Open Source Monorail

appengine/monorail/framework/gcs_helpers.py

+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is govered by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""Set of helpers for interacting with Google Cloud Storage."""
+
+import base64
+import logging
+import os
+import time
+import urllib
+import uuid
+
+from datetime import datetime, timedelta
+
+from google.appengine.api import app_identity
+from google.appengine.api import images
+from third_party import cloudstorage
+
+from framework import filecontent
+
+
+ATTACHMENT_TTL = timedelta(seconds=30)
+
+IS_DEV_APPSERVER = (
+    'development' in os.environ.get('SERVER_SOFTWARE', '').lower())
+
+RESIZABLE_MIME_TYPES = ['image/png', 'image/jpg', 'image/jpeg', 'image/gif']
+
+DEFAULT_THUMB_WIDTH = 250
+DEFAULT_THUMB_HEIGHT = 200
+LOGO_THUMB_WIDTH = 110
+LOGO_THUMB_HEIGHT = 30
+
+
+def _Now():
+  return datetime.utcnow()
+
+
+class UnsupportedMimeType(Exception):
+  pass
+
+
+def DeleteObjectFromGCS(object_id):
+  object_path = ('/' + app_identity.get_default_gcs_bucket_name() + object_id)
+  cloudstorage.delete(object_path)
+
+
+def StoreObjectInGCS(
+    content, mime_type, project_id, thumb_width=DEFAULT_THUMB_WIDTH,
+    thumb_height=DEFAULT_THUMB_HEIGHT):
+  bucket_name = app_identity.get_default_gcs_bucket_name()
+  guid = uuid.uuid4()
+  object_id = '/%s/attachments/%s' % (project_id, guid)
+  object_path = '/' + bucket_name + object_id
+  with cloudstorage.open(object_path, 'w', mime_type) as f:
+    f.write(content)
+
+  if mime_type in RESIZABLE_MIME_TYPES:
+    # Create and save a thumbnail too.
+    thumb_content = None
+    try:
+      thumb_content = images.resize(content, thumb_width, thumb_height)
+    except Exception, e:
+      # Do not raise exception for incorrectly formed images.
+      # See https://bugs.chromium.org/p/monorail/issues/detail?id=597 for more
+      # detail.
+      logging.exception(e)
+    if thumb_content:
+      thumb_path = '%s-thumbnail' % object_path
+      with cloudstorage.open(thumb_path, 'w', 'image/png') as f:
+        f.write(thumb_content)
+
+  return object_id
+
+
+def CheckMimeTypeResizable(mime_type):
+  if mime_type not in RESIZABLE_MIME_TYPES:
+    raise UnsupportedMimeType(
+        'Please upload a logo with one of the following mime types:\n%s' %
+            ', '.join(RESIZABLE_MIME_TYPES))
+
+
+def StoreLogoInGCS(file_name, content, project_id):
+  mime_type = filecontent.GuessContentTypeFromFilename(file_name)
+  CheckMimeTypeResizable(mime_type)
+  if '\\' in file_name:  # IE insists on giving us the whole path.
+    file_name = file_name[file_name.rindex('\\') + 1:]
+  return StoreObjectInGCS(
+      content, mime_type, project_id, thumb_width=LOGO_THUMB_WIDTH,
+      thumb_height=LOGO_THUMB_HEIGHT)
+
+
+def SignUrl(gcs_filename):
+  expiration_dt = _Now() + ATTACHMENT_TTL
+  expiration = int(time.mktime(expiration_dt.timetuple()))
+  signature_string = '\n'.join([
+      'GET',
+      '',  # Optional MD5, which we don't have.
+      '',  # Optional content-type, which only applies to uploads.
+      str(expiration),
+      gcs_filename]).encode('utf-8')
+
+  signature_bytes = app_identity.sign_blob(signature_string)[1]
+
+  query_params = {'GoogleAccessId': app_identity.get_service_account_name(),
+                  'Expires': str(expiration),
+                  'Signature': base64.b64encode(signature_bytes)}
+
+  result = 'https://storage.googleapis.com{resource}?{querystring}'
+
+  if IS_DEV_APPSERVER:
+    result = '/_ah/gcs{resource}?{querystring}'
+
+  return result.format(
+        resource=gcs_filename, querystring=urllib.urlencode(query_params))
+