157 lines
4.9 KiB
Python
157 lines
4.9 KiB
Python
# Copyright 2016 Google Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Google App Engine standard environment support.
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This module provides authentication and signing for applications running on App
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Engine in the standard environment using the `App Identity API`_.
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.. _App Identity API:
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https://cloud.google.com/appengine/docs/python/appidentity/
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"""
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import datetime
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from google.auth import _helpers
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from google.auth import credentials
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from google.auth import crypt
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# pytype: disable=import-error
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try:
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from google.appengine.api import app_identity
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except ImportError:
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app_identity = None
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# pytype: enable=import-error
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class Signer(crypt.Signer):
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"""Signs messages using the App Engine App Identity service.
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This can be used in place of :class:`google.auth.crypt.Signer` when
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running in the App Engine standard environment.
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"""
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@property
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def key_id(self):
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"""Optional[str]: The key ID used to identify this private key.
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.. warning::
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This is always ``None``. The key ID used by App Engine can not
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be reliably determined ahead of time.
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"""
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return None
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@_helpers.copy_docstring(crypt.Signer)
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def sign(self, message):
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message = _helpers.to_bytes(message)
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_, signature = app_identity.sign_blob(message)
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return signature
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def get_project_id():
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"""Gets the project ID for the current App Engine application.
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Returns:
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str: The project ID
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Raises:
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EnvironmentError: If the App Engine APIs are unavailable.
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"""
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# pylint: disable=missing-raises-doc
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# Pylint rightfully thinks EnvironmentError is OSError, but doesn't
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# realize it's a valid alias.
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if app_identity is None:
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raise EnvironmentError(
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'The App Engine APIs are not available.')
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return app_identity.get_application_id()
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class Credentials(credentials.Scoped, credentials.Signing,
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credentials.Credentials):
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"""App Engine standard environment credentials.
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These credentials use the App Engine App Identity API to obtain access
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tokens.
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"""
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def __init__(self, scopes=None, service_account_id=None):
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"""
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Args:
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scopes (Sequence[str]): Scopes to request from the App Identity
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API.
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service_account_id (str): The service account ID passed into
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:func:`google.appengine.api.app_identity.get_access_token`.
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If not specified, the default application service account
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ID will be used.
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Raises:
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EnvironmentError: If the App Engine APIs are unavailable.
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"""
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# pylint: disable=missing-raises-doc
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# Pylint rightfully thinks EnvironmentError is OSError, but doesn't
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# realize it's a valid alias.
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if app_identity is None:
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raise EnvironmentError(
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'The App Engine APIs are not available.')
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super(Credentials, self).__init__()
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self._scopes = scopes
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self._service_account_id = service_account_id
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self._signer = Signer()
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@_helpers.copy_docstring(credentials.Credentials)
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def refresh(self, request):
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# pylint: disable=unused-argument
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token, ttl = app_identity.get_access_token(
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self._scopes, self._service_account_id)
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expiry = datetime.datetime.utcfromtimestamp(ttl)
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self.token, self.expiry = token, expiry
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@property
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def service_account_email(self):
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"""The service account email."""
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if self._service_account_id is None:
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self._service_account_id = app_identity.get_service_account_name()
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return self._service_account_id
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@property
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def requires_scopes(self):
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"""Checks if the credentials requires scopes.
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Returns:
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bool: True if there are no scopes set otherwise False.
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"""
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return not self._scopes
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@_helpers.copy_docstring(credentials.Scoped)
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def with_scopes(self, scopes):
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return self.__class__(
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scopes=scopes, service_account_id=self._service_account_id)
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@_helpers.copy_docstring(credentials.Signing)
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def sign_bytes(self, message):
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return self._signer.sign(message)
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@property
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@_helpers.copy_docstring(credentials.Signing)
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def signer_email(self):
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return self.service_account_email
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@property
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@_helpers.copy_docstring(credentials.Signing)
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def signer(self):
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return self._signer
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