Support async Authorizers (#1373)

jupyter_server/auth/authorizer.py

@@ -9,7 +9,7 @@
 # Distributed under the terms of the Modified BSD License.
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Awaitable
 
 from traitlets import Instance
 from traitlets.config import LoggingConfigurable
@@ -44,7 +44,7 @@ class Authorizer(LoggingConfigurable):
 
     def is_authorized(
         self, handler: JupyterHandler, user: User, action: str, resource: str
-    ) -> bool:
+    ) -> Awaitable[bool] | bool:
         """A method to determine if ``user`` is authorized to perform ``action``
         (read, write, or execute) on the ``resource`` type.
 

jupyter_server/auth/decorator.py

@@ -2,9 +2,11 @@
 """
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
+import asyncio
 from functools import wraps
 from typing import Any, Callable, Optional, TypeVar, Union, cast
 
+from jupyter_core.utils import ensure_async
 from tornado.log import app_log
 from tornado.web import HTTPError
 
@@ -42,7 +44,7 @@ def authorized(
 
     def wrapper(method):
         @wraps(method)
-        def inner(self, *args, **kwargs):
+        async def inner(self, *args, **kwargs):
             # default values for action, resource
             nonlocal action
             nonlocal resource
@@ -61,8 +63,15 @@ def inner(self, *args, **kwargs):
                 raise HTTPError(status_code=403, log_message=message)
             # If the user is allowed to do this action,
             # call the method.
-            if self.authorizer.is_authorized(self, user, action, resource):
-                return method(self, *args, **kwargs)
+            authorized = await ensure_async(
+                self.authorizer.is_authorized(self, user, action, resource)
+            )
+            if authorized:
+                out = method(self, *args, **kwargs)
+                # If the method is a coroutine, await it
+                if asyncio.iscoroutine(out):
+                    return await out
+                return out
             # else raise an exception.
             else:
                 raise HTTPError(status_code=403, log_message=message)

tests/auth/test_authorizer.py

@@ -1,12 +1,18 @@
 """Tests for authorization"""
+import asyncio
 import json
 import os
+from typing import Awaitable
 
 import pytest
 from jupyter_client.kernelspec import NATIVE_KERNEL_NAME
 from nbformat import writes
 from nbformat.v4 import new_notebook
+from traitlets import Bool
 
+from jupyter_server.auth.authorizer import Authorizer
+from jupyter_server.auth.identity import User
+from jupyter_server.base.handlers import JupyterHandler
 from jupyter_server.services.security import csp_report_uri
 
 
@@ -217,3 +223,45 @@ async def test_authorized_requests(
 
     code = await send_request(url, body=body, method=method)
     assert code in expected_codes
+
+
+class AsyncAuthorizerTest(Authorizer):
+    """Test that an asynchronous authorizer would still work."""
+
+    called = Bool(False)
+
+    async def mock_async_fetch(self) -> True:
+        """Mock an async fetch"""
+        # Mock a hang for a half a second.
+        await asyncio.sleep(0.5)
+        return True
+
+    async def is_authorized(
+        self, handler: JupyterHandler, user: User, action: str, resource: str
+    ) -> Awaitable[bool]:
+        response = await self.mock_async_fetch()
+        self.called = True
+        return response
+
+
+@pytest.mark.parametrize(
+    "jp_server_config,",
+    [
+        {
+            "ServerApp": {"authorizer_class": AsyncAuthorizerTest},
+            "jpserver_extensions": {"jupyter_server_terminals": True},
+        }
+    ],
+)
+async def test_async_authorizer(
+    request,
+    io_loop,
+    send_request,
+    tmp_path,
+    jp_serverapp,
+):
+    code = await send_request("/api/status", method="GET")
+    assert code == 200
+    # Ensure that the authorizor method finished its request.
+    assert hasattr(jp_serverapp.authorizer, "called")
+    assert jp_serverapp.authorizer.called is True