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"""
This module contains Azure Key Vault Backend.
.. spelling:word-list::
Entra
"""
from __future__ import annotations
import logging
import os
from functools import cached_property
from azure.core.exceptions import ResourceNotFoundError
from azure.identity import ClientSecretCredential, DefaultAzureCredential
from azure.keyvault.secrets import SecretClient
from airflow.providers.microsoft.azure.utils import get_sync_default_azure_credential
from airflow.secrets import BaseSecretsBackend
from airflow.utils.log.logging_mixin import LoggingMixin
[docs]
class AzureKeyVaultBackend(BaseSecretsBackend, LoggingMixin):
"""
Retrieves Airflow Connections or Variables from Azure Key Vault secrets.
The Azure Key Vault can be configured as a secrets backend in the ``airflow.cfg``:
.. code-block:: ini
[secrets]
backend = airflow.providers.microsoft.azure.secrets.key_vault.AzureKeyVaultBackend
backend_kwargs = {"connections_prefix": "airflow-connections", "vault_url": "<azure_key_vault_uri>"}
For example, if the secrets prefix is ``airflow-connections-smtp-default``, this would be accessible
if you provide ``{"connections_prefix": "airflow-connections"}`` and request conn_id ``smtp-default``.
And if variables prefix is ``airflow-variables-hello``, this would be accessible
if you provide ``{"variables_prefix": "airflow-variables"}`` and request variable key ``hello``.
For client authentication, the ``DefaultAzureCredential`` from the Azure Python SDK is used as
credential provider, which supports service principal, managed identity and user credentials
For example, to specify a service principal with secret you can set the environment variables
``AZURE_TENANT_ID``, ``AZURE_CLIENT_ID`` and ``AZURE_CLIENT_SECRET``.
.. seealso::
For more details on client authentication refer to the ``DefaultAzureCredential`` Class reference:
https://docs.microsoft.com/en-us/python/api/azure-identity/azure.identity.defaultazurecredential?view=azure-python
:param connections_prefix: Specifies the prefix of the secret to read to get Connections
If set to None (null), requests for connections will not be sent to Azure Key Vault
:param variables_prefix: Specifies the prefix of the secret to read to get Variables
If set to None (null), requests for variables will not be sent to Azure Key Vault
:param config_prefix: Specifies the prefix of the secret to read to get Variables.
If set to None (null), requests for configurations will not be sent to Azure Key Vault
:param vault_url: The URL of an Azure Key Vault to use
:param sep: separator used to concatenate secret_prefix and secret_id. Default: "-"
:param tenant_id: The tenant id of an Azure Key Vault to use.
If not given, it falls back to ``DefaultAzureCredential``
:param client_id: The client id of an Azure Key Vault to use.
If not given, it falls back to ``DefaultAzureCredential``
:param managed_identity_client_id: The client ID of a user-assigned managed identity.
If provided with `workload_identity_tenant_id`, they'll pass to ``DefaultAzureCredential``.
:param workload_identity_tenant_id: ID of the application's Microsoft Entra tenant.
Also called its "directory" ID.
If provided with `managed_identity_client_id`, they'll pass to ``DefaultAzureCredential``.
"""
def __init__(
self,
connections_prefix: str = "airflow-connections",
variables_prefix: str = "airflow-variables",
config_prefix: str = "airflow-config",
vault_url: str = "",
sep: str = "-",
*,
tenant_id: str = "",
client_id: str = "",
client_secret: str = "",
managed_identity_client_id: str = "",
workload_identity_tenant_id: str = "",
**kwargs,
) -> None:
super().__init__()
[docs]
self.vault_url = vault_url
if connections_prefix is not None:
self.connections_prefix = connections_prefix.rstrip(sep)
else:
self.connections_prefix = connections_prefix
if variables_prefix is not None:
self.variables_prefix = variables_prefix.rstrip(sep)
else:
self.variables_prefix = variables_prefix
if config_prefix is not None:
self.config_prefix = config_prefix.rstrip(sep)
else:
self.config_prefix = config_prefix
logger = logging.getLogger("azure.core.pipeline.policies.http_logging_policy")
try:
logger.setLevel(os.environ.get("AZURE_HTTP_LOGGING_LEVEL", logging.WARNING))
except ValueError:
logger.setLevel(logging.WARNING)
[docs]
self.tenant_id = tenant_id
[docs]
self.client_id = client_id
[docs]
self.client_secret = client_secret
[docs]
self.managed_identity_client_id = managed_identity_client_id
[docs]
self.workload_identity_tenant_id = workload_identity_tenant_id
@cached_property
[docs]
def client(self) -> SecretClient:
"""Create a Azure Key Vault client."""
credential: ClientSecretCredential | DefaultAzureCredential
if all([self.tenant_id, self.client_id, self.client_secret]):
credential = ClientSecretCredential(self.tenant_id, self.client_id, self.client_secret)
else:
credential = get_sync_default_azure_credential(
managed_identity_client_id=self.managed_identity_client_id,
workload_identity_tenant_id=self.workload_identity_tenant_id,
)
client = SecretClient(vault_url=self.vault_url, credential=credential, **self.kwargs)
return client
[docs]
def get_conn_value(self, conn_id: str) -> str | None:
"""
Get a serialized representation of Airflow Connection from an Azure Key Vault secret.
:param conn_id: The Airflow connection id to retrieve
"""
if self.connections_prefix is None:
return None
return self._get_secret(self.connections_prefix, conn_id)
[docs]
def get_variable(self, key: str) -> str | None:
"""
Get an Airflow Variable from an Azure Key Vault secret.
:param key: Variable Key
:return: Variable Value
"""
if self.variables_prefix is None:
return None
return self._get_secret(self.variables_prefix, key)
[docs]
def get_config(self, key: str) -> str | None:
"""
Get Airflow Configuration.
:param key: Configuration Option Key
:return: Configuration Option Value
"""
if self.config_prefix is None:
return None
return self._get_secret(self.config_prefix, key)
@staticmethod
[docs]
def build_path(path_prefix: str, secret_id: str, sep: str = "-") -> str:
"""
Given a path_prefix and secret_id, build a valid secret name for the Azure Key Vault Backend.
Also replaces underscore in the path with dashes to support easy switching between
environment variables, so ``connection_default`` becomes ``connection-default``.
:param path_prefix: The path prefix of the secret to retrieve
:param secret_id: Name of the secret
:param sep: Separator used to concatenate path_prefix and secret_id
"""
# When an empty prefix is given, do not add a separator to the secret name
if path_prefix == "":
path = f"{secret_id}"
else:
path = f"{path_prefix}{sep}{secret_id}"
return path.replace("_", sep)
def _get_secret(self, path_prefix: str, secret_id: str) -> str | None:
"""
Get an Azure Key Vault secret value.
:param path_prefix: Prefix for the Path to get Secret
:param secret_id: Secret Key
"""
name = self.build_path(path_prefix, secret_id, self.sep)
try:
secret = self.client.get_secret(name=name)
return secret.value
except ResourceNotFoundError as ex:
self.log.debug("Secret %s not found: %s", name, ex)
return None