misc: set a default authentication backend priority (#45808)

src/authentic2/authenticators.py

@@ -57,6 +57,7 @@ class BaseAuthenticator(object):
 class LoginPasswordAuthenticator(BaseAuthenticator):
     id = 'password'
     submit_name = 'login-password-submit'
+    priority = 0
 
     def enabled(self):
         return app_settings.A2_AUTH_PASSWORD_ENABLE

src/authentic2/utils/__init__.py

@@ -203,7 +203,7 @@ def get_backends(setting_name='IDP_BACKENDS'):
         else:
             backend.name = None
         if not hasattr(backend, 'priority'):
-            backend.priority = 0
+            backend.priority = 999  # backend with undefined priority go last
         if backend.id and backend.id in kwargs_settings:
             kwargs.update(kwargs_settings[backend.id])
         backend.__dict__.update(kwargs)

src/authentic2_auth_oidc/authenticators.py

@@ -26,7 +26,7 @@ from authentic2.authenticators import BaseAuthenticator
 
 class OIDCAuthenticator(BaseAuthenticator):
     id = 'oidc'
-
+    priority = 2
 
     def enabled(self):
         return app_settings.ENABLE and utils.has_providers()

src/authentic2_auth_saml/authenticators.py

@@ -27,6 +27,7 @@ from . import app_settings
 
 class SAMLAuthenticator(BaseAuthenticator):
     id = 'saml'
+    priority = 3
 
     def enabled(self):
         return app_settings.enable and list(get_idps())