Autodetect path prefix for SSO endpoints

ai_web_common/flask_sso/ext.py

@@ -42,8 +42,14 @@ def init_sso(app, talisman):
             app.config['SSO_SERVICE'], app.config['SSO_DOMAIN'],
             app.config.get('SSO_GROUPS'))
 
-    app.add_url_rule('/sso_login', 'sso_login', _sso_login)
-    app.add_url_rule('/sso_logout', 'sso_logout',
+    # Install handlers for the SSO HTTP endpoints (sso_login and
+    # sso_logout). We assume that the app is served at the domain root
+    # (/), and attempt to derive the endpoints path prefix by looking
+    # at the SSO_SERVICE, in case we need to set up authentication on
+    # a subdirectory of the site only.
+    service_path = app.sso_service[app.sso_service.find('/'):]
+    app.add_url_rule(service_path + 'sso_login', 'sso_login', _sso_login)
+    app.add_url_rule(service_path + 'sso_logout', 'sso_logout',
                      talisman(frame_options=ALLOW_FROM,
                               frame_options_alow_from='*')(_sso_logout))