I have implemented qa-external. It seems to work as far as SSO is concerned.
However, when posting a question, I get a foreign key-constraint violation as the external user does not exist inside qa_users:
[Mon May 25 11:40:04 2015] [error] [client 173.245.51.173] PHP Question2Answer MySQL query error 1452: Cannot add or update a child row: a foreign key constraint fails (`qanda`.`qa_posts`, CONSTRAINT `qa_posts_ibfk_1` FOREIGN KEY (`userid`) REFERENCES `qa_users` (`userid`) ON DELETE SET NULL) - Query: INSERT INTO qa_posts (categoryid, type, parentid, userid, cookieid, createip, title, content, format, tags, notify, name, created) VALUES (7, 'Q', NULL, '508815', NULL, INET_ATON('\\0\\0\\0\\0\\0\\0\\0\\0\\0\\0\\0\\0]\x85\xb8G'), 'This is a test....', Is this a test or not?', '', '', '@', NULL, NOW()),
The qa_users table is empty.qa_userlogins is also empty