[storage] feat: add post policy sample (#3231)

* feat: add post policy sample

* use 1.27.0

* fix

* simplify iterator

Co-authored-by: Jonathan Lui <jonathanlui@google.com>

storage/cloud-client/requirements.txt

@@ -1,2 +1,2 @@
 google-cloud-pubsub==1.1.0
-google-cloud-storage==1.26.0
+google-cloud-storage==1.27.0

storage/cloud-client/snippets_test.py

@@ -40,6 +40,7 @@
 import storage_generate_signed_url_v2
 import storage_generate_signed_url_v4
 import storage_generate_upload_signed_url_v4
+import storage_generate_signed_post_policy_v4
 import storage_set_bucket_default_kms_key
 
 KMS_KEY = os.environ["CLOUD_KMS_KEY"]
@@ -202,6 +203,22 @@ def test_generate_upload_signed_url_v4(test_bucket, capsys):
     assert blob.download_as_string() == content
 
 
+def test_generate_signed_policy_v4(test_bucket, capsys):
+    blob_name = "storage_snippets_test_form"
+    short_name = storage_generate_signed_post_policy_v4
+    form = short_name.generate_signed_post_policy_v4(
+        test_bucket.name, blob_name
+    )
+    assert "name='key' value='{}'".format(blob_name) in form
+    assert "name='x-goog-signature'" in form
+    assert "name='x-goog-date'" in form
+    assert "name='x-goog-credential'" in form
+    assert "name='x-goog-algorithm' value='GOOG4-RSA-SHA256'" in form
+    assert "name='policy'" in form
+    assert "name='x-goog-meta-test' value='data'" in form
+    assert "type='file' name='file'/>" in form
+
+
 def test_rename_blob(test_blob):
     bucket = storage.Client().bucket(test_blob.bucket.name)
 

storage/cloud-client/storage_generate_signed_post_policy_v4.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python
+
+# Copyright 2020 Google Inc. All Rights Reserved.
+#
+# 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.
+
+import sys
+
+# [START storage_generate_signed_post_policy_v4]
+from google.cloud import storage
+import datetime
+
+
+def generate_signed_post_policy_v4(bucket_name, blob_name):
+    """Generates a v4 POST Policy and prints an HTML form."""
+    # bucket_name = 'your-bucket-name'
+    # blob_name = 'your-object-name'
+
+    storage_client = storage.Client()
+
+    policy = storage_client.generate_signed_post_policy_v4(
+        bucket_name,
+        blob_name,
+        expiration=datetime.timedelta(minutes=10),
+        fields={
+          'x-goog-meta-test': 'data'
+        }
+    )
+
+    # Create an HTML form with the provided policy
+    header = "<form action='{}' method='POST' enctype='multipart/form-data'>\n"
+    form = header.format(policy["url"])
+
+    # Include all fields returned in the HTML form as they're required
+    for key, value in policy["fields"].items():
+        form += "  <input name='{}' value='{}' type='hidden'/>\n".format(key, value)
+
+    form += "  <input type='file' name='file'/><br />\n"
+    form += "  <input type='submit' value='Upload File' name='submit'/><br />\n"
+    form += "</form>"
+
+    print(form)
+
+    return form
+
+
+# [END storage_generate_signed_post_policy_v4]
+
+if __name__ == "__main__":
+    generate_signed_post_policy_v4(
+        bucket_name=sys.argv[1], blob_name=sys.argv[2]
+    )