEEP_ARCHIVE_ACCESS",
  LastModified = as.POSIXct(
    "2015-01-01"
  ),
  ContentLength = 123,
  ETag = "string",
  MissingMeta = 123,
  VersionId = "string",
  CacheControl = "string",
  ContentDisposition = "string",
  ContentEncoding = "string",
  ContentLanguage = "string",
  ContentType = "string",
  Expires = as.POSIXct(
    "2015-01-01"
  ),
  WebsiteRedirectLocation = "string",
  ServerSideEncryption = "AES256"|"aws:kms",
  Metadata = list(
    "string"
  ),
  SSECustomerAlgorithm = "string",
  SSECustomerKeyMD5 = "string",
  SSEKMSKeyId = "string",
  BucketKeyEnabled = TRUE|FALSE,
  StorageClass = "STANDARD"|"REDUCED_REDUNDANCY"|"STANDARD_IA"|"ONEZONE_IA"|"INTELLIGENT_TIERING"|"GLACIER"|"DEEP_ARCHIVE"|"OUTPOSTS",
  RequestCharged = "requester",
  ReplicationStatus = "COMPLETE"|"PENDING"|"FAILED"|"REPLICA",
  PartsCount = 123,
  ObjectLockMode = "GOVERNANCE"|"COMPLIANCE",
  ObjectLockRetainUntilDate = as.POSIXct(
    "2015-01-01"
  ),
  ObjectLockLegalHoldStatus = "ON"|"OFF"
)

Request syntax

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svc$head_object(
  Bucket = "string",
  IfMatch = "string",
  IfModifiedSince = as.POSIXct(
    "2015-01-01"
  ),
  IfNoneMatch = "string",
  IfUnmodifiedSince = as.POSIXct(
    "2015-01-01"
  ),
  Key = "string",
  Range = "string",
  VersionId = "string",
  SSECustomerAlgorithm = "string",
  SSECustomerKey = raw,
  SSECustomerKeyMD5 = "string",
  RequestPayer = "requester",
  PartNumber = 123,
  ExpectedBucketOwner = "string"
)

Examples

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## Not run: 
# The following example retrieves an object metadata.
svc$head_object(
  Bucket = "examplebucket",
  Key = "HappyFace.jpg"
)

## End(Not run)

paws.storage documentation built on March 7, 2021, 5:07 p.m.