# ------------------------------------
# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.
# ------------------------------------
import logging
import os
from typing import TYPE_CHECKING
from .._internal import AsyncContextManager
from .._internal.decorators import log_get_token_async
from ... import CredentialUnavailableError
from ..._constants import EnvironmentVariables
if TYPE_CHECKING:
from typing import Any, Optional
from azure.core.credentials import AccessToken
from azure.core.credentials_async import AsyncTokenCredential
_LOGGER = logging.getLogger(__name__)
[docs]class ManagedIdentityCredential(AsyncContextManager):
"""Authenticates with an Azure managed identity in any hosting environment which supports managed identities.
This credential defaults to using a system-assigned identity. To configure a user-assigned identity, use one of
the keyword arguments. See `Azure Active Directory documentation
<https://docs.microsoft.com/azure/active-directory/managed-identities-azure-resources/overview>`_ for more
information about configuring managed identity for applications.
:keyword str client_id: a user-assigned identity's client ID or, when using Pod Identity, the client ID of an Azure
AD app registration. This argument is supported in all hosting environments.
:keyword identity_config: a mapping ``{parameter_name: value}`` specifying a user-assigned identity by its object
or resource ID, for example ``{"object_id": "..."}``. Check the documentation for your hosting environment to
learn what values it expects.
:paramtype identity_config: Mapping[str, str]
"""
def __init__(self, **kwargs: "Any") -> None:
self._credential = None # type: Optional[AsyncTokenCredential]
if os.environ.get(EnvironmentVariables.IDENTITY_ENDPOINT):
if os.environ.get(EnvironmentVariables.IDENTITY_HEADER):
if os.environ.get(EnvironmentVariables.IDENTITY_SERVER_THUMBPRINT):
_LOGGER.info("%s will use Service Fabric managed identity", self.__class__.__name__)
from .service_fabric import ServiceFabricCredential
self._credential = ServiceFabricCredential(**kwargs)
else:
_LOGGER.info("%s will use App Service managed identity", self.__class__.__name__)
from .app_service import AppServiceCredential
self._credential = AppServiceCredential(**kwargs)
elif os.environ.get(EnvironmentVariables.IMDS_ENDPOINT):
_LOGGER.info("%s will use Azure Arc managed identity", self.__class__.__name__)
from .azure_arc import AzureArcCredential
self._credential = AzureArcCredential(**kwargs)
else:
_LOGGER.info("%s will use Cloud Shell managed identity", self.__class__.__name__)
from .cloud_shell import CloudShellCredential
self._credential = CloudShellCredential(**kwargs)
elif os.environ.get(EnvironmentVariables.MSI_ENDPOINT):
if os.environ.get(EnvironmentVariables.MSI_SECRET):
_LOGGER.info("%s will use Azure ML managed identity", self.__class__.__name__)
from .azure_ml import AzureMLCredential
self._credential = AzureMLCredential(**kwargs)
else:
_LOGGER.info("%s will use Cloud Shell managed identity", self.__class__.__name__)
from .cloud_shell import CloudShellCredential
self._credential = CloudShellCredential(**kwargs)
elif all(os.environ.get(var) for var in EnvironmentVariables.TOKEN_EXCHANGE_VARS):
_LOGGER.info("%s will use token exchange", self.__class__.__name__)
from .token_exchange import TokenExchangeCredential
client_id = kwargs.pop("client_id", None) or os.environ.get(EnvironmentVariables.AZURE_CLIENT_ID)
if not client_id:
raise ValueError('Configure the environment with a client ID or pass a value for "client_id" argument')
self._credential = TokenExchangeCredential(
tenant_id=os.environ[EnvironmentVariables.AZURE_TENANT_ID],
client_id=client_id,
token_file_path=os.environ[EnvironmentVariables.AZURE_FEDERATED_TOKEN_FILE],
**kwargs
)
else:
from .imds import ImdsCredential
_LOGGER.info("%s will use IMDS", self.__class__.__name__)
self._credential = ImdsCredential(**kwargs)
async def __aenter__(self):
if self._credential:
await self._credential.__aenter__()
return self
[docs] async def close(self):
"""Close the credential's transport session."""
if self._credential:
await self._credential.__aexit__()
[docs] @log_get_token_async
async def get_token(self, *scopes: str, **kwargs: "Any") -> "AccessToken":
"""Asynchronously request an access token for `scopes`.
This method is called automatically by Azure SDK clients.
:param str scopes: desired scope for the access token. This credential allows only one scope per request.
:rtype: :class:`azure.core.credentials.AccessToken`
:raises ~azure.identity.CredentialUnavailableError: managed identity isn't available in the hosting environment
"""
if not self._credential:
raise CredentialUnavailableError(
message="No managed identity endpoint found. \n"
"The Target Azure platform could not be determined from environment variables. "
"Visit https://aka.ms/azsdk/python/identity/managedidentitycredential/troubleshoot to "
"troubleshoot this issue."
)
return await self._credential.get_token(*scopes, **kwargs)