[Identity] Align samples with other languages (Azure#20966)

sdk/identity/azure-identity/samples/README.md

@@ -34,6 +34,6 @@ pip install azure-identity azure-keyvault-certificates azure-keyvault-secrets
 | File | Description |
 |-------------|-------------|
 | control_interactive_prompts.py | demonstrates controlling when interactive credentials prompt for user interaction |
-| custom_credentials.py | demonstrates custom credential implementation |
+| custom_credentials.py | demonstrates custom credential implementations using existing access tokens and an MSAL client |
 | key_vault_cert.py | demonstrates authenticating with a Key Vault certificate |
-| user_authentication.py | demonstrates user authentication API for applications |
+| user_authentication.py | demonstrates user authentication and token cache persistence API for applications |

sdk/identity/azure-identity/samples/custom_credentials.py

@@ -2,11 +2,14 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
 # ------------------------------------
-"""Demonstrates custom credential implementation"""
+"""Demonstrates custom credential implementations using existing access tokens and an MSAL client"""
 
+import time
 from typing import TYPE_CHECKING
 
 from azure.core.credentials import AccessToken
+from azure.identity import AuthenticationRequiredError, AzureAuthorityHosts
+import msal
 
 if TYPE_CHECKING:
     from typing import Any, Union
@@ -32,3 +35,25 @@ def get_token(self, *scopes, **kwargs):
         """get_token is the only method a credential must implement"""
 
         return self._token
+
+
+class MsalTokenCredential(object):
+    """Uses an MSAL client directly to obtain access tokens with an interactive flow."""
+    def __init__(self, tenant_id, client_id):
+        # type: (str, str) -> None
+        self._app = msal.PublicClientApplication(
+            client_id=client_id, authority="https://{}/{}".format(AzureAuthorityHosts.AZURE_PUBLIC_CLOUD, tenant_id)
+        )
+
+    def get_token(self, *scopes, **kwargs):
+        # type: (*str, **Any) -> AccessToken
+        """get_token is the only method a credential must implement"""
+
+        now = int(time.time())
+        result = self._app.acquire_token_interactive(list(scopes), **kwargs)
+
+        try:
+            return AccessToken(result["access_token"], now + int(result["expires_in"]))
+        except:
+            print("\nFailed to get a valid access token")
+            raise AuthenticationRequiredError(scopes)

sdk/identity/azure-identity/samples/user_authentication.py

@@ -25,6 +25,7 @@
 # The 'authenticate' method begins interactive authentication. Call it whenever it's convenient
 # for your application to authenticate a user. It returns a record of the authentication.
 record = credential.authenticate()
+print("\nAuthenticated first credential")
 
 # The record contains no authentication secrets. You can serialize it to JSON for storage.
 record_json = record.serialize()
@@ -33,6 +34,7 @@
 # without prompting for authentication again.
 client = SecretClient(VAULT_URL, credential)
 secret_names = [s.name for s in client.list_properties_of_secrets()]
+print("\nCompleted request with first credential")
 
 # An authentication record stored by your application enables other credentials to access data from
 # past authentications. If the cache contains sufficient data, this eliminates the need for your
@@ -45,3 +47,14 @@
 # This request should also succeed without prompting for authentication.
 client = SecretClient(VAULT_URL, new_credential)
 secret_names = [s.name for s in client.list_properties_of_secrets()]
+print("\nCompleted request with credential using shared cache")
+
+# To isolate the token cache from other applications, you can provide a cache name to TokenCachePersistenceOptions.
+separate_cache_credential = InteractiveBrowserCredential(
+    cache_persistence_options=TokenCachePersistenceOptions(name="my_app"), authentication_record=deserialized_record
+)
+
+# This request should prompt for authentication since the credential is using a separate cache.
+client = SecretClient(VAULT_URL, separate_cache_credential)
+secret_names = [s.name for s in client.list_properties_of_secrets()]
+print("\nCompleted request with credential using separate cache")