Source code for google.appengine.api.capabilities

#!/usr/bin/env python
# Copyright 2007 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
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

"""Allows applications to identify API outages and scheduled downtime.

Some examples:
  def StoreUploadedProfileImage(self):
    uploaded_image = self.request.get('img')
    # If the images API is unavailable, we'll just skip the resize.
    if CapabilitySet('images').is_enabled():
      uploaded_image = images.resize(uploaded_image, 64, 64)

  def RenderHTMLForm(self):
    datastore_readonly = CapabilitySet('datastore_v3', capabilities=['write'])
    if datastore_readonly.is_enabled():
      # ...render form normally...
      # self.response.out('<p>Not accepting submissions right now: %s</p>' %
      # ...render form with form elements disabled...

  Individual API wrapper modules should expose CapabilitySet objects
  for users rather than relying on users to create them.  They may
  also create convenience methods (e.g. db.IsReadOnly()) that delegate
  to the relevant CapabilitySet.

Classes defined here:
  CapabilitySet: encapsulates one or more capabilities, allows introspection.
  UnknownCapabilityError: thrown when an unknown capability is requested.

import warnings

from google.appengine.api.capabilities import capability_service_pb
from google.appengine.base import capabilities_pb
from google.appengine.api import apiproxy_stub_map

IsEnabledRequest  = capability_service_pb.IsEnabledRequest
IsEnabledResponse = capability_service_pb.IsEnabledResponse
CapabilityConfig  = capabilities_pb.CapabilityConfig

[docs]class UnknownCapabilityError(Exception): """An unknown capability was requested."""
[docs]class CapabilitySet(object): """Encapsulates one or more capabilities. Capabilities can either be named explicitly, or inferred from the list of methods provided. If no capabilities or methods are provided, this will check whether the entire package is enabled. """ def __init__(self, package, capabilities=None, methods=None, stub_map=apiproxy_stub_map): """Constructor. Args: capabilities: list of strings methods: list of strings """ if capabilities is None: capabilities = [] if methods is None: methods = [] self._package = package self._capabilities = ['*'] + capabilities self._methods = methods self._stub_map = stub_map
[docs] def is_enabled(self): """Tests whether the capabilities is currently enabled. Returns: True if API calls that require these capabillities will succeed. Raises: UnknownCapabilityError, if a specified capability was not recognized. """ config = self._get_status() return config.summary_status() in (IsEnabledResponse.DEFAULT, IsEnabledResponse.ENABLED, IsEnabledResponse.SCHEDULED_FUTURE, IsEnabledResponse.SCHEDULED_NOW)
[docs] def will_remain_enabled_for(self, time=60): """Returns true if it will remain enabled for the specified amount of time. DEPRECATED: this method was never fully implemented and is considered deprecated. Use is_enabled() instead. Args: time: Number of seconds in the future to look when checking for scheduled downtime. Returns: True if there is no scheduled downtime for the specified capability within the amount of time specified. Raises: UnknownCapabilityError, if a specified capability was not recognized. """ warnings.warn('will_remain_enabled_for() is deprecated: ' 'use is_enabled instead.', DeprecationWarning, stacklevel=2) config = self._get_status() status = config.summary_status() if status in (IsEnabledResponse.DEFAULT, IsEnabledResponse.ENABLED): return True elif status == IsEnabledResponse.SCHEDULED_NOW: return False elif status == IsEnabledResponse.SCHEDULED_FUTURE: if config.has_time_until_scheduled(): return config.time_until_scheduled() >= time else: return True elif status == IsEnabledResponse.DISABLED: return False else: return False
[docs] def admin_message(self): """Get any administrator notice messages for these capabilities. Returns: A string containing one or more admin messages, or an empty string. Raises: UnknownCapabilityError, if a specified capability was not recognized. """ message_list = [] for config in self._get_status().config_list(): message = config.admin_message() if message and message not in message_list: message_list.append(message) return ' '.join(message_list)
def _get_status(self): """Get an IsEnabledResponse for the capabilities listed. Returns: IsEnabledResponse for the specified capabilities. Raises: UnknownCapabilityError: If an unknown capability was requested. """ req = IsEnabledRequest() req.set_package(self._package) for capability in self._capabilities: req.add_capability(capability) for method in self._methods: req.add_call(method) resp = capability_service_pb.IsEnabledResponse() self._stub_map.MakeSyncCall('capability_service', 'IsEnabled', req, resp) if resp.summary_status() == IsEnabledResponse.UNKNOWN: raise UnknownCapabilityError() return resp

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