# Copyright 2020 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. """Identity Pool Credentials. This module provides credentials to access Google Cloud resources from on-prem or non-Google Cloud platforms which support external credentials (e.g. OIDC ID tokens) retrieved from local file locations or local servers. This includes Microsoft Azure and OIDC identity providers (e.g. K8s workloads registered with Hub with Hub workload identity enabled). These credentials are recommended over the use of service account credentials in on-prem/non-Google Cloud platforms as they do not involve the management of long-live service account private keys. Identity Pool Credentials are initialized using external_account arguments which are typically loaded from an external credentials file or an external credentials URL. Unlike other Credentials that can be initialized with a list of explicit arguments, secrets or credentials, external account clients use the environment and hints/guidelines provided by the external_account JSON file to retrieve credentials and exchange them for Google access tokens. """ try: from collections.abc import Mapping # Python 2.7 compatibility except ImportError: # pragma: NO COVER from collections import Mapping import io import json import os from google.auth import _helpers from google.auth import exceptions from google.auth import external_account class Credentials(external_account.Credentials): """External account credentials sourced from files and URLs.""" def __init__( self, audience, subject_token_type, token_url, credential_source, *args, **kwargs ): """Instantiates an external account credentials object from a file/URL. Args: audience (str): The STS audience field. subject_token_type (str): The subject token type. token_url (str): The STS endpoint URL. credential_source (Mapping): The credential source dictionary used to provide instructions on how to retrieve external credential to be exchanged for Google access tokens. Example credential_source for url-sourced credential:: { "url": "http://www.example.com", "format": { "type": "json", "subject_token_field_name": "access_token", }, "headers": {"foo": "bar"}, } Example credential_source for file-sourced credential:: { "file": "/path/to/token/file.txt" } args (List): Optional positional arguments passed into the underlying :meth:`~external_account.Credentials.__init__` method. kwargs (Mapping): Optional keyword arguments passed into the underlying :meth:`~external_account.Credentials.__init__` method. Raises: google.auth.exceptions.RefreshError: If an error is encountered during access token retrieval logic. ValueError: For invalid parameters. .. note:: Typically one of the helper constructors :meth:`from_file` or :meth:`from_info` are used instead of calling the constructor directly. """ super(Credentials, self).__init__( audience=audience, subject_token_type=subject_token_type, token_url=token_url, credential_source=credential_source, *args, **kwargs ) if not isinstance(credential_source, Mapping): self._credential_source_file = None self._credential_source_url = None else: self._credential_source_file = credential_source.get("file") self._credential_source_url = credential_source.get("url") self._credential_source_headers = credential_source.get("headers") credential_source_format = credential_source.get("format", {}) # Get credential_source format type. When not provided, this # defaults to text. self._credential_source_format_type = ( credential_source_format.get("type") or "text" ) # environment_id is only supported in AWS or dedicated future external # account credentials. if "environment_id" in credential_source: raise exceptions.MalformedError( "Invalid Identity Pool credential_source field 'environment_id'" ) if self._credential_source_format_type not in ["text", "json"]: raise exceptions.MalformedError( "Invalid credential_source format '{}'".format( self._credential_source_format_type ) ) # For JSON types, get the required subject_token field name. if self._credential_source_format_type == "json": self._credential_source_field_name = credential_source_format.get( "subject_token_field_name" ) if self._credential_source_field_name is None: raise exceptions.MalformedError( "Missing subject_token_field_name for JSON credential_source format" ) else: self._credential_source_field_name = None if self._credential_source_file and self._credential_source_url: raise exceptions.MalformedError( "Ambiguous credential_source. 'file' is mutually exclusive with 'url'." ) if not self._credential_source_file and not self._credential_source_url: raise exceptions.MalformedError( "Missing credential_source. A 'file' or 'url' must be provided." ) @_helpers.copy_docstring(external_account.Credentials) def retrieve_subject_token(self, request): return self._parse_token_data( self._get_token_data(request), self._credential_source_format_type, self._credential_source_field_name, ) def _get_token_data(self, request): if self._credential_source_file: return self._get_file_data(self._credential_source_file) else: return self._get_url_data( request, self._credential_source_url, self._credential_source_headers ) def _get_file_data(self, filename): if not os.path.exists(filename): raise exceptions.RefreshError("File '{}' was not found.".format(filename)) with io.open(filename, "r", encoding="utf-8") as file_obj: return file_obj.read(), filename def _get_url_data(self, request, url, headers): response = request(url=url, method="GET", headers=headers) # support both string and bytes type response.data response_body = ( response.data.decode("utf-8") if hasattr(response.data, "decode") else response.data ) if response.status != 200: raise exceptions.RefreshError( "Unable to retrieve Identity Pool subject token", response_body ) return response_body, url def _parse_token_data( self, token_content, format_type="text", subject_token_field_name=None ): content, filename = token_content if format_type == "text": token = content else: try: # Parse file content as JSON. response_data = json.loads(content) # Get the subject_token. token = response_data[subject_token_field_name] except (KeyError, ValueError): raise exceptions.RefreshError( "Unable to parse subject_token from JSON file '{}' using key '{}'".format( filename, subject_token_field_name ) ) if not token: raise exceptions.RefreshError( "Missing subject_token in the credential_source file" ) return token @classmethod def from_info(cls, info, **kwargs): """Creates an Identity Pool Credentials instance from parsed external account info. Args: info (Mapping[str, str]): The Identity Pool external account info in Google format. kwargs: Additional arguments to pass to the constructor. Returns: google.auth.identity_pool.Credentials: The constructed credentials. Raises: ValueError: For invalid parameters. """ return super(Credentials, cls).from_info(info, **kwargs) @classmethod def from_file(cls, filename, **kwargs): """Creates an IdentityPool Credentials instance from an external account json file. Args: filename (str): The path to the IdentityPool external account json file. kwargs: Additional arguments to pass to the constructor. Returns: google.auth.identity_pool.Credentials: The constructed credentials. """ return super(Credentials, cls).from_file(filename, **kwargs)