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# Copyright 2016 Google LLC
#
# 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.
"""Google App Engine standard environment support.
This module provides authentication and signing for applications running on App
Engine in the standard environment using the `App Identity API`_.
.. _App Identity API:
https://cloud.google.com/appengine/docs/python/appidentity/
"""
import datetime
from google.auth import _helpers
from google.auth import credentials
from google.auth import crypt
# pytype: disable=import-error
try:
from google.appengine.api import app_identity
except ImportError:
app_identity = None
# pytype: enable=import-error
class Signer(crypt.Signer):
"""Signs messages using the App Engine App Identity service.
This can be used in place of :class:`google.auth.crypt.Signer` when
running in the App Engine standard environment.
"""
@property
def key_id(self):
"""Optional[str]: The key ID used to identify this private key.
.. warning::
This is always ``None``. The key ID used by App Engine can not
be reliably determined ahead of time.
"""
return None
@_helpers.copy_docstring(crypt.Signer)
def sign(self, message):
message = _helpers.to_bytes(message)
_, signature = app_identity.sign_blob(message)
return signature
def get_project_id():
"""Gets the project ID for the current App Engine application.
Returns:
str: The project ID
Raises:
EnvironmentError: If the App Engine APIs are unavailable.
"""
# pylint: disable=missing-raises-doc
# Pylint rightfully thinks EnvironmentError is OSError, but doesn't
# realize it's a valid alias.
if app_identity is None:
raise EnvironmentError("The App Engine APIs are not available.")
return app_identity.get_application_id()
class Credentials(
credentials.Scoped, credentials.Signing, credentials.CredentialsWithQuotaProject
):
"""App Engine standard environment credentials.
These credentials use the App Engine App Identity API to obtain access
tokens.
"""
def __init__(
self,
scopes=None,
default_scopes=None,
service_account_id=None,
quota_project_id=None,
):
"""
Args:
scopes (Sequence[str]): Scopes to request from the App Identity
API.
default_scopes (Sequence[str]): Default scopes passed by a
Google client library. Use 'scopes' for user-defined scopes.
service_account_id (str): The service account ID passed into
:func:`google.appengine.api.app_identity.get_access_token`.
If not specified, the default application service account
ID will be used.
quota_project_id (Optional[str]): The project ID used for quota
and billing.
Raises:
EnvironmentError: If the App Engine APIs are unavailable.
"""
# pylint: disable=missing-raises-doc
# Pylint rightfully thinks EnvironmentError is OSError, but doesn't
# realize it's a valid alias.
if app_identity is None:
raise EnvironmentError("The App Engine APIs are not available.")
super(Credentials, self).__init__()
self._scopes = scopes
self._default_scopes = default_scopes
self._service_account_id = service_account_id
self._signer = Signer()
self._quota_project_id = quota_project_id
@_helpers.copy_docstring(credentials.Credentials)
def refresh(self, request):
scopes = self._scopes if self._scopes is not None else self._default_scopes
# pylint: disable=unused-argument
token, ttl = app_identity.get_access_token(scopes, self._service_account_id)
expiry = datetime.datetime.utcfromtimestamp(ttl)
self.token, self.expiry = token, expiry
@property
def service_account_email(self):
"""The service account email."""
if self._service_account_id is None:
self._service_account_id = app_identity.get_service_account_name()
return self._service_account_id
@property
def requires_scopes(self):
"""Checks if the credentials requires scopes.
Returns:
bool: True if there are no scopes set otherwise False.
"""
return not self._scopes and not self._default_scopes
@_helpers.copy_docstring(credentials.Scoped)
def with_scopes(self, scopes, default_scopes=None):
return self.__class__(
scopes=scopes,
default_scopes=default_scopes,
service_account_id=self._service_account_id,
quota_project_id=self.quota_project_id,
)
@_helpers.copy_docstring(credentials.CredentialsWithQuotaProject)
def with_quota_project(self, quota_project_id):
return self.__class__(
scopes=self._scopes,
service_account_id=self._service_account_id,
quota_project_id=quota_project_id,
)
@_helpers.copy_docstring(credentials.Signing)
def sign_bytes(self, message):
return self._signer.sign(message)
@property
@_helpers.copy_docstring(credentials.Signing)
def signer_email(self):
return self.service_account_email
@property
@_helpers.copy_docstring(credentials.Signing)
def signer(self):
return self._signer
|
