<p>你说得对,要建立这个系统需要大量的API工作。我希望他们很快就能在AWS控制台上找到它!</p>
<p><strong>更新:我已将此代码提交给boto—从boto v2.1(2011-10-27发布)开始,这变得容易多了。对于boto<;2.1,请使用此处的说明。对于boto 2.1或更高版本,请在我的博客上获取更新说明:<a href="http://www.secretmike.com/2011/10/aws-cloudfront-secure-streaming.html" rel="noreferrer">http://www.secretmike.com/2011/10/aws-cloudfront-secure-streaming.html</a>一旦boto 2.1被更多发行版打包,我将在此处更新答案。</strong></p>
<p>为了实现您的目标,您需要执行以下步骤,我将在下面详细介绍:</p>
<ol>
<li>创建s3 bucket并上传一些对象(您已经完成了此操作)</li>
<li>创建一个Cloudfront“Origin Access Identity”(基本上是一个AWS帐户,允许Cloudfront访问您的s3 bucket)</li>
<li>修改对象上的acl,以便只允许您的Cloudfront源访问标识读取它们(这可以防止人们绕过Cloudfront直接进入s3)</li>
<li>使用基本url和需要签名url的url创建cloudfront分发</li>
<li>测试是否可以从基本cloudfront发行版下载对象,但不能从s3或签名的cloudfront发行版下载对象</li>
<li>创建用于签名URL的密钥对</li>
<li>使用Python生成一些url</li>
<li>测试签名的url是否工作</li>
</ol>
<hr/>
<p><strong>1-创建Bucket并上载对象</p>
<p>最简单的方法是通过AWS控制台,但为了完整起见,我将展示如何使用boto。Boto代码如下所示:</p>
<pre><code>import boto
#credentials stored in environment AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
s3 = boto.connect_s3()
#bucket name MUST follow dns guidelines
new_bucket_name = "stream.example.com"
bucket = s3.create_bucket(new_bucket_name)
object_name = "video.mp4"
key = bucket.new_key(object_name)
key.set_contents_from_filename(object_name)
</code></pre>
<p><strong>2-创建Cloudfront“源访问标识”</strong></p>
<p>目前,此步骤只能使用API执行。僵尸代码在这里:</p>
<pre><code>import boto
#credentials stored in environment AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
cf = boto.connect_cloudfront()
oai = cf.create_origin_access_identity(comment='New identity for secure videos')
#We need the following two values for later steps:
print("Origin Access Identity ID: %s" % oai.id)
print("Origin Access Identity S3CanonicalUserId: %s" % oai.s3_user_id)
</code></pre>
<p><strong>3-修改对象上的ACL</p>
<p>现在我们有了特殊的S3用户帐户(上面创建的S3CanonicalUserId),我们需要让它访问我们的S3对象。我们可以通过打开对象(而不是bucket)的AWS控制台轻松地做到这一点“权限”选项卡,单击“添加更多权限”按钮,然后将上面得到的非常长的S3CanonicalUserId粘贴到新的“被授予者”字段中。确保您授予新的“打开/下载”权限。</p>
<p>您还可以使用以下boto脚本在代码中执行此操作:</p>
<pre><code>import boto
#credentials stored in environment AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
s3 = boto.connect_s3()
bucket_name = "stream.example.com"
bucket = s3.get_bucket(bucket_name)
object_name = "video.mp4"
key = bucket.get_key(object_name)
#Now add read permission to our new s3 account
s3_canonical_user_id = "<your S3CanonicalUserID from above>"
key.add_user_grant("READ", s3_canonical_user_id)
</code></pre>
<p><strong>4-创建cloudfront分发版</p>
<p>请注意,直到2.0版(在编写本文时尚未正式发布)之后,boto才完全支持自定义源代码和私有发行版。下面的代码从boto 2.0分支中提取一些代码,并将其组合在一起以使其正常运行,但它并不漂亮。2.0分支更优雅地处理这个问题-如果可能的话,一定要使用它!</p>
<pre><code>import boto
from boto.cloudfront.distribution import DistributionConfig
from boto.cloudfront.exception import CloudFrontServerError
import re
def get_domain_from_xml(xml):
results = re.findall("<DomainName>([^<]+)</DomainName>", xml)
return results[0]
#custom class to hack this until boto v2.0 is released
class HackedStreamingDistributionConfig(DistributionConfig):
def __init__(self, connection=None, origin='', enabled=False,
caller_reference='', cnames=None, comment='',
trusted_signers=None):
DistributionConfig.__init__(self, connection=connection,
origin=origin, enabled=enabled,
caller_reference=caller_reference,
cnames=cnames, comment=comment,
trusted_signers=trusted_signers)
#override the to_xml() function
def to_xml(self):
s = '<?xml version="1.0" encoding="UTF-8"?>\n'
s += '<StreamingDistributionConfig xmlns="http://cloudfront.amazonaws.com/doc/2010-07-15/">\n'
s += ' <S3Origin>\n'
s += ' <DNSName>%s</DNSName>\n' % self.origin
if self.origin_access_identity:
val = self.origin_access_identity
s += ' <OriginAccessIdentity>origin-access-identity/cloudfront/%s</OriginAccessIdentity>\n' % val
s += ' </S3Origin>\n'
s += ' <CallerReference>%s</CallerReference>\n' % self.caller_reference
for cname in self.cnames:
s += ' <CNAME>%s</CNAME>\n' % cname
if self.comment:
s += ' <Comment>%s</Comment>\n' % self.comment
s += ' <Enabled>'
if self.enabled:
s += 'true'
else:
s += 'false'
s += '</Enabled>\n'
if self.trusted_signers:
s += '<TrustedSigners>\n'
for signer in self.trusted_signers:
if signer == 'Self':
s += ' <Self/>\n'
else:
s += ' <AwsAccountNumber>%s</AwsAccountNumber>\n' % signer
s += '</TrustedSigners>\n'
if self.logging:
s += '<Logging>\n'
s += ' <Bucket>%s</Bucket>\n' % self.logging.bucket
s += ' <Prefix>%s</Prefix>\n' % self.logging.prefix
s += '</Logging>\n'
s += '</StreamingDistributionConfig>\n'
return s
def create(self):
response = self.connection.make_request('POST',
'/%s/%s' % ("2010-11-01", "streaming-distribution"),
{'Content-Type' : 'text/xml'},
data=self.to_xml())
body = response.read()
if response.status == 201:
return body
else:
raise CloudFrontServerError(response.status, response.reason, body)
cf = boto.connect_cloudfront()
s3_dns_name = "stream.example.com.s3.amazonaws.com"
comment = "example streaming distribution"
oai = "<OAI ID from step 2 above like E23KRHS6GDUF5L>"
#Create a distribution that does NOT need signed URLS
hsd = HackedStreamingDistributionConfig(connection=cf, origin=s3_dns_name, comment=comment, enabled=True)
hsd.origin_access_identity = oai
basic_dist = hsd.create()
print("Distribution with basic URLs: %s" % get_domain_from_xml(basic_dist))
#Create a distribution that DOES need signed URLS
hsd = HackedStreamingDistributionConfig(connection=cf, origin=s3_dns_name, comment=comment, enabled=True)
hsd.origin_access_identity = oai
#Add some required signers (Self means your own account)
hsd.trusted_signers = ['Self']
signed_dist = hsd.create()
print("Distribution with signed URLs: %s" % get_domain_from_xml(signed_dist))
</code></pre>
<p><strong>5-测试是否可以从cloudfront下载对象,但不能从s3下载对象</p>
<p>现在您应该能够验证:</p>
<ul>
<li>stream.example.com.s3.amazonaws.com/video.mp4-应给予AccessDenied</li>
<li>signed_distribution.cloudfront.net/video.mp4-应提供MissingKey(因为URL未签名)</li>
<li>basic_distribution.cloudfront.net/video.mp4-应该可以正常工作</li>
<ul>
<p>这些测试必须进行调整才能与流播放器一起使用,但基本思想是只有基本的cloudfront url才可以工作。</p>
<p><strong>6-为CloudFront创建密钥对</p>
<p>我认为唯一的办法就是通过亚马逊的网站。进入你的AWS“账户”页面,点击“安全凭证”链接。单击“密钥对”选项卡,然后单击“创建新密钥对”。这将为您生成新的密钥对并自动下载私钥文件(pk-xxxxxxxxx.pem)。保持密钥文件的安全性和私密性。还要记下亚马逊的“密钥对ID”,因为我们下一步需要它。</p>
<p><strong>7-用Python生成一些url</p>
<p>从boto版本2.0开始,似乎不支持生成签名的CloudFront url。Python没有在标准库中包含RSA加密例程,因此我们将不得不使用一个附加库。我在这个例子中使用了M2Crypto。</p>
<p>对于非流媒体分发,您必须使用完整的cloudfront URL作为资源,但是对于流媒体,我们仅使用视频文件的对象名称。有关生成仅持续5分钟的URL的完整示例,请参见下面的代码。</p>
<p>此代码松散地基于Amazon在CloudFront文档中提供的PHP示例代码。</p>
<pre><code>from M2Crypto import EVP
import base64
import time
def aws_url_base64_encode(msg):
msg_base64 = base64.b64encode(msg)
msg_base64 = msg_base64.replace('+', '-')
msg_base64 = msg_base64.replace('=', '_')
msg_base64 = msg_base64.replace('/', '~')
return msg_base64
def sign_string(message, priv_key_string):
key = EVP.load_key_string(priv_key_string)
key.reset_context(md='sha1')
key.sign_init()
key.sign_update(str(message))
signature = key.sign_final()
return signature
def create_url(url, encoded_signature, key_pair_id, expires):
signed_url = "%(url)s?Expires=%(expires)s&Signature=%(encoded_signature)s&Key-Pair-Id=%(key_pair_id)s" % {
'url':url,
'expires':expires,
'encoded_signature':encoded_signature,
'key_pair_id':key_pair_id,
}
return signed_url
def get_canned_policy_url(url, priv_key_string, key_pair_id, expires):
#we manually construct this policy string to ensure formatting matches signature
canned_policy = '{"Statement":[{"Resource":"%(url)s","Condition":{"DateLessThan":{"AWS:EpochTime":%(expires)s}}}]}' % {'url':url, 'expires':expires}
#now base64 encode it (must be URL safe)
encoded_policy = aws_url_base64_encode(canned_policy)
#sign the non-encoded policy
signature = sign_string(canned_policy, priv_key_string)
#now base64 encode the signature (URL safe as well)
encoded_signature = aws_url_base64_encode(signature)
#combine these into a full url
signed_url = create_url(url, encoded_signature, key_pair_id, expires);
return signed_url
def encode_query_param(resource):
enc = resource
enc = enc.replace('?', '%3F')
enc = enc.replace('=', '%3D')
enc = enc.replace('&', '%26')
return enc
#Set parameters for URL
key_pair_id = "APKAIAZCZRKVIO4BQ" #from the AWS accounts page
priv_key_file = "cloudfront-pk.pem" #your private keypair file
resource = 'video.mp4' #your resource (just object name for streaming videos)
expires = int(time.time()) + 300 #5 min
#Create the signed URL
priv_key_string = open(priv_key_file).read()
signed_url = get_canned_policy_url(resource, priv_key_string, key_pair_id, expires)
#Flash player doesn't like query params so encode them
enc_url = encode_query_param(signed_url)
print(enc_url)
</code></pre>
<p><strong>8-尝试URL</p>
<p>希望你现在应该有一个这样的工作网址:</p>
<pre><code>video.mp4%3FExpires%3D1309979985%26Signature%3DMUNF7pw1689FhMeSN6JzQmWNVxcaIE9mk1x~KOudJky7anTuX0oAgL~1GW-ON6Zh5NFLBoocX3fUhmC9FusAHtJUzWyJVZLzYT9iLyoyfWMsm2ylCDBqpy5IynFbi8CUajd~CjYdxZBWpxTsPO3yIFNJI~R2AFpWx8qp3fs38Yw_%26Key-Pair-Id%3DAPKAIAZRKVIO4BQ
</code></pre>
<p>把它放到js中,您应该会得到这样的东西(来自Amazon的CloudFront文档中的PHP示例):</p>
<pre><code>var so_canned = new SWFObject('http://location.domname.com/~jvngkhow/player.swf','mpl','640','360','9');
so_canned.addParam('allowfullscreen','true');
so_canned.addParam('allowscriptaccess','always');
so_canned.addParam('wmode','opaque');
so_canned.addVariable('file','video.mp4%3FExpires%3D1309979985%26Signature%3DMUNF7pw1689FhMeSN6JzQmWNVxcaIE9mk1x~KOudJky7anTuX0oAgL~1GW-ON6Zh5NFLBoocX3fUhmC9FusAHtJUzWyJVZLzYT9iLyoyfWMsm2ylCDBqpy5IynFbi8CUajd~CjYdxZBWpxTsPO3yIFNJI~R2AFpWx8qp3fs38Yw_%26Key-Pair-Id%3DAPKAIAZRKVIO4BQ');
so_canned.addVariable('streamer','rtmp://s3nzpoyjpct.cloudfront.net/cfx/st');
so_canned.write('canned');
</code></pre>
<hr/>
<p><strong>摘要</strong></p>
<p>如你所见,不太容易!boto v2将有助于设置发行版。我会找出是否有可能得到一些网址生成代码,以及改善这个伟大的图书馆!</p>