allow handlers to work without an authorizer in the Tornado settings (#717)

Author: Zsailer

jupyter_server/auth/decorator.py

@@ -2,6 +2,7 @@
 """
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
+import warnings
 from functools import wraps
 from typing import Callable
 from typing import Optional
@@ -13,6 +14,20 @@
 from .utils import HTTP_METHOD_TO_AUTH_ACTION
 
 
+def raise_no_authorizer_warning():
+    warnings.warn(
+        "The Tornado web application does not have an 'authorizer' defined "
+        "in its settings. In future releases of jupyter_server, this will "
+        "be a required key for all subclasses of `JupyterHandler`. For an "
+        "example, see the jupyter_server source code for how to "
+        "add an authorizer to the tornado settings: "
+        "https://github.com/jupyter-server/jupyter_server/blob/"
+        "653740cbad7ce0c8a8752ce83e4d3c2c754b13cb/jupyter_server/serverapp.py"
+        "#L234-L256",
+        # stacklevel=2
+    )
+
+
 def authorized(
     action: Optional[Union[str, Callable]] = None,
     resource: Optional[str] = None,
@@ -61,7 +76,11 @@ 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):
+            if not self.authorizer:
+                with warnings.catch_warnings():
+                    warnings.simplefilter("once")
+                    raise_no_authorizer_warning()
+            elif self.authorizer.is_authorized(self, user, action, resource):
                 return method(self, *args, **kwargs)
             # else raise an exception.
             else:

jupyter_server/base/handlers.py

@@ -193,7 +193,7 @@ def login_available(self):
 
     @property
     def authorizer(self):
-        return self.settings["authorizer"]
+        return self.settings.get("authorizer")
 
 
 class JupyterHandler(AuthenticatedHandler):