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# ------------------------------------
# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.
# ------------------------------------
import logging
import os
from typing import Optional, Union, Any
from azure.core.credentials import AccessToken
from .._internal.decorators import log_get_token_async
from ... import CredentialUnavailableError
from ..._constants import EnvironmentVariables
from .._internal import AsyncContextManager
from .certificate import CertificateCredential
from .client_secret import ClientSecretCredential
_LOGGER = logging.getLogger(__name__)
class EnvironmentCredential(AsyncContextManager):
"""A credential configured by environment variables.
This credential is capable of authenticating as a service principal using a client secret or a certificate, or as
a user with a username and password. Configuration is attempted in this order, using these environment variables:
Service principal with secret:
- **AZURE_TENANT_ID**: ID of the service principal's tenant. Also called its 'directory' ID.
- **AZURE_CLIENT_ID**: the service principal's client ID
- **AZURE_CLIENT_SECRET**: one of the service principal's client secrets
- **AZURE_AUTHORITY_HOST**: authority of a Microsoft Entra endpoint, for example
"login.microsoftonline.com", the authority for Azure Public Cloud, which is the default
when no value is given.
Service principal with certificate:
- **AZURE_TENANT_ID**: ID of the service principal's tenant. Also called its 'directory' ID.
- **AZURE_CLIENT_ID**: the service principal's client ID
- **AZURE_CLIENT_CERTIFICATE_PATH**: path to a PEM or PKCS12 certificate file including the private key.
- **AZURE_CLIENT_CERTIFICATE_PASSWORD**: (optional) password of the certificate file, if any.
- **AZURE_AUTHORITY_HOST**: authority of a Microsoft Entra endpoint, for example
"login.microsoftonline.com", the authority for Azure Public Cloud, which is the default
when no value is given.
.. admonition:: Example:
.. literalinclude:: ../samples/credential_creation_code_snippets.py
:start-after: [START create_environment_credential_async]
:end-before: [END create_environment_credential_async]
:language: python
:dedent: 4
:caption: Create an EnvironmentCredential.
"""
def __init__(self, **kwargs: Any) -> None:
self._credential: Optional[Union[CertificateCredential, ClientSecretCredential]] = None
if all(os.environ.get(v) is not None for v in EnvironmentVariables.CLIENT_SECRET_VARS):
self._credential = ClientSecretCredential(
client_id=os.environ[EnvironmentVariables.AZURE_CLIENT_ID],
client_secret=os.environ[EnvironmentVariables.AZURE_CLIENT_SECRET],
tenant_id=os.environ[EnvironmentVariables.AZURE_TENANT_ID],
**kwargs
)
elif all(os.environ.get(v) is not None for v in EnvironmentVariables.CERT_VARS):
self._credential = CertificateCredential(
client_id=os.environ[EnvironmentVariables.AZURE_CLIENT_ID],
tenant_id=os.environ[EnvironmentVariables.AZURE_TENANT_ID],
certificate_path=os.environ[EnvironmentVariables.AZURE_CLIENT_CERTIFICATE_PATH],
password=os.environ.get(EnvironmentVariables.AZURE_CLIENT_CERTIFICATE_PASSWORD),
**kwargs
)
if self._credential:
_LOGGER.info("Environment is configured for %s", self._credential.__class__.__name__)
else:
expected_variables = set(EnvironmentVariables.CERT_VARS + EnvironmentVariables.CLIENT_SECRET_VARS)
set_variables = [v for v in expected_variables if v in os.environ]
if set_variables:
_LOGGER.log(
logging.INFO if kwargs.get("_within_dac") else logging.WARNING,
"Incomplete environment configuration for EnvironmentCredential. These variables are set: %s",
", ".join(set_variables),
)
else:
_LOGGER.info("No environment configuration found.")
async def __aenter__(self):
if self._credential:
await self._credential.__aenter__()
return self
async def close(self) -> None:
"""Close the credential's transport session."""
if self._credential:
await self._credential.__aexit__()
@log_get_token_async
async def get_token(
self, *scopes: str, claims: Optional[str] = None, tenant_id: Optional[str] = None, **kwargs: Any
) -> AccessToken:
"""Asynchronously request an access token for `scopes`.
This method is called automatically by Azure SDK clients.
:param str scopes: desired scopes for the access token. This method requires at least one scope.
For more information about scopes, see
https://learn.microsoft.com/azure/active-directory/develop/scopes-oidc.
:keyword str claims: additional claims required in the token, such as those returned in a resource provider's
claims challenge following an authorization failure.
:keyword str tenant_id: optional tenant to include in the token request.
:return: An access token with the desired scopes.
:rtype: ~azure.core.credentials.AccessToken
:raises ~azure.identity.CredentialUnavailableError: environment variable configuration is incomplete
"""
if not self._credential:
message = (
"EnvironmentCredential authentication unavailable. Environment variables are not fully configured.\n"
"Visit https://aka.ms/azsdk/python/identity/environmentcredential/troubleshoot to troubleshoot "
"this issue."
)
raise CredentialUnavailableError(message=message)
return await self._credential.get_token(*scopes, claims=claims, tenant_id=tenant_id, **kwargs)