사진 공유 SNS 서버 개발하기 part 2

@_bucket_check
def generate_presigned_url_(self, Key=None, ExpiresIn=0):
    """ client를 이용해서 signed url을 생성 """
    Params = dict(Bucket=self.bucket_name, Key=Key)
    return self.client.generate_presigned_url(
        ClientMethod='get_object', Params=Params, ExpiresIn=ExpiresIn, HttpMethod='GET'
    )

def generate_presigned_url(self, url, expire_sec):
    expire_date = datetime.utcnow() + timedelta(seconds=expire_sec)
    return self.CloudFrontSigner.generate_presigned_url(url, date_less_than=expire_date)

class CloudFront:
    # https://docs.aws.amazon.com/ko_kr/AmazonCloudFront/latest/DeveloperGuide/private-content-trusted-signers.html#private-content-creating-cloudfront-key-pairs
    # open ssl 500 error가 나서 사용 불가능으로 판단해서 서버에서 직접 생성으로 변경
    def __init__(self):
        self.key_id = 'key_id'  # TODO 나중에는 .json 형식으로 따로 관리하자.
        self.key_file = os.path.dirname(os.path.abspath(__file__)) + '/pk-key_file.pem'
        self.CloudFrontSigner = CloudFrontSigner(self.key_id, self.rsa_signer)

    @staticmethod
    def rsa_signer(message):
        with open(key_file, 'rb') as f:
            private_key = serialization.load_pem_private_key(
                f.read(),
                password=None,
                backend=default_backend()
            )
        signer = private_key.signer(padding.PKCS1v15(), hashes.SHA1())
        signer.update(message)
        return signer.finalize()

    def generate_presigned_url_(self, url, expire_sec, client_id):
        expire_sec += int(time.time())
        recipe = {
            'Statement': [{
                'Resource': url,
                'Condition': {'DateLessThan': {'AWS:EpochTime': expire_sec}}
            }]
        }
        recipe = ((json.dumps(recipe).rstrip('\r\n')).replace(' ', '')).rstrip(os.linesep)
        path = '/var/tmp/bridgefan/' + client_id
        with open(path, 'w') as f:
            f.write(recipe)
        signature = cmd(
            'cat {0} | openssl sha1 -sign {1} | openssl base64 | tr "+=/" "-_~"'.format(path, self.key_file)
        )
        os.remove(path)
        url = '{0}?Expires={1}&Signature={2}&Key-Pair-Id={3}'.format(url, expire_sec, signature, self.key_id)
        return ((url.rstrip('\r\n')).replace(' ', '')).replace('\n', '')