1# Copyright 2014 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5import os
6import environment
7
8from caching_file_system import CachingFileSystem
9from empty_dir_file_system import EmptyDirFileSystem
10from extensions_paths import LOCAL_GCS_DIR, LOCAL_GCS_DEBUG_CONF
11from local_file_system import LocalFileSystem
12from path_util import IsDirectory, ToDirectory
13
14class CloudStorageFileSystemProvider(object):
15  '''Provides CloudStorageFileSystem bound to a GCS bucket.
16  '''
17  def __init__(self, object_store_creator):
18    self._object_store_creator = object_store_creator
19
20  def Create(self, bucket):
21    '''Creates a CloudStorageFileSystemProvider.
22
23    |bucket| is the name of GCS bucket, eg devtools-docs. It is expected
24             that this bucket has Read permission for this app in its ACLs.
25
26    Optional configuration can be set in a local_debug/gcs_debug.conf file:
27      use_local_fs=True|False
28      access_token=<token>
29      remote_bucket_prefix=<prefix>
30
31    If running in Preview mode or in Development mode with use_local_fs set to
32    True, buckets and files are looked inside the local_debug folder instead
33    of in the real GCS server. Preview server does not support direct GCS
34    access, so it is always forced to use a LocalFileSystem.
35
36    For real GCS access in the Development mode (dev_appserver.py),
37    access_token and remote_bucket_prefix options can be
38    used to change the way GCS files are accessed. Both are ignored in a real
39    appengine instance.
40
41    "access_token" is always REQUIRED on dev_appengine, otherwise you will
42    get 404 (auth) errors. You can get one access_token valid for a few minutes
43    by typing:
44      gsutil -d ls 2>&1 | grep "Bearer" |
45         sed "s/.*Bearer \(.*\).r.nUser-Agent.*/access_token=\1/" )"
46
47    A sample output would be:
48      access_token=ya29.1.AADtN_VW5ibbfLHV5cMIK5ss4bHtVzBXpa4byjd
49
50    Now add this line to the local_debug/gcs_debug.conf file and restart the
51    appengine development server.
52
53    Remember that you will need a new access_token every ten minutes or
54    so. If you get 404 errors on log, update it. Access token is not
55    used for a deployed appengine app, only if you use dev_appengine.py.
56
57    remote_bucket_prefix is useful if you want to test on your own GCS buckets
58    before using the real GCS buckets.
59
60    '''
61    if not environment.IsReleaseServer() and not environment.IsDevServer():
62      bucket_local_path = os.path.join(LOCAL_GCS_DIR, bucket)
63      if IsDirectory(bucket_local_path):
64        return LocalFileSystem(bucket_local_path)
65      else:
66        return EmptyDirFileSystem()
67
68    debug_access_token = None
69    debug_bucket_prefix = None
70    use_local_fs = False
71
72    if environment.IsDevServer() and os.path.exists(LOCAL_GCS_DEBUG_CONF):
73      with open(LOCAL_GCS_DEBUG_CONF, "r") as token_file:
74        properties = dict(line.strip().split('=', 1) for line in token_file)
75      use_local_fs = properties.get('use_local_fs', 'False')=='True'
76      debug_access_token = properties.get('access_token', None)
77      debug_bucket_prefix = properties.get('remote_bucket_prefix', None)
78
79    if environment.IsDevServer() and use_local_fs:
80      return LocalFileSystem(ToDirectory(os.path.join(LOCAL_GCS_DIR, bucket)))
81
82    # gcs_file_system has strong dependencies on runtime appengine APIs,
83    # so we only import it when we are sure we are not on preview.py or tests.
84    from gcs_file_system import CloudStorageFileSystem
85    return CachingFileSystem(CloudStorageFileSystem(bucket,
86        debug_access_token, debug_bucket_prefix),
87        self._object_store_creator)
88
89  @staticmethod
90  def ForEmpty():
91    class EmptyImpl(object):
92      def Create(self, bucket):
93        return EmptyDirFileSystem()
94    return EmptyImpl()
95