[GitHub] [airflow] turbaszek commented on a change in pull request #9639: Add secrets backend for microsoft azure key vault

[GitBox <gi...@apache.org>]

turbaszek commented on a change in pull request #9639:
URL: https://github.com/apache/airflow/pull/9639#discussion_r449519179



##########
File path: airflow/providers/microsoft/azure/secrets/azure_key_vault.py
##########
@@ -0,0 +1,107 @@
+"""
+This module contains a secrets backend for Azure Key Vault.
+"""
+from typing import Optional
+
+from azure.identity import DefaultAzureCredential
+from azure.keyvault.secrets import SecretClient
+from azure.core.exceptions import ResourceNotFoundError
+from cached_property import cached_property
+
+from airflow.secrets import BaseSecretsBackend
+from airflow.utils.log.logging_mixin import LoggingMixin
+
+
+class AzureKeyVaultBackend(BaseSecretsBackend, LoggingMixin):
+    """
+    Retrieves Airflow Connections or Variables from Azure Key Vault secrets.
+
+    The Azure Key Vault can be configred as a secrets backend in the ``airflow.cfg``:
+
+    .. code-block:: ini
+
+        [secrets]
+        backend = airflow.providers.microsoft.azure.secrets.azure_key_vault.AzureKeyVaultBackend
+        backend_kwargs = {"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``.
+
+    :param vault_url: The URL of an Azure Key Vault to use
+    :type vault_url: str
+    :param connections_prefix: Specifies the prefix of the secret to read to get Connections
+    :type connections_prefix: str
+    :param variables_prefix: Specifies the prefix of the secret to read to get Variables
+    :type variables_prefix: str
+    :param sep: separator used to concatenate secret_prefix and secret_id. Default: "-"
+    :type sep: str
+    """
+
+    def __init__(self, vault_url: str = None, connections_prefix: str = 'airflow-connections',
+                 variables_prefix: str = 'airflow-variables', sep: str = '-', **kwargs):
+        super().__init__(**kwargs)
+        self.connections_prefix = connections_prefix.rstrip(sep)
+        self.variables_prefix = variables_prefix.rstrip(sep)
+        self.vault_url = vault_url
+        self.sep = sep
+        self.kwargs = kwargs
+
+    @cached_property
+    def client(self):
+        """
+        Create a Azure Key Vault client.
+        """
+        credential = DefaultAzureCredential()
+        client = SecretClient(
+            vault_url=self.vault_url,
+            credential=credential,
+            **self.kwargs
+        )
+        return client
+
+    def get_conn_uri(self, conn_id: str) -> Optional[str]:
+        """
+        Get an Airflow Connection URI from an Azure Key Vault secret
+
+        :param conn_id: The Airflow connection id to retrieve
+        :type conn_id: str
+        """
+        return self._get_secret(self.connections_prefix, conn_id)
+
+    def get_variable(self, key: str) -> Optional[str]:
+        """
+        Get an Airflow Variable from an Azure Key Vault secret.
+
+        :param key: Variable Key
+        :type key: str
+        :return: Variable Value
+        """
+        return self._get_secret(self.variables_prefix, key)
+
+    @staticmethod
+    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
+        environmentvariables, so ``connection_default`` becomes ``connection-default``.
+
+        :param path_prefix: The path prefix of the secret to retrieve
+        :type path_prefix: str
+        :param secret_id: Name of the secret
+        :type secret_id: str
+        :param sep: Separator used to concatenate path_prefix and secret_id
+        :type sep: str
+        """
+        path = '{}{}{}'.format(path_prefix, sep, secret_id)

Review comment:
       ```suggestion
           path = f'{path_prefix}{sep}{secret_id}'
   ```




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