Question

我打算在IBM Bluemix中使用S3 Cloudstorage，但后来我发现一件奇怪的事情就是无法将自定义META-DATA添加到存储在S3存储桶中的对象。

有没有办法可以将自定义元数据添加到对象中，如果是，那么请告知我们如何添加和访问它。

Answer 1

感谢您在文档中指出一个漏洞！

通过传递x-amz-meta-{key}标头{value}来定义自定义元数据。作为示例请求：

PUT /{bucket-name}/{object-name} HTTP/1.1
Authorization: {authorization-string}
x-amz-meta-foo: bar
x-amz-date: 20160825T183001Z
x-amz-content-sha256:{hashed-body}
Content-Type: text/plain; charset=utf-8
Host: s3-api.us-geo.objectstorage.softlayer.net
Content-Length: 18

{
  "foo": "bar"
}

检查元数据的HEAD请求如下所示：

HEAD /{bucket-name}/{object-name} HTTP/1.1
Authorization: {authorization-string}
x-amz-date: 20160825T183244Z
Host: s3-api.us-geo.objectstorage.softlayer.net

并回复：

HTTP/1.1 200 OK
Date: Thu, 25 Aug 2016 18:32:44 GMT
X-Clv-Request-Id: da214d69-1999-4461-a130-81ba33c484a6
Accept-Ranges: bytes
Server: Cleversafe/3.9.1.102
X-Clv-S3-Version: 2.5
ETag: {MD5-hash}
Content-Type: text/plain; charset=UTF-8
x-amz-meta-foo: bar
Last-Modified: Thu, 25 Aug 2016 17:49:06 GMT
Content-Length: 18

使用CLI，语法为：

$ aws --endpoint-url=https://{endpoint} s3 cp ~/new-file s3://bucket-1/ --metadata foo=bar

希望有所帮助！

Answer 2

这是可能的。我每天都在使用它。添加元数据，然后通过执行cron调用在数据库中发送元数据。以下是为列表对象创建/添加/更改元数据的python脚本的一个小示例：

import sys
import os 
import boto3
import pprint
from boto3 import client
from botocore.utils import fix_s3_host

param_1= YOUR_ACCESS_KEY
param_2= YOUR_SECRETE_KEY
param_3= YOUR_END_POINT 
param_4= YOUR_BUCKET

#Create the S3 client
s3ressource = client(
    service_name='s3', 
    endpoint_url= param_3,
    aws_access_key_id= param_1,
    aws_secret_access_key=param_2,
    use_ssl=True,
    )
# Building a list  of object per bucket
def BuildObjectListPerBucket (variablebucket):
    global listofObjectstobeanalyzed
    listofObjectstobeanalyzed = []
    extensions = ['.jpg','.png']
    for key  in s3ressource.list_objects(Bucket=variablebucket)["Contents"]:
        #print (key ['Key'])
        onemoreObject=key['Key']
        if onemoreObject.endswith(tuple(extensions)):
            listofObjectstobeanalyzed.append(onemoreObject)

        else :
            s3ressource.delete_object(Bucket=variablebucket,Key=onemoreObject)          
    return listofObjectstobeanalyzed

# for a given existing object, create metadata
def createmetdata(bucketname,objectname):
    s3ressource.upload_file(objectname, bucketname, objectname, ExtraArgs={"Metadata": {"metadata1":"ImageName","metadata2":"ImagePROPERTIES" ,"metadata3":"ImageCREATIONDATE"}})

# for a given existing object, add new metadata
def ADDmetadata(bucketname,objectname):
    s3_object = s3ressource.get_object(Bucket=bucketname, Key=objectname)
    k = s3ressource.head_object(Bucket = bucketname, Key = objectname)
    m = k["Metadata"]
    m["new_metadata"] = "ImageNEWMETADATA"
    s3ressource.copy_object(Bucket = bucketname, Key = objectname, CopySource = bucketname + '/' + objectname, Metadata = m, MetadataDirective='REPLACE')

# for a given existing object, update  a metadata with new value
def CHANGEmetadata(bucketname,objectname):
    s3_object = s3ressource.get_object(Bucket=bucketname, Key=objectname)
    k = s3ressource.head_object(Bucket = bucketname, Key = objectname)
    m = k["Metadata"]
    m.update({'watson_visual_rec_dic':'ImageCREATIONDATEEEEEEEEEEEEEEEEEEEEEEEEEE'})
    s3ressource.copy_object(Bucket = bucketname, Key = objectname, CopySource = bucketname + '/' + objectname, Metadata = m, MetadataDirective='REPLACE')

def readmetadata (bucketname,objectname):
    ALLDATAOFOBJECT = s3ressource.get_object(Bucket=bucketname, Key=objectname)
    ALLDATAOFOBJECTMETADATA=ALLDATAOFOBJECT['Metadata']
    print ALLDATAOFOBJECTMETADATA



# create the list of object on a per bucket basis

BuildObjectListPerBucket (variablebucket)

# Call functions to see the results 

for objectitem in listofObjectstobeanalyzed:
    readmetadata(param_4,objectitem)
    createmetdata(param_4,objectitem)
    readmetadata(param_4,objectitem)
    ADDmetadata(param_4,objectitem)
    readmetadata(param_4,objectitem)
    CHANGEmetadata(param_4,objectitem)
    readmetadata(param_4,objectitem)

在IBM Bluemix上使用S3云存储

2 个答案: