使用移动客户端的查询参数获取S3预先分配的帖子URL

Question

我正在使用Rails 4为后端服务创建API.该服务需要将图像文件上传到amazon s3存储桶.

我想使用直接上传网址,以便客户端管理上传到s3,服务器不会保持忙碌状态.

目前我有以下原型导轨动作

def create
  filename = params[:filename]
  s3_direct_post = S3_BUCKET.presigned_post(key: "offers/#{SecureRandom.uuid}/#{filename}", acl: 'public-read')
  s3p = s3_direct_post.fields
  url = "#{s3_direct_post.url}/#{filename}?X-Amz-Algorithm=#{s3p['x-amz-algorithm']}&X-Amz-Credential=#{s3p['x-amz-credential']}&X-Amz-Date=#{s3p['x-amz-date']}&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=#{s3p['x-amz-signature']}"
  render json: {success: true, url: url}, status: :ok
end

这会生成这样的网址:

https://my-bucket.s3.eu-central-1.amazonaws.com/test.png?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=MYKEY/20150420/eu-central-1/s3/aws4_request&X-Amz-Date=20150420T162603Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=MYSIGNATURE

现在我尝试使用以下内容将test.png发布到此URL:

curl -v -T test.png "url"

我收到以下错误响应:

<Error><Code>SignatureDoesNotMatch</Code><Message>The request signature we calculated does not match the signature you provided. Check your key and signing method.</Message><AWSAccessKeyId>MYKEY</AWSAccessKeyId>...

我认为问题来自于指定的X-Amz-SignedHeaders标头错误.我不确定默认情况下从amazon rails sdk gem使用哪些头文件.

我应该如何更改我的网址生成,以便移动客户端可以只获取网址并将文件发布到该网址？

Answer 1

这是一个解决方案:

在config/initializers/aws.rb:

AWS_CREDS = Aws::Credentials.new(ENV['AWS_ACCESS_KEY_ID'], ENV['AWS_SECRET_ACCESS_KEY'])

Aws.config.update({
  region: 'eu-central-1',
  credentials: AWS_CREDS
})

S3 = Aws::S3::Resource.new('eu-central-1')
S3_BUCKET_NAME = ENV['S3_BUCKET_NAME']
S3_BUCKET = S3.bucket(S3_BUCKET_NAME)

在你的模型/控制器/关注/或其他:

obj = S3_BUCKET.object("offers/#{user.id}/#{self.id}")
url = obj.presigned_url(:put) # obj.presigned_url(:put, acl: 'public-read') #if you want to make the file public

然后上传你可以使用移动客户端或卷曲:

curl -X PUT -T file_to_upload "url from above"

请注意,x-amz-acl: public-read如果使用public-readacl选项,则必须添加标头:

curl -H "x-amz-acl: public-read" -X PUT -T file_to_upload "url from above"