CDN samples dir with snippet for signing urls

cdn/README.rst.in

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+# Used to generate README.rst
+
+product:
+  name: Google Cloud CDN
+  short_name: Cloud CDN
+  url: https://cloud.google.com/cdn/docs
+  description: >
+    'Google Cloud CDN'_ enables low-latency, low-cost content delivery using
+    Google's global network
+
+samples:
+  - name: Snippets
+    file: snippets.py
+    show_help: true
+
+folder: cdn

cdn/snippets.py

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+#!/usr/bin/env python
+#
+# Copyright 2017 Google, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""This application demonstrates how to perform operations on data (content)
+when using Google Cloud CDN (Content Delivery Network).
+
+For more information, see the README.md under /cdn and the documentation
+at https://cloud.google.com/cdn/docs.
+"""
+
+import argparse
+import base64
+import datetime
+import hashlib
+import hmac
+import urlparse
+
+# [BEGIN sign_url]
+def sign_url(url, key_name, decoded_base64_key, expiration_datetime):
+    """Gets the Signed URL string for the specified URL and configuration.
+
+    Args:
+        url: The URL to sign.
+        key_name: key name for the authorization secret key.
+        decoded_base64_key: base64 decoded secret key value to sign the url.
+        expiration_datetime: expiration time as a UTC datetime object.
+
+    Returns:
+        Returns the Signed URL appended with the query parameters based on the
+        specified configuration.  Roughly of the form:
+        {url}{separator}Expires={expiration}&KeyName={key_name}&Signature={signature}
+
+    """
+    stripped_url = url.strip()
+    parsed_url = urlparse.urlsplit(stripped_url)
+    query_params = urlparse.parse_qs(parsed_url.query, keep_blank_values=True)
+    epoch = datetime.datetime.utcfromtimestamp(0)
+    expiration_timestamp = int((expiration_datetime - epoch).total_seconds())
+
+    url_to_sign = '{url}{separator}Expires={expires}&KeyName={key_name}'.format(
+            url=stripped_url,
+            separator='&' if query_params else '?',
+            expires=expiration_timestamp,
+            key_name=key_name)
+
+    signature = base64.urlsafe_b64encode(
+            hmac.new(decoded_base64_key, url_to_sign, hashlib.sha1).digest())
+
+    return '{url}&Signature={signature}'.format(
+            url=url_to_sign, signature=signature)
+# [END sign_url]
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(
+            description=__doc__,
+            formatter_class=argparse.RawDescriptionHelpFormatter)
+
+    subparsers = parser.add_subparsers(dest='command')
+
+    sign_url_parser = subparsers.add_parser(
+            'sign-url',
+            help="Sign a URL to grant temporary authorized access.")
+    sign_url_parser.add_argument(
+            'url', help='The URL to sign')
+    sign_url_parser.add_argument(
+            'key_name',
+            help='Key name for the authorization secret key.')
+    sign_url_parser.add_argument(
+            'encoded_base64_key',
+            help='The base64 encoded secret key value to use for signing.')
+    sign_url_parser.add_argument(
+            'expiration_timestamp',
+            help='Expiration time expessed as seconds since the epoch.')
+
+    args = parser.parse_args()
+
+    if args.command == 'sign-url':
+        expiration_datetime = datetime.datetime.utcfromtimestamp(
+                float(args.expiration_timestamp))
+        decoded_key = base64.urlsafe_b64decode(args.encoded_base64_key)
+        print(sign_url(args.url, args.key_name, decoded_key, expiration_datetime))
+