Amazon S3 连接小文件

Question

有没有办法在 Amazon S3 上连接小于 5MB 的小文件。 由于文件小，不能进行多部分上传。

下拉所有这些文件并进行连接并不是一个有效的解决方案。

那么，谁能告诉我一些 API 来做这些？

Answer 1

Amazon S3 不提供连接功能。它主要是一种对象存储服务。

您将需要一些过程来下载对象、组合它们，然后再次上传它们。最有效的方法是并行下载对象，以充分利用可用带宽。但是，这对代码来说更复杂。

我建议在“云中”进行处理，以避免必须通过 Internet 下载对象。在 Amazon EC2 或 AWS Lambda 上执行此操作会更高效且成本更低。

Answer 2

编辑：没有看到 5MB 的要求。由于此要求，此方法将不起作用。

来自https://ruby.awsblog.com/post/Tx2JE2CXGQGQ6A4/Efficient-Amazon-S3-Object-Concatenation-Using-the-AWS-SDK-for-Ruby：

虽然可以通过以下方式将数据下载并重新上传到 S3 一个 EC2 实例，更有效的方法是指示 S3 使用新的 copy_part API 操作制作内部副本 在 1.10.0 版中引入了 Ruby SDK。

代码：

require 'rubygems'
require 'aws-sdk'

s3 = AWS::S3.new()
mybucket = s3.buckets['my-multipart']

# First, let's start the Multipart Upload
obj_aggregate = mybucket.objects['aggregate'].multipart_upload

# Then we will copy into the Multipart Upload all of the objects in a certain S3 directory.
mybucket.objects.with_prefix('parts/').each do |source_object|

  # Skip the directory object
  unless (source_object.key == 'parts/')
    # Note that this section is thread-safe and could greatly benefit from parallel execution.
    obj_aggregate.copy_part(source_object.bucket.name + '/' + source_object.key)
  end

end

obj_completed = obj_aggregate.complete()

# Generate a signed URL to enable a trusted browser to access the new object without authenticating.
puts obj_completed.url_for(:read)

限制（除其他外）

• 除最后一部分外，最小部分大小为 5 MB。
• 已完成的分段上传对象的最大大小限制为 5 TB。

Answer 3

根据@wwadge 的评论，我编写了一个 Python 脚本。

它通过上传一个略大于 5MB 的虚拟对象来绕过 5MB 限制，然后将每个小文件附加到最后一个文件中。最后，它会从合并的文件中删除虚拟部分。

import boto3
import os

bucket_name = 'multipart-bucket'
merged_key = 'merged.json'
mini_file_0 = 'base_0.json'
mini_file_1 = 'base_1.json'
dummy_file = 'dummy_file'

s3_client = boto3.client('s3')
s3_resource = boto3.resource('s3')

# we need to have a garbage/dummy file with size > 5MB
# so we create and upload this
# this key will also be the key of final merged file
with open(dummy_file, 'wb') as f:
    # slightly > 5MB
    f.seek(1024 * 5200) 
    f.write(b'0')

with open(dummy_file, 'rb') as f:
    s3_client.upload_fileobj(f, bucket_name, merged_key)

os.remove(dummy_file)


# get the number of bytes of the garbage/dummy-file
# needed to strip out these garbage/dummy bytes from the final merged file
bytes_garbage = s3_resource.Object(bucket_name, merged_key).content_length

# for each small file you want to concat
# when this loop have finished merged.json will contain 
# (merged.json + base_0.json + base_2.json)
for key_mini_file in ['base_0.json','base_1.json']: # include more files if you want

    # initiate multipart upload with merged.json object as target
    mpu = s3_client.create_multipart_upload(Bucket=bucket_name, Key=merged_key)
        
    part_responses = []
    # perform multipart copy where merged.json is the first part 
    # and the small file is the second part
    for n, copy_key in enumerate([merged_key, key_mini_file]):
        part_number = n + 1
        copy_response = s3_client.upload_part_copy(
            Bucket=bucket_name,
            CopySource={'Bucket': bucket_name, 'Key': copy_key},
            Key=merged_key,
            PartNumber=part_number,
            UploadId=mpu['UploadId']
        )

        part_responses.append(
            {'ETag':copy_response['CopyPartResult']['ETag'], 'PartNumber':part_number}
        )

    # complete the multipart upload
    # content of merged will now be merged.json + mini file
    response = s3_client.complete_multipart_upload(
        Bucket=bucket_name,
        Key=merged_key,
        MultipartUpload={'Parts': part_responses},
        UploadId=mpu['UploadId']
    )

# get the number of bytes from the final merged file
bytes_merged = s3_resource.Object(bucket_name, merged_key).content_length

# initiate a new multipart upload
mpu = s3_client.create_multipart_upload(Bucket=bucket_name, Key=merged_key)            
# do a single copy from the merged file specifying byte range where the 
# dummy/garbage bytes are excluded
response = s3_client.upload_part_copy(
    Bucket=bucket_name,
    CopySource={'Bucket': bucket_name, 'Key': merged_key},
    Key=merged_key,
    PartNumber=1,
    UploadId=mpu['UploadId'],
    CopySourceRange='bytes={}-{}'.format(bytes_garbage, bytes_merged-1)
)
# complete the multipart upload
# after this step the merged.json will contain (base_0.json + base_2.json)
response = s3_client.complete_multipart_upload(
    Bucket=bucket_name,
    Key=merged_key,
    MultipartUpload={'Parts': [
       {'ETag':response['CopyPartResult']['ETag'], 'PartNumber':1}
    ]},
    UploadId=mpu['UploadId']
)

如果您已经有一个 >5MB 的对象还想添加更小的部分，那么请跳过创建虚拟文件和最后一个带有字节范围的副本部分。另外，我不知道这对大量非常小的文件如何执行 - 在这种情况下，最好下载每个文件，在本地合并它们然后上传。