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.
s3_head_object(Bucket, IfMatch, IfModifiedSince, IfNoneMatch,
IfUnmodifiedSince, Key, Range, VersionId, SSECustomerAlgorithm,
SSECustomerKey, SSECustomerKeyMD5, RequestPayer, PartNumber)[required] The name of the bucket containing the object.
Return the object only if its entity tag (ETag) is the same as the one specified, otherwise return a 412 (precondition failed).
Return the object only if it has been modified since the specified time, otherwise return a 304 (not modified).
Return the object only if its entity tag (ETag) is different from the one specified, otherwise return a 304 (not modified).
Return the object only if it has not been modified since the specified time, otherwise return a 412 (precondition failed).
[required] The object key.
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.
VersionId used to reference a specific version of the object.
Specifies the algorithm to use to when encrypting the object (for example, AES256).
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<U+00E2><U+20AC><U+2039>-encryption<U+00E2><U+20AC><U+2039>-customer-algorithm header.
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.
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.
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
)
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<U+00E2><U+20AC><U+2039>-encryption<U+00E2><U+20AC><U+2039>-customer-algorithm
x-amz-server-side<U+00E2><U+20AC><U+2039>-encryption<U+00E2><U+20AC><U+2039>-customer-key
x-amz-server-side<U+00E2><U+20AC><U+2039>-encryption<U+00E2><U+20AC><U+2039>-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 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:
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
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 operation is related to HeadObject:
GetObject
# NOT RUN {
# The following example retrieves an object metadata.
# }
# NOT RUN {
svc$head_object(
Bucket = "examplebucket",
Key = "HappyFace.jpg"
)
# }
# NOT RUN {
# }
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