Use CompleteMultipartUpload with an AWS SDK or CLI

//! Complete a multipart upload to an S3 bucket.
/*!
    \param bucket: The name of the S3 bucket where the object will be uploaded.
    \param key: The unique identifier (key) for the object within the S3 bucket.
    \param uploadID: An upload ID string.
    \param parts: A vector of CompleteParts.
    \param client: The S3 client instance used to perform the upload operation.
    \return CompleteMultipartUploadOutcome: The request outcome.
*/
Aws::S3::Model::CompleteMultipartUploadOutcome AwsDoc::S3::completeMultipartUpload(const Aws::String &bucket,
                                                                                   const Aws::String &key,
                                                                                   const Aws::String &uploadID,
                                                                                   const Aws::Vector<Aws::S3::Model::CompletedPart> &parts,
                                                                                   const Aws::S3::S3Client &client) {
    Aws::S3::Model::CompletedMultipartUpload completedMultipartUpload;
    completedMultipartUpload.SetParts(parts);

    Aws::S3::Model::CompleteMultipartUploadRequest request;
    request.SetBucket(bucket);
    request.SetKey(key);
    request.SetUploadId(uploadID);
    request.SetMultipartUpload(completedMultipartUpload);

    Aws::S3::Model::CompleteMultipartUploadOutcome outcome =
            client.CompleteMultipartUpload(request);

    if (!outcome.IsSuccess()) {
        std::cerr << "Error completing multipart upload: " << outcome.GetError().GetMessage() << std::endl;
    }
    return outcome;
}

The following command completes a multipart upload for the key multipart/01 in the bucket amzn-s3-demo-bucket:

aws s3api complete-multipart-upload --multipart-upload file://mpustruct --bucket amzn-s3-demo-bucket --key 'multipart/01' --upload-id dfRtDYU0WWCCcH43C3WFbkRONycyCpTJJvxu2i5GYkZljF.Yxwh6XG7WfS2vC4to6HiV6Yjlx.cph0gtNBtJ8P3URCSbB7rjxI5iEwVDmgaXZOGgkk5nVTW16HOQ5l0R

The upload ID required by this command is output by create-multipart-upload and can also be retrieved with list-multipart-uploads.

The multipart upload option in the above command takes a JSON structure that describes the parts of the multipart upload that should be reassembled into the complete file. In this example, the file:// prefix is used to load the JSON structure from a file in the local folder named mpustruct.

mpustruct:

{
  "Parts": [
    {
      "ETag": "e868e0f4719e394144ef36531ee6824c",
      "PartNumber": 1
    },
    {
      "ETag": "6bb2b12753d66fe86da4998aa33fffb0",
      "PartNumber": 2
    },
    {
      "ETag": "d0a0112e841abec9c9ec83406f0159c8",
      "PartNumber": 3
    }
  ]
}

The ETag value for each part is upload is output each time you upload a part using the upload-part command and can also be retrieved by calling list-parts or calculated by taking the MD5 checksum of each part.

Output:

{
    "ETag": "\"3944a9f7a4faab7f78788ff6210f63f0-3\"",
    "Bucket": "amzn-s3-demo-bucket",
    "Location": "https://amzn-s3-demo-bucket.s3.amazonaws.com/multipart%2F01",
    "Key": "multipart/01"
}

    // upload_parts: Vec<aws_sdk_s3::types::CompletedPart>
    let completed_multipart_upload: CompletedMultipartUpload = CompletedMultipartUpload::builder()
        .set_parts(Some(upload_parts))
        .build();

    let _complete_multipart_upload_res = client
        .complete_multipart_upload()
        .bucket(&bucket_name)
        .key(&key)
        .multipart_upload(completed_multipart_upload)
        .upload_id(upload_id)
        .send()
        .await?;

    // Create a multipart upload. Use UploadPart and CompleteMultipartUpload to
    // upload the file.
    let multipart_upload_res: CreateMultipartUploadOutput = client
        .create_multipart_upload()
        .bucket(&bucket_name)
        .key(&key)
        .send()
        .await?;

    let upload_id = multipart_upload_res.upload_id().ok_or(S3ExampleError::new(
        "Missing upload_id after CreateMultipartUpload",
    ))?;

    let mut upload_parts: Vec<aws_sdk_s3::types::CompletedPart> = Vec::new();

    for chunk_index in 0..chunk_count {
        let this_chunk = if chunk_count - 1 == chunk_index {
            size_of_last_chunk
        } else {
            CHUNK_SIZE
        };
        let stream = ByteStream::read_from()
            .path(path)
            .offset(chunk_index * CHUNK_SIZE)
            .length(Length::Exact(this_chunk))
            .build()
            .await
            .unwrap();

        // Chunk index needs to start at 0, but part numbers start at 1.
        let part_number = (chunk_index as i32) + 1;
        let upload_part_res = client
            .upload_part()
            .key(&key)
            .bucket(&bucket_name)
            .upload_id(upload_id)
            .body(stream)
            .part_number(part_number)
            .send()
            .await?;

        upload_parts.push(
            CompletedPart::builder()
                .e_tag(upload_part_res.e_tag.unwrap_or_default())
                .part_number(part_number)
                .build(),
        );
    }