IAmazonS3.InitiateMultipartUploadAsync (InitiateMultipartUploadRequest, CancellationToken)

Method

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.

Request signing

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.

Permissions

• General purpose bucket permissions - To perform a multipart upload with encryption using an Key Management Service (KMS) KMS key, the requester must have permission to the kms:Decrypt and kms:GenerateDataKey actions on the key. The requester must also have permissions for the kms:GenerateDataKey action for the CreateMultipartUpload API. Then, the requester needs permissions for the kms:Decrypt action on the UploadPart and UploadPartCopy APIs. 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.

Encryption

• 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, there are only two supported options for server-side encryption: server-side encryption with Amazon S3 managed keys (SSE-S3) (AES256) and server-side encryption with KMS keys (SSE-KMS) (aws:kms). We recommend that the bucket's default encryption uses the desired encryption configuration and you don't override the bucket default encryption in your CreateSession requests or PUT object requests. Then, new objects are automatically encrypted with the desired encryption settings. For more information, see Protecting data with server-side encryption in the Amazon S3 User Guide. For more information about the encryption overriding behaviors in directory buckets, see Specifying server-side encryption with KMS for new object uploads.

  In the Zonal endpoint API calls (except CopyObject and UploadPartCopy) using the REST API, the encryption request headers must match the encryption settings that are specified in the CreateSession request. You can't override the values of the encryption settings (x-amz-server-side-encryption, x-amz-server-side-encryption-aws-kms-key-id, x-amz-server-side-encryption-context, and x-amz-server-side-encryption-bucket-key-enabled) that are specified in the CreateSession request. You don't need to explicitly specify these encryption settings values in Zonal endpoint API calls, and Amazon S3 will use the encryption settings values from the CreateSession request to protect new objects in the directory bucket.

  When you use the CLI or the Amazon Web Services SDKs, for CreateSession, the session token refreshes automatically to avoid service interruptions when a session expires. The CLI or the Amazon Web Services SDKs use the bucket's default encryption configuration for the CreateSession request. It's not supported to override the encryption settings values in the CreateSession request. So in the Zonal endpoint API calls (except CopyObject and UploadPartCopy), the encryption request headers must match the default encryption configuration of the directory bucket.

  For directory buckets, when you perform a CreateMultipartUpload operation and an UploadPartCopy operation, the request headers you provide in the CreateMultipartUpload request must match the default encryption configuration of the destination bucket.

HTTP Host header syntax

Directory buckets - The HTTP Host header syntax is Bucket-name.s3express-zone-id.region-code.amazonaws.com.

The following operations are related to CreateMultipartUpload:

• UploadPart

• CompleteMultipartUpload

• AbortMultipartUpload

• ListParts

• ListMultipartUploads

Namespace: Amazon.S3
Assembly: AWSSDK.S3.dll
Version: 3.x.y.z