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This action initiates a multipart upload and returns an upload ID. This upload ID
is used to associate all of the parts in the specific multipart upload. You specify
this upload ID in each of your subsequent upload part requests (see UploadPart).
You also include this upload ID in the final request to either complete or abort the
multipart upload request. For more information about multipart uploads, see Multipart
Upload Overview in the Amazon S3 User Guide.
After you initiate a multipart upload and upload one or more parts, to stop being
charged for storing the uploaded parts, you must either complete or abort the multipart
upload. Amazon S3 frees up the space used to store the parts and stops charging you
for storing them only after you either complete or abort a multipart upload.
If you have configured a lifecycle rule to abort incomplete multipart uploads, the created multipart upload must be completed within the number of days specified in the bucket lifecycle configuration. Otherwise, the incomplete multipart upload becomes eligible for an abort action and Amazon S3 aborts the multipart upload. For more information, see Aborting Incomplete Multipart Uploads Using a Bucket Lifecycle Configuration.
Directory buckets - S3 Lifecycle is not supported by directory buckets.
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.
For request signing, multipart upload is just a series of regular requests. You initiate a multipart upload, send one or more requests to upload parts, and then complete the multipart upload process. You sign each request individually. There is nothing special about signing multipart upload requests. For more information about signing, see Authenticating Requests (Amazon Web Services Signature Version 4) in the Amazon S3 User Guide.
General purpose bucket permissions - For information about the permissions required to use the multipart upload API, see Multipart upload and permissions in the Amazon S3 User Guide.
To perform a multipart upload with encryption by using an Amazon Web Services KMS
key, the requester must have permission to the kms:Decrypt and kms:GenerateDataKey*
actions on the key. These permissions are required because Amazon S3 must decrypt
and read data from the encrypted file parts before it completes the multipart upload.
For more information, see Multipart
upload API and permissions and Protecting
data using server-side encryption with Amazon Web Services KMS in the Amazon
S3 User Guide.
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.
General purpose buckets - Server-side encryption is for data encryption at
rest. Amazon S3 encrypts your data as it writes it to disks in its data centers and
decrypts it when you access it. Amazon S3 automatically encrypts all new objects that
are uploaded to an S3 bucket. When doing a multipart upload, if you don't specify
encryption information in your request, the encryption setting of the uploaded parts
is set to the default encryption configuration of the destination bucket. By default,
all buckets have a base level of encryption configuration that uses server-side encryption
with Amazon S3 managed keys (SSE-S3). If the destination bucket has a default encryption
configuration that uses server-side encryption with an Key Management Service (KMS)
key (SSE-KMS), or a customer-provided encryption key (SSE-C), Amazon S3 uses the corresponding
KMS key, or a customer-provided key to encrypt the uploaded parts. When you perform
a CreateMultipartUpload operation, if you want to use a different type of encryption
setting for the uploaded parts, you can request that Amazon S3 encrypts the object
with a different encryption key (such as an Amazon S3 managed key, a KMS key, or a
customer-provided key). When the encryption setting in your request is different from
the default encryption configuration of the destination bucket, the encryption setting
in your request takes precedence. If you choose to provide your own encryption key,
the request headers you provide in UploadPart
and UploadPartCopy
requests must match the headers you used in the CreateMultipartUpload request.
Use KMS keys (SSE-KMS) that include the Amazon Web Services managed key (aws/s3)
and KMS customer managed keys stored in Key Management Service (KMS) – If you want
Amazon Web Services to manage the keys used to encrypt data, specify the following
headers in the request.
x-amz-server-side-encryption
x-amz-server-side-encryption-aws-kms-key-id
x-amz-server-side-encryption-context
If you specify x-amz-server-side-encryption:aws:kms, but don't provide x-amz-server-side-encryption-aws-kms-key-id,
Amazon S3 uses the Amazon Web Services managed key (aws/s3 key) in KMS to protect
the data.
To perform a multipart upload with encryption by using an Amazon Web Services KMS
key, the requester must have permission to the kms:Decrypt and kms:GenerateDataKey*
actions on the key. These permissions are required because Amazon S3 must decrypt
and read data from the encrypted file parts before it completes the multipart upload.
For more information, see Multipart
upload API and permissions and Protecting
data using server-side encryption with Amazon Web Services KMS in the Amazon
S3 User Guide.
If your Identity and Access Management (IAM) user or role is in the same Amazon Web Services account as the KMS key, then you must have these permissions on the key policy. If your IAM user or role is in a different account from the key, then you must have the permissions on both the key policy and your IAM user or role.
All GET and PUT requests for an object protected by KMS fail if you
don't make them by using Secure Sockets Layer (SSL), Transport Layer Security (TLS),
or Signature Version 4. For information about configuring any of the officially supported
Amazon Web Services SDKs and Amazon Web Services CLI, see Specifying
the Signature Version in Request Authentication in the Amazon S3 User Guide.
For more information about server-side encryption with KMS keys (SSE-KMS), see Protecting Data Using Server-Side Encryption with KMS keys in the Amazon S3 User Guide.
Use customer-provided encryption keys (SSE-C) – If you want to manage your own encryption keys, provide all the following headers in the request.
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 server-side encryption with customer-provided encryption keys (SSE-C), see Protecting data using server-side encryption with customer-provided encryption keys (SSE-C) in the Amazon S3 User Guide.
Directory buckets -For directory buckets, only server-side encryption with
Amazon S3 managed keys (SSE-S3) (AES256) is supported.
Directory buckets - The HTTP Host header syntax is Bucket_name.s3express-az_id.region.amazonaws.com.
The following operations are related to CreateMultipartUpload:
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 BeginInitiateMultipartUpload and EndInitiateMultipartUpload.
Namespace: Amazon.S3
Assembly: AWSSDK.S3.dll
Version: 3.x.y.z
public abstract Task<InitiateMultipartUploadResponse> InitiateMultipartUploadAsync( String bucketName, String key, CancellationToken cancellationToken )
The name of the bucket where the multipart upload is initiated and where the object is uploaded. 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.
Object key for which the multipart upload is to be initiated.
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