web: Allow CASProvider config to be any source

By defining ``env`` in ``CASProvider``, the superclass implementation
of ``is_configured`` requires the variables to be set in the actual
environment.  Configuration can come from reading in ``/run/secrets``,
an ``.env`` file, or the environment.

This commit defines our own ``is_configured`` that checks ``CONFIG``
for the needed variables instead of relying on the superclass.

Additionally, add ``CHAINLIT_AUTH_SECRET`` to ``_NEEDS_ENVIRON``.

Ref: AP-412

Author: awilfox

willa/config/__init__.py

@@ -109,7 +109,8 @@
 
 
 _NEEDS_ENVIRON: list[str] = ['AWS_DEFAULT_REGION', 'AWS_ACCESS_KEY_ID', 'AWS_SECRET_ACCESS_KEY',
-                             'LANGFUSE_HOST', 'LANGFUSE_PUBLIC_KEY', 'LANGFUSE_SECRET_KEY']
+                             'LANGFUSE_HOST', 'LANGFUSE_PUBLIC_KEY', 'LANGFUSE_SECRET_KEY',
+                             'CHAINLIT_AUTH_SECRET']
 """A list of configuration keys that need to be set in the environment as well."""
 
 for key in _NEEDS_ENVIRON:

willa/web/cas_provider.py

@@ -66,6 +66,9 @@ def __init__(self) -> None:
             'scope': 'openid profile berkeley_edu_groups',
         }
 
+    def is_configured(self) -> bool:
+        return all(var in CONFIG for var in self.env)
+
     async def get_token(self, code: str, url: str) -> str:
         request = {
             'client_id': self.client_id,