add GCS support to docs server

chrome/common/extensions/docs/server2/gcs_file_system_provider.py

+# Copyright 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import environment
+
+from empty_dir_file_system import EmptyDirFileSystem
+from extensions_paths import LOCAL_GCS_DIR, LOCAL_GCS_DEBUG_CONF
+from local_file_system import LocalFileSystem
+
+class CloudStorageFileSystemProvider(object):
+  '''Provides CloudStorageFileSystem bound to a GCS bucket.
+  '''
+  def __init__(self, object_store_creator):
+    self._object_store_creator = object_store_creator
+
+  def Create(self, bucket):
+    '''Creates a CloudStorageFileSystemProvider.
+
+    |bucket| is the name of GCS bucket, eg devtools-docs. It is expected
+             that this bucket has Read permission for this app in its ACLs.
+
+    Optional configuration can be set in a local_debug/gcs_debug.conf file:
+      use_local_fs=True|False
+      access_token=<token>
+      remote_bucket_prefix=<prefix>
+
+    If running in Preview mode or in Development mode with use_local_fs set to
+    True, buckets and files are looked inside the local_debug folder instead
+    of in the real GCS server. Preview server does not support direct GCS
+    access, so it is always forced to use a LocalFileSystem.
+
+    For real GCS access in the Development mode (dev_appserver.py),
+    access_token and remote_bucket_prefix options can be
+    used to change the way GCS files are accessed. Both are ignored in a real
+    appengine instance.
+
+    "access_token" is always REQUIRED on dev_appengine, otherwise you will
+    get 404 (auth) errors. You can get one access_token valid for a few minutes
+    by typing:
+      gsutil -d ls 2>&1 | grep "Bearer" |
+         sed "s/.*Bearer \(.*\).r.nUser-Agent.*/access_token=\1/" )"
+
+    A sample output would be:
+      access_token=ya29.1.AADtN_VW5ibbfLHV5cMIK5ss4bHtVzBXpa4byjd
+
+    Now add this line to the local_debug/gcs_debug.conf file and restart the
+    appengine development server.
+
+    Remember that you will need a new access_token every ten minutes or
+    so. If you get 404 errors on log, update it. Access token is not
+    used for a deployed appengine app, only if you use dev_appengine.py.
+
+    remote_bucket_prefix is useful if you want to test on your own GCS buckets
+    before using the real GCS buckets.
+
+    '''
+    if not environment.IsReleaseServer() and not environment.IsDevServer():
+      return LocalFileSystem(os.path.join(LOCAL_GCS_DIR, bucket))
+
+    debug_access_token = None
+    debug_bucket_prefix = None
+    use_local_fs = False
+
+    if environment.IsDevServer() and os.path.exists(LOCAL_GCS_DEBUG_CONF):
+      with open(LOCAL_GCS_DEBUG_CONF, "r") as token_file:
+        properties = dict(line.strip().split('=', 1) for line in token_file)
+      use_local_fs = properties.get('use_local_fs', 'False')=='True'
+      debug_access_token = properties.get('access_token', None)
+      debug_bucket_prefix = properties.get('remote_bucket_prefix', None)
+
+    if environment.IsDevServer() and use_local_fs:
+      return LocalFileSystem(os.path.join(LOCAL_GCS_DIR, bucket))
+
+    # gcs_file_system has strong dependencies on runtime appengine APIs,
+    # so we only import it when we are sure we are not on preview.py or tests.
+    from gcs_file_system import CloudStorageFileSystem
+    return CloudStorageFileSystem(
+        bucket, debug_access_token, debug_bucket_prefix)
+
+
+  @staticmethod
+  def ForEmpty():
+    class EmptyImpl(object):
+      def Create(self, bucket):
+        return EmptyDirFileSystem()
+    return EmptyImpl()