如何使用ruby更新一批S3對象的元數據？

Question

我需要在S3上更改數百或數千個對象上的某些元數據（Content-Type）。用ruby做這件事的好方法是什麼？據我所知，沒有辦法只保存與fog.io元數據，整個對象必須重新保存。似乎使用the official sdk library將需要我爲這一個任務滾動一個包裝環境。

Answer 1

你是對的，官方的SDK可以讓你修改的對象元數據而無需重新上傳。它的功能是copy the object，但這是在服務器上，所以你不需要下載文件並重新上傳。

一個包裝很容易實現，像

bucket.objects.each do |object| 
    object.metadata['content-type'] = 'application/json' 
end 

Answer 2

對於未來的讀者，這是一個使用Ruby的AWS-SDK V1改變的東西的一個完整樣本（另見本Gist的AWS-SDK V2樣品）：

# Using v1 of Ruby aws-sdk as currently v2 seems not able to do this (broken?). 
require 'aws-sdk-v1' 

key = YOUR_AWS_KEY 
secret = YOUR_AWS_SECRET 
region = YOUR_AWS_REGION 

AWS.config(access_key_id: key, secret_access_key: secret, region: region) 
s3 = AWS::S3.new 
bucket = s3.buckets[bucket_name] 
bucket.objects.with_prefix('images/').each do |obj| 
    puts obj.key 
    # Add metadata: {} to next line for more metadata. 
    obj.copy_from(obj.key, content_type: obj.content_type, cache_control: 'max-age=1576800000', acl: :public_read) 
end 

Answer 3

在V2 API，你可以使用Object#copy_from()或Object.copy_to()與:metadata和:metadata_directive => 'REPLACE'選項，而從S3下載該更新對象的元數據。

在Joost's gist的代碼引發此錯誤：

Aws::S3::Errors::InvalidRequest: This copy request is illegal because it is trying to copy an object to itself without changing the object's metadata, storage class, website redirect location or encryption attributes.

這是因爲通過默認AWS忽略與複製操作，因爲它複製的元數據提供的:metadata。如果我們想更新元數據，我們必須設置:metadata_directive => 'REPLACE'選項。

見http://docs.aws.amazon.com/sdkforruby/api/Aws/S3/Object.html#copy_from-instance_method

下面是我最近使用進行元數據更新操作全，工作代碼片段：

require 'aws-sdk' 

# S3 setup boilerplate 
client = Aws::S3::Client.new(
    :region => 'us-east-1', 
    :access_key_id => ENV['AWS_ACCESS_KEY'], 
    :secret_access_key => ENV['AWS_SECRET_KEY'], 
) 
s3 = Aws::S3::Resource.new(:client => client) 

# Get an object reference 
object = s3.bucket('my-bucket-name').object('my-object/key') 

# Create our new metadata hash. This can be any hash; in this example we update 
# existing metadata with a new key-value pair. 
new_metadata = object.metadata.merge('MY_NEW_KEY' => 'MY_NEW_VALUE') 

# Use the copy operation to replace our metadata 
object.copy_to(object, 
    :metadata => new_metadata, 

    # IMPORTANT: normally S3 copies the metadata along with the object. 
    # we must supply this directive to replace the existing metadata with 
    # the values we supply 
    :metadata_directive => "REPLACE", 
) 

爲了便於再利用：

def update_metadata(s3_object, new_metadata = {}) 
    s3_object.copy_to(s3_object, 
    :metadata => new_metadata 
    :metadata_directive => "REPLACE" 
) 
end 

Answer 4

一些搜索後這似乎爲我

obj.copy_to(obj, :metadata_directive=>"REPLACE", :acl=>"public-read",:content_type=>"text/plain") 

工作