Support arbitrary authenticators

- Removes all need for special casing authenticators.
- Install them in hub environment, directly start using them.
- Consider if we should special case any *at all*

tests/test_configurer.py

@@ -125,3 +125,21 @@ def test_auth_firstuse():
     })
     assert c.JupyterHub.authenticator_class == 'firstuseauthenticator.FirstUseAuthenticator'
     assert c.FirstUseAuthenticator.create_users
+
+
+def test_auth_github():
+    """
+    Test using GitHub authenticator, which is not explicitly special cased.
+    """
+    c = apply_mock_config({
+        'auth': {
+            'type': 'oauthenticator.github.GitHubOAuthenticator',
+            'GitHubOAuthenticator': {
+                'client_id': 'something',
+                'client_secret': 'something-else'
+            }
+        }
+    })
+    assert c.JupyterHub.authenticator_class == 'oauthenticator.github.GitHubOAuthenticator'
+    assert c.GitHubOAuthenticator.client_id == 'something'
+    assert c.GitHubOAuthenticator.client_secret == 'something-else'

tljh/configurer.py

@@ -70,13 +70,22 @@ def update_auth(c, config):
         'firstuse': 'firstuseauthenticator.FirstUseAuthenticator'
     }
 
-    authenticator_classname = authenticator_class_map[auth['type']]
-    c.JupyterHub.authenticator_class = authenticator_classname
+    if auth['type'] in authenticator_class_map:
+        authenticator_class = authenticator_class_map[auth['type']]
+        authenticator_configname = auth['type']
+    else:
+        # FIXME: Make sure this is something importable.
+        # FIXME: SECURITY: Class must inherit from Authenticator, to prevent us being
+        # used to set arbitrary properties on arbitrary types of objects!
+        authenticator_class = auth['type']
+        # When specifying fully qualified name, use classname as key for config
+        authenticator_configname = authenticator_class.split('.')[-1]
+    c.JupyterHub.authenticator_class = authenticator_class
     # Use just class name when setting config. If authenticator is dummyauthenticator.DummyAuthenticator,
     # its config will be set under c.DummyAuthenticator
-    authenticator_parent = getattr(c, authenticator_classname.split('.')[-1])
+    authenticator_parent = getattr(c, authenticator_class.split('.')[-1])
 
-    for k, v in auth[auth['type']].items():
+    for k, v in auth.get(authenticator_configname, {}).items():
         set_if_not_none(authenticator_parent, k, v)